TTOTM - Small blocks
06-10-2010, 06:50 AM
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Here's the info.... 
Chrysler's small-block V8 engines all derive from the classic A engine:
The 340
As the Detroit power wars heated up in the mid-1960s, Chrysler decided to produce a small block V8 specifically designed for high performance applications. The goal was to have a lightweight, high output engine equally suited for the drag strip or an oval track. The result of this decision was the 340 cu in V8. Chrysler's engineers increased the 318's cylinder bores to 4.04-inch (103 mm) while keeping the 318's 3.31-inch (84 mm) stroke. It fitted a forged steel crankshaft instead of the cast nodular iron unit used in the 318. A 4-barrel carburetor was mated to a high-rise, dual plane intake manifold. This induction setup fed into a set of cylinder heads that are still considered one of the best of that era. The heads were high-flow items with big ports, and used 2.02-inch (51 mm) intake and 1.60-inch (41 mm) exhaust valves. An aggressive cam was fitted to take advantage of the much better breathing top end. 1968 4-Speed cars got an even hotter cam, but it was discontinued in 1969. The engine was equipped with hydraulic lifters. Power output was officially stated as 275 hp (205 kW) for the 4 barrel and 290 hp (216 kW) for the 6-pack version with triple 2-barrel carburetors. Using flat-top pistons, the 340's compression ratio was 10.5:1, placing it near the limit of what was possible on pump gas. The 340 also used heavy-duty parts such as a dual timing chain, windage tray and revised oil pump.
In 1970, Chrysler offered a special version of the 340 for use in the Challenger TA and Cuda AAR. The "TA" engine featured a heavy duty short block featuring additional webbing in block to allow for 4 bolt main bearing caps, double roller timing chain and 10.5:1 compression. The heads featured larger ports compared to a standard 340 and offset rocker arms that allowed the pushrods to be moved away from the intake ports for improved airflow. They featured an aluminium intake manifold with three two barrel Holley carburetors and a dual points ignition system.
Like many other performance V8's of the day, for insurance reasons, the 340 engine's power output was officially understated. In reality, either the 4bbl or 6bbl configuration could produce at least 315 to 320 hp (235 to 239 kW). The 340 developed a reputation for outperforming much larger and heavier engines, with the attendant handling benefits provided by the relatively light-weight 340.
The 340 did not stay in production long. It was released in 1968, detuned with lower compression and smaller 1.88 inch intake valves in 1972, and was withdrawn from production after the 1973 model year.
The LA 360 (5.9 L) has a 4.00 in bore and a 3.58 in stroke. It was released in 1971 with a two barrel carburetor. The 360 used the large intake port 340 heads with a smaller intake valve (1.88 inch). In 1973, a 4-barrel version was released. In 1974, the 360 became the most powerful LA engine with the end of 340 production. After 1980, the 360 was primarily used in Dodge Ram trucks and vans. However, in some instances, the 360 was used in Dodge Diplomat police cars. The 1978-1979 Lil' Red Express truck used a special high performance 360 4-barrel engine, with factory production code EH1. The EH1 was a modified version of the E58 360 police engine (E58) producing 225 hp (168 kW) net @ 3800 rpm. Some prototypes for the EH1 featured Mopar Performance W2 heads, although the production units had the standard 360 heads. The 360 was replaced for 2003 with the 5.7 L Hemi.
The LA family was updated and branded as the Magnum V6 and V8 in 1992. While the Magnum 3.9, Magnum 5.2, and Magnum 5.9 (1993-up) engines were significantly based on the 239, the 318, and the 360 — respectively — many of the parts will not directly interchange and are not technically LA engines (the only parts that are actually unchanged are the crankshafts and connecting rods). Magnum cylinder heads use a different oiling system and individually mounted rocker arms (AMC style) and a CCW rotation water pump with a much improved housing. The intake manifolds share basic dimensions but will not interchange without modifications. Chrysler's engineers redesigned the oil seals on the crankshaft to improve anti-leak seal performance. Although the pre-Magnum ('71-'92) and Magnum versions of the 360/5.9 are both externally balanced, the two are balanced differently (the 360 Magnum uses lighter pistons) and each requires a uniquely balanced damper, flywheel, drive plate, or torque converter. The valve covers on the Magnum have 10 bolts rather than the previous 5, for improved oil sealing.
Chrysler offers a line of crate engines based on the Magnum designed to bolt into older muscle cars and street rods with little modification. Some of the changes to facilitate this were using a 1970-93 water pump so that older pulleys and brackets could be used, as well as an intake manifold that uses a carburetor instead of fuel injection. With a high lift cam and single plane intake, the crate Magnum 360 was rated at 380 hp (280 kW) with the Magnum heads. Later models equipped with "R/T" or aluminum cylinder heads produced 390 hp (290 kW). A 425-HP bolt-in fuel injection conversion kit is also available.
The Magnum 5.2, released in 1992, was an evolutionary development of the 318 with the same displacement. The Magnum development included the multiport fuel injection, new cylinder heads with a closed combustion chamber, a new higher-flow valve angle, increased valve lift, and new intake and exhaust manifolds. Power was up to 225 hp (168 kW) and 295 lb·ft (400 N·m). Production of the Magnum 5.2 ended with the 2003 model year Dodge Ram Van. It was replaced by the new 4.7 L PowerTech V8.
The Magnum 5.9 is an evolution of the 360. It got the Magnum V8 name with the same new manifolds, heads, and fuel injection as the 5.2 for 1993. Engine output that year was 230 hp (170 kW) and 325 lb·ft . The engine eventually produced 250 hp (190 kW) and 345 lb·ft on the version used in the Dakota RT. Starting in 2003, the 5.7 L Hemi V8 began replacing this engine.
Chrysler's small-block V8 engines all derive from the classic A engine:
- 1964½-1992 LA small-block - An evolution of the 1955 Plymouth A engine, using wedge-shaped instead of the prior polyspherical combustion chambers.
- 1992-2003 Magnum small-blockThe original LA design was almost totally revised for 1992 (318) and 1993 (360), with the only carry-over parts being the crankshaft and connecting rods. The only A/LA/Magnum-derived engine design currently in production is the Viper V10. (273/318/340/360)
- 5.7 L Hemi - The modern Hemi, introduced in 2002.
- 6.1 L Hemi - A larger modern Hemi, introduced in 2004. Sometimes called the 3G or Gen 3 Hemi to distinguish from earlier Hemi engines.
- The 273 (4.5 L) was the first LA engine, introduced in 1964 and offered through 1969, rated at 180 BHp. It had a 3.625 in (92 mm) bore and 3.31 in (84 mm) stroke. It had a mechanical solid lifter valvetrain until 1968 when hydraulic lifters were introduced. A special version was also available in 1966 only - it used a 0.500-inch (12.7 mm) lift solid-lifter camshaft, fabricated-steel-tube exhaust, and a Holley 4-barrel carburetor, producing 275 horsepower (1 hp/cu in). It was available in the Dodge Dart only, and the car so equipped was called the "D-Dart".
The 340
As the Detroit power wars heated up in the mid-1960s, Chrysler decided to produce a small block V8 specifically designed for high performance applications. The goal was to have a lightweight, high output engine equally suited for the drag strip or an oval track. The result of this decision was the 340 cu in V8. Chrysler's engineers increased the 318's cylinder bores to 4.04-inch (103 mm) while keeping the 318's 3.31-inch (84 mm) stroke. It fitted a forged steel crankshaft instead of the cast nodular iron unit used in the 318. A 4-barrel carburetor was mated to a high-rise, dual plane intake manifold. This induction setup fed into a set of cylinder heads that are still considered one of the best of that era. The heads were high-flow items with big ports, and used 2.02-inch (51 mm) intake and 1.60-inch (41 mm) exhaust valves. An aggressive cam was fitted to take advantage of the much better breathing top end. 1968 4-Speed cars got an even hotter cam, but it was discontinued in 1969. The engine was equipped with hydraulic lifters. Power output was officially stated as 275 hp (205 kW) for the 4 barrel and 290 hp (216 kW) for the 6-pack version with triple 2-barrel carburetors. Using flat-top pistons, the 340's compression ratio was 10.5:1, placing it near the limit of what was possible on pump gas. The 340 also used heavy-duty parts such as a dual timing chain, windage tray and revised oil pump.
In 1970, Chrysler offered a special version of the 340 for use in the Challenger TA and Cuda AAR. The "TA" engine featured a heavy duty short block featuring additional webbing in block to allow for 4 bolt main bearing caps, double roller timing chain and 10.5:1 compression. The heads featured larger ports compared to a standard 340 and offset rocker arms that allowed the pushrods to be moved away from the intake ports for improved airflow. They featured an aluminium intake manifold with three two barrel Holley carburetors and a dual points ignition system.
Like many other performance V8's of the day, for insurance reasons, the 340 engine's power output was officially understated. In reality, either the 4bbl or 6bbl configuration could produce at least 315 to 320 hp (235 to 239 kW). The 340 developed a reputation for outperforming much larger and heavier engines, with the attendant handling benefits provided by the relatively light-weight 340.
The 340 did not stay in production long. It was released in 1968, detuned with lower compression and smaller 1.88 inch intake valves in 1972, and was withdrawn from production after the 1973 model year.
The LA 360 (5.9 L) has a 4.00 in bore and a 3.58 in stroke. It was released in 1971 with a two barrel carburetor. The 360 used the large intake port 340 heads with a smaller intake valve (1.88 inch). In 1973, a 4-barrel version was released. In 1974, the 360 became the most powerful LA engine with the end of 340 production. After 1980, the 360 was primarily used in Dodge Ram trucks and vans. However, in some instances, the 360 was used in Dodge Diplomat police cars. The 1978-1979 Lil' Red Express truck used a special high performance 360 4-barrel engine, with factory production code EH1. The EH1 was a modified version of the E58 360 police engine (E58) producing 225 hp (168 kW) net @ 3800 rpm. Some prototypes for the EH1 featured Mopar Performance W2 heads, although the production units had the standard 360 heads. The 360 was replaced for 2003 with the 5.7 L Hemi.
The LA family was updated and branded as the Magnum V6 and V8 in 1992. While the Magnum 3.9, Magnum 5.2, and Magnum 5.9 (1993-up) engines were significantly based on the 239, the 318, and the 360 — respectively — many of the parts will not directly interchange and are not technically LA engines (the only parts that are actually unchanged are the crankshafts and connecting rods). Magnum cylinder heads use a different oiling system and individually mounted rocker arms (AMC style) and a CCW rotation water pump with a much improved housing. The intake manifolds share basic dimensions but will not interchange without modifications. Chrysler's engineers redesigned the oil seals on the crankshaft to improve anti-leak seal performance. Although the pre-Magnum ('71-'92) and Magnum versions of the 360/5.9 are both externally balanced, the two are balanced differently (the 360 Magnum uses lighter pistons) and each requires a uniquely balanced damper, flywheel, drive plate, or torque converter. The valve covers on the Magnum have 10 bolts rather than the previous 5, for improved oil sealing.
Chrysler offers a line of crate engines based on the Magnum designed to bolt into older muscle cars and street rods with little modification. Some of the changes to facilitate this were using a 1970-93 water pump so that older pulleys and brackets could be used, as well as an intake manifold that uses a carburetor instead of fuel injection. With a high lift cam and single plane intake, the crate Magnum 360 was rated at 380 hp (280 kW) with the Magnum heads. Later models equipped with "R/T" or aluminum cylinder heads produced 390 hp (290 kW). A 425-HP bolt-in fuel injection conversion kit is also available.
The Magnum 5.2, released in 1992, was an evolutionary development of the 318 with the same displacement. The Magnum development included the multiport fuel injection, new cylinder heads with a closed combustion chamber, a new higher-flow valve angle, increased valve lift, and new intake and exhaust manifolds. Power was up to 225 hp (168 kW) and 295 lb·ft (400 N·m). Production of the Magnum 5.2 ended with the 2003 model year Dodge Ram Van. It was replaced by the new 4.7 L PowerTech V8.
The Magnum 5.9 is an evolution of the 360. It got the Magnum V8 name with the same new manifolds, heads, and fuel injection as the 5.2 for 1993. Engine output that year was 230 hp (170 kW) and 325 lb·ft . The engine eventually produced 250 hp (190 kW) and 345 lb·ft on the version used in the Dakota RT. Starting in 2003, the 5.7 L Hemi V8 began replacing this engine.
10-01-2010, 04:27 AM
#2
Admin
TTOTM - Small blocks
New month so we have a new topic to talk about. Rebuilding and building up small block Mopars, Poly, LA, Magnum etc.. What works well together, what doesn't, where to get parts, etc..
10-01-2010, 04:27 AM
#3
Admin
this is a quoted guide for the 360 380 crate engine, as seen in engine masters mag, not everyone reads it im sure so ill post so ppl can follow and build a engine like this,
block is a factory 5.9 magnum truck block (360) 60cc production closed chamber heads with 1.920 intake, and 1.88 exhaust. 1.6 ratio rockers, (standard magnum) single plane M-1 intake.
rollor hyd, camshaft 288/292 deg, gross (advertised) duration. .501-/.513 lift. pistions are 9.0:1.
on the dyno 750 mighty demond carb, 1-5/8 hooker headers thru 3 inc flowmaster mufflers, base line was set at 34 deg total advance. first pull it hit 377 hp @ 5100 tq was 375,
with a jet change of no.78 primary and no.87 secondary.
the final dyno pull showed
439.5 ft lb of TQ @ 4100 rpm
409 hp @5400 rpm
sorry if its a sloppy "write-up" but maybe this a can be helpfull in you next non stroked small block build.
if i seemed to miss any info you may need or want to know about. ask. i cannot garantee any outcome, its simply straight from a mag,
the engine used in this test was a mopar 360/380hp crate engine
block is a factory 5.9 magnum truck block (360) 60cc production closed chamber heads with 1.920 intake, and 1.88 exhaust. 1.6 ratio rockers, (standard magnum) single plane M-1 intake.
rollor hyd, camshaft 288/292 deg, gross (advertised) duration. .501-/.513 lift. pistions are 9.0:1.
on the dyno 750 mighty demond carb, 1-5/8 hooker headers thru 3 inc flowmaster mufflers, base line was set at 34 deg total advance. first pull it hit 377 hp @ 5100 tq was 375,
with a jet change of no.78 primary and no.87 secondary.
the final dyno pull showed
439.5 ft lb of TQ @ 4100 rpm
409 hp @5400 rpm
sorry if its a sloppy "write-up" but maybe this a can be helpfull in you next non stroked small block build.
if i seemed to miss any info you may need or want to know about. ask. i cannot garantee any outcome, its simply straight from a mag,
the engine used in this test was a mopar 360/380hp crate engine
10-04-2010, 10:16 PM
#4
Mopar Lover
Here is the combination I have for my 340
73 340 block
mild head work, I think. I've never had my motor apart, so I don't know what the heads look like.
MP 284/484 cam
about 9:1 Comp ratio IIRC
Edelbrock LD340 intake manifold
Holley 3310-2 carb tuned for the LD340 intake and cam
I honestly don't know much more about my 340. IIRC it has was I was told by a trusted friend is a good double roller timing chain.
Electronic ignition. I've used both the orange box and the chrome box.
IN my Duster with a 4.88:1 chuck, and 26" tires she ran 8.800-8.804 consistently.
73 340 block
mild head work, I think. I've never had my motor apart, so I don't know what the heads look like.
MP 284/484 cam
about 9:1 Comp ratio IIRC
Edelbrock LD340 intake manifold
Holley 3310-2 carb tuned for the LD340 intake and cam
I honestly don't know much more about my 340. IIRC it has was I was told by a trusted friend is a good double roller timing chain.
Electronic ignition. I've used both the orange box and the chrome box.
IN my Duster with a 4.88:1 chuck, and 26" tires she ran 8.800-8.804 consistently.
10-04-2010, 11:05 PM
#5
Mopar Lover
318 for my Demon Sizzler
My 318 for the Demon Sizzler will be as follows:
I'm hoping for a bout 3-350 rear wheel horse power.
Wadaya think?
j
- 71 or 72 318 Block
- Not sure on the heads. Thinking of aluminum tho
- Edelbock performer RPM intake or MP M1 Dual plane
- Windage Tray
- High volume oil pump
- forged or KB pistons
- 9.8:1 Comp. ratio
- MP cam
- P4452761 Camshaft, 0.450"/0.455" Lift, 268/272 Adv. Duration
- P4452992 Camshaft, 0.474"/0.474" Lift, 280/280 Adv. Duration
- Holley, or carter 750 carb
- Eletronic Ignition
- Headers to 2.5" exhaust dumping at the rear axle
I'm hoping for a bout 3-350 rear wheel horse power.
Wadaya think?
j
10-04-2010, 11:28 PM
#6
Mopar Lover
One thing I would like to find out is what are the good/better/best small block heads are available, stock iron to aluminum.
Over at one of my HT forums, we came up with some budget builds with multiple budgets in mind. I'd like to see something like that here. We could pick three different budget targets and pick out combinations that fit. We could also put together combinations based on 1/4 times, HP figures desired, or what have you.
What say you?
j
Over at one of my HT forums, we came up with some budget builds with multiple budgets in mind. I'd like to see something like that here. We could pick three different budget targets and pick out combinations that fit. We could also put together combinations based on 1/4 times, HP figures desired, or what have you.
What say you?
j
10-05-2010, 02:32 AM
#7
Admin
There are different cast iron heads out there for the small blocks and They are lettered. I know one is an "X" and another is "J" I think (might be wrong). I'm sure that someone will pipe up and say what they are.
A set of alum heads on a small block really help to wake up these motors, especially if a little port and polishing is done.
MReeves should be chiming in soon since he has built a few for racing. I'm sure that he would have some good opions on how to build a strong track motor.
A set of alum heads on a small block really help to wake up these motors, especially if a little port and polishing is done.
MReeves should be chiming in soon since he has built a few for racing. I'm sure that he would have some good opions on how to build a strong track motor.
10-05-2010, 10:01 AM
#8
Mopar Lover
Another question I have is concerning the Magnum motors. I have heard talk of using Magnum heads on LA motors. Is that possible? If so, what does it take? If not, what heads have the heart shaped combustion chambers? Do we need a specific TTOM for heads? Might not be a bad idea 
j
j
10-05-2010, 10:05 AM
#9
Admin
I have heard from some that the magnum heads will work on an LA motor.... others say they will not. I have read that the water passages are different but have not been able to confirm any of it.
As far as building a small block (or big block) on a budget, that is a thread that I can start in the General discussion area.
As far as building a small block (or big block) on a budget, that is a thread that I can start in the General discussion area.
10-11-2010, 10:16 PM
#10
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what motor to get and where?
im new to anything mopar. Got a killer deal on a custom 35 plymouth 5 window. Has a 727 tranny in. I dont want a huge motor or anything crazy... just a good motor that will sounds good go good and can be an everyday driver! It had a 360 and i dont know if i should go that rout or what? Any advice or ideas would be much appreciated! thanks guys!
10-12-2010, 12:27 AM
#11
Mopar Lover
I've got most of my motors from Craigslist. I picked up a 400/727 combo, a 360/727 combo, a 440, and a fairly complete 318. all for about $500. Now, granted, they all need rebuilt, so figure those are core prices. You can probably find exactly what you are looking for there.
Good luck, and post some pix of that Plymouth!
j
Good luck, and post some pix of that Plymouth!
j
10-12-2010, 03:24 AM
#12
Admin
im new to anything mopar. Got a killer deal on a custom 35 plymouth 5 window. Has a 727 tranny in. I dont want a huge motor or anything crazy... just a good motor that will sounds good go good and can be an everyday driver! It had a 360 and i dont know if i should go that rout or what? Any advice or ideas would be much appreciated! thanks guys!
10-26-2010, 12:42 AM
#13
Mopar Lover
How much power?
Thinking of this recipe for my Demon:
With a good converter, and say 3.23 or 3.55 gears, I am expecting a punchy, fun ride. What kind of power do you think I can get out of the above combination? What suggestions do y'all have?
j
- 318 Block
- 9.8:1 Comp. Ratio Forged Pistions
- MP P5153849 Aluminum heads
- MP M1 Dual Plane, or Edelbrock Performer/RPM Intake Manifold
- Edelbrock Performer series carb
- K&N Air cleaner
- MP Electonic Ignition
- Hooker Comp 1 5/8" Primary, 3" collector headers 2.5" exhaust
With a good converter, and say 3.23 or 3.55 gears, I am expecting a punchy, fun ride. What kind of power do you think I can get out of the above combination? What suggestions do y'all have?
j
04-18-2011, 05:58 AM
#14
Admin
I've got some questions......
1) I know that the small block 318 LA motors are internally balanced and that the small block 360 LA motors are externally balanced (I think I may have just answered my own question but.....). Can you install a 360 crank into a 318 to get more stroke and still have it be interanlly balanced, would it then need to be externally balanced or can it just not be done?
2) I may be purchasing a truck with a 318 that has some performance goodies on/in it. Can the cam be removed and installed into a 360 (I don't see why not but thought I'd ask)? If so, does it still need to be broken in or can it just be run?
3) I have yet to look and I really should before asking this next question but...... What benifit would a stroker 360 give me over a stock stroke 360 if they both have the same cam, intake, heads, headers, etc.?
2) I may be purchasing a truck with a 318 that has some performance goodies on/in it. Can the cam be removed and installed into a 360 (I don't see why not but thought I'd ask)? If so, does it still need to be broken in or can it just be run?
3) I have yet to look and I really should before asking this next question but...... What benifit would a stroker 360 give me over a stock stroke 360 if they both have the same cam, intake, heads, headers, etc.?
04-18-2011, 06:16 AM
#15
Admin
In my early stages of "mopar small block stroker kit" search, I found this link and believe that it will be a huge help to many of us building a SB LA motor.
http://www.dustyengineering.com/engine/stroker.html
http://www.dustyengineering.com/engine/stroker.html
04-18-2011, 10:12 PM
#16
360 & 318 maim bearings are a different size. I wouldn't use a cast crank..
I broke the one in my 360. I should have known better. It had a hi Vol oil pump and it sucked the stock pan dry one time at the track (lifters were rattling) The oil pressure was never the same I would bet the loose bearings allowed the crank to flex too much The magnum motor oils the head up thru the push rods. Part of the swap includes making some external oil lines for the head other wise your guess is as good as mine One of the mags did it years ago...
I broke the one in my 360. I should have known better. It had a hi Vol oil pump and it sucked the stock pan dry one time at the track (lifters were rattling) The oil pressure was never the same I would bet the loose bearings allowed the crank to flex too much The magnum motor oils the head up thru the push rods. Part of the swap includes making some external oil lines for the head other wise your guess is as good as mine One of the mags did it years ago...
04-19-2011, 05:25 AM
#17
Admin
I completely forgot all about the difference in materials of both cranks.
Why would I want to stroke a SB 360LA motor though?
Why would I want to stroke a SB 360LA motor though?
- I have heard with the longer "throw" (stroke) it allows the motor to make more torque easier. Is this true?
- I read that just stroking a motor is worthless and that you don't truely start seeing gains until you install other performance parts (cam, intake, heads, etc.). Is this true?
09-25-2011, 09:00 PM
#18
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Probably discussed a million times, but what budget headers are good for a mildly updated 72 cuda with a 318. I will flange match, and bowl port with a performance grind. Cam will be about a 0.44" lift, not sure yet on duration. RPM air gap with a holley double feed 650 as well.
thanks.
thanks.
12-14-2011, 09:15 PM
#19
Super Moderator
From an article at Mopar Muscle
One man's trash is another's treasure, and when it comes to bottom feeding in the world of Mopar engines the 318 seems like the biggest bargain in town. Know for efficient grocery getting in modest transportation, the musclecar aura never kissed the 318. Though the 318's long production run began in 1968, poised perfectly to participate in the height of the musclecar era, it was only available as a two-barrel economy until the deep dark days of the smog era in 1978. Without the cool reputation as a powerhouse like the bigger 340, 318s are routinely plucked from all manner of Chrysler products, and are practically handed out for haulage in Mopar circles. Be that as it may, there are some true 318 devotees in the Mopar world, impressed by the efficiency and long service this loyal mill provides.
So what's wrong with the 318? Obviously, it's a little light on displacement, but not compared to some more highly revered engines of the past-302 Chevys or Boss Fords, for instance. The most commonly heard objection is that the bore is small, creating shrouding that hurts flow and makes big power impossible, since at 3.91-inches it's not quite at the "magic" 4.000-inch mark. Yeah right-tell it to the LS1 crowd. Those engines are known for their breathing despite an even smaller bore. With Mopar's factory 18 degree valve angle, this is pretty much a moot point for most street builds. The fact is a 318 can be the basis for a nice small-displacement, high-rpm powerplant. With its short 3.31-inch stroke, high rpm are natural. A case can be made for a small-displacement street engine that's fuel efficient by virtue of its modest size, but piles on the power on demand when needed, by winding the revs up the scale. With the 318 Mopar as a base, such an engine can be built for a ridiculously low price. Better still, you will always be the underdog, and there is nothing like talking smack when putting the hurt on the big boys with a "lowly" 318.
Our goal was to build a hot street engine, using the attributes of the factory package to its best advantage, keeping the build as cheap as practical. All 318s use long 6.123-inch rods, though the 1973 and later engines had the stronger but heavier 340/360 forgings, which are better. These later rods are stout from the factory, and toy with engine speeds on the order of 6,500 rpm, and even a little more. Nearly all 318s came with cast cranks, and here again the factory stuff can take 6,500 rpm handily. In fact there is nothing in the stock engine that can't work exceptionally well in that rpm range, including the lubrication system, electronic ignition, and even the production valvetrain. I guess you can fairly say that these engines are all 6,500-plus-rpm screamers just waiting to be unleashed; here's how we did it.
The Build
Low compression is a drawback of any 318, with all of the factory pistons dwelling deep in the hole at TDC. The low-cost remedy here is a set of KB 167 flat-top pistons, which allow for a zero deck with minimal milling. We had the guys at Precision Speed and Machine, in Bakersfield, California, punch our virgin 318 block 0.040-inch over, to 3.950-inch (getting close to 4.000-inch there, aren't we?), and then zero deck the block. With this overbore, the 318 grows to 324 cid. This minimal level of machining prep will usually be all that is required to build a hot street 318. We used a 273 steel crank in our engine, only because we found it in the dirt at the local boneyard, but any of the factory cast cranks are more than up to the job. To complete the short-block, we had the rods reconditioned with new Pioneer bolts, and used a factory windage tray, as well as a homemade sheetmetal baffle in the pan to prevent oil slosh. A summery of bottom-end mods is a pretty short list, basically all we did was put the flat top pistons in, milled for zero deck, balanced it, and put it back together with all re-conned factory stock stuff. Moving on to the top-end, here is where you might expect to find the secrets to making the big power put down by this little engine. Well, normally a really trick set of heads can work wonders, but here we just used a boneyard set of plain old 360 Mopar smog heads. After all, few guys will cap a $500 short with a $1,500 set of heads. All of those '70s-80s 360 heads essentially carry the same port layout of the high performance 340, and as far as run-of-the-mill production iron of the era, they are about as good as it gets. In fact, these old-school heads have a big advantage over the later castings. The pushrod constriction is much less intrusive than that found on engines spawned in the hydraulic roller era, far less than even the Magnum heads of the '90s. The bottom line is that these 360 heads have plenty of intake port for a very stout 318.
Low compression is a drawback of any 318, with all of the factory pistons dwelling deep in the hole at TDC. The low-cost remedy here is a set of KB 167 flat-top pistons, which allow for a zero deck with minimal milling. We had the guys at Precision Speed and Machine, in Bakersfield, California, punch our virgin 318 block 0.040-inch over, to 3.950-inch (getting close to 4.000-inch there, aren't we?), and then zero deck the block. With this overbore, the 318 grows to 324 cid. This minimal level of machining prep will usually be all that is required to build a hot street 318. We used a 273 steel crank in our engine, only because we found it in the dirt at the local boneyard, but any of the factory cast cranks are more than up to the job. To complete the short-block, we had the rods reconditioned with new Pioneer bolts, and used a factory windage tray, as well as a homemade sheetmetal baffle in the pan to prevent oil slosh. A summery of bottom-end mods is a pretty short list, basically all we did was put the flat top pistons in, milled for zero deck, balanced it, and put it back together with all re-conned factory stock stuff. Moving on to the top-end, here is where you might expect to find the secrets to making the big power put down by this little engine. Well, normally a really trick set of heads can work wonders, but here we just used a boneyard set of plain old 360 Mopar smog heads. After all, few guys will cap a $500 short with a $1,500 set of heads. All of those '70s-80s 360 heads essentially carry the same port layout of the high performance 340, and as far as run-of-the-mill production iron of the era, they are about as good as it gets. In fact, these old-school heads have a big advantage over the later castings. The pushrod constriction is much less intrusive than that found on engines spawned in the hydraulic roller era, far less than even the Magnum heads of the '90s. The bottom line is that these 360 heads have plenty of intake port for a very stout 318.
All of the 360 Mopar heads came from the factory with 1.88-inch intake valves, 1.600-inch valves at the exhaust, and big open chambers, at 72cc. To step things up, we started by having the heads machined for 2.02-inch intake valves. Some weird urban legend has it that 2.02-inch intake valves will not fit a 318, or that bore notches are required. Actually, even a standard-bore 318 will swallow valves of this size, so no problemo for our 0.040-over mill. After the seat machining, the heads received a little porting, consisting of a basic bowl blend, and some work at the pushrod area. Far from an all-out effort, these heads got little more than a swizzle of the carbide cutter-not even the ugly guide bosses were cut. These modifications may not seem like much, but it was enough to tap well into the potential of the castings, and produce respectable flow (See: Flow Chart). To reduce the chamber volume for our small displacement engine, the heads were milled fairly heavily to 60cc.
Even though most guys think 318s don't have what it takes to make power, we started with a production 318 block, and decided to build it on the cheap. Precision Speed and Machine (PSM) punched it 0.040 for a set of KB 167 flat-tops, and zero decked it. We gave it the customary clean before assembly.
Federal Mogul bearings were used throughout the build. We used Childs & Albert assembly lube to coat the plain bearing at the rods and crank.
Though most 318s came with cast cranks, we happened to run across a factory-forged crank from a 273. Don't feel bad if all you have is a cast iron piece, they are generally reliable at 6,500 rpm. We balanced the crank at PSM, and recommend you do, too. The odd-looking bolts at the No. 2 and 4 main caps are to take the factory windage tray. We used the stock main fasteners.
Even though we went with the cheaper Federal Mogul moly pre-gapped rebuilder's rings instead of the better file-fit SpeedPros, we checked the gaps to get them in specs for the KB pistons, which run wider gaps.
The KB 167 pistons have deep valve notches that will swallow all kinds of lift, even with milled heads. The pistons have to go in order corresponding to the valve layout.
The rods are regular Mopar factory units, actually the 73-up 318 forgings, which are the same as the 360 rods, which were the same as the 340 high-performance rods, except without the pin bushings. These rods are long at 6.123", and you won't break them with your street 318 (or 360). The rods were reconditioned, fitted with new Pioneer bolts, and the pistons hung, at PSM. We just put them in their holes and torqued-up.
12-14-2011, 09:16 PM
#20
Super Moderator
Part 2
Tallying up so far we had a stock short with flat-tops, and a set of milled junkyard heads with bigger intake valves and very modest porting. It may not sound like much, but this is good stuff for a 318 build. The next consideration was the camshaft. Here we gravitated towards a hydraulic flat tappet, which may not be romantic, but is certainly budget conscious. A solid flat tappet certainly would have offered even more rpm potential, but a hydraulic allows us to use the factory valvetrain. While the OEM valvetrain is non-adjustable, and looks as low-tech as it gets, it is extraordinarily lightweight, and being a shaft system, it's as stable as it comes. With a hydraulic cam, the ugly stock stuff will out-rpm virtually anything from the aftermarket.So what's wrong with the 318? Obviously, it's a little light on displacement, but not compared to some more highly revered engines of the past-302 Chevys or Boss Fords, for instance. The most commonly heard objection is that the bore is small, creating shrouding that hurts flow and makes big power impossible, since at 3.91-inches it's not quite at the "magic" 4.000-inch mark. Yeah right-tell it to the LS1 crowd. Those engines are known for their breathing despite an even smaller bore. With Mopar's factory 18 degree valve angle, this is pretty much a moot point for most street builds. The fact is a 318 can be the basis for a nice small-displacement, high-rpm powerplant. With its short 3.31-inch stroke, high rpm are natural. A case can be made for a small-displacement street engine that's fuel efficient by virtue of its modest size, but piles on the power on demand when needed, by winding the revs up the scale. With the 318 Mopar as a base, such an engine can be built for a ridiculously low price. Better still, you will always be the underdog, and there is nothing like talking smack when putting the hurt on the big boys with a "lowly" 318.
Our goal was to build a hot street engine, using the attributes of the factory package to its best advantage, keeping the build as cheap as practical. All 318s use long 6.123-inch rods, though the 1973 and later engines had the stronger but heavier 340/360 forgings, which are better. These later rods are stout from the factory, and toy with engine speeds on the order of 6,500 rpm, and even a little more. Nearly all 318s came with cast cranks, and here again the factory stuff can take 6,500 rpm handily. In fact there is nothing in the stock engine that can't work exceptionally well in that rpm range, including the lubrication system, electronic ignition, and even the production valvetrain. I guess you can fairly say that these engines are all 6,500-plus-rpm screamers just waiting to be unleashed; here's how we did it.
Mopars have another advantage, and that is the 0.904-inch tappet diameter, which translates to about 8 percent more intensity at the valve with a cam designed to make use of the large lifter diameter. COMP has just the cams for the job, with their Mopar-only XEHL series. This is a variation of the popular Xtreme Energy cam series, but built to provide the additional intensity the 0.904-inch lifters allow. We went with the smallest of this series, the XE275HL, specing out at 231/237-degrees duration at 0.050, and 0.525-inch lift, on a 110 degree lobe separation angle. This duration level is enough to give a noticeable chop at idle, but not temperamental enough to make you insane in day-to-day driving. To cope with the aggressive rate of this cam, we used a fairly significant level of spring load for a flat tappet, deciding on a set of COMP 972 single springs installed at 1.750-inch, for 140 lbs on the seat and 310 lbs over the nose.
The final aspect of the build to consider is the induction, and here past experience has taught us that there is no beating an Edelbrock Performer RPM AirGap in the street range up to 6,500 rpm. That much was a given, but motivated by ultimate cheapness we bolted-on a TransDapt adapter plate, which allowed us to mount a factory Mopar ThermoQuad carb. The TQ carb is actually a fine unit, and the one we used is the larger version rated at 850 cfm of airflow, though an 800-cfm unit was also OEM equipment. That may seem like a huge amount of carb for a 318, but an odd characteristic of the TQ is that it allows monstrous capacity to work on seemingly impossibly small combinations. Finally a set of TTI headers with 1 5/8- to 1 3/4-inch primaries were obtained to handle the exhaust, and we had our combo. On paper, it seemed pretty tame, a flat-top piston 318, with mildly reworked iron 360 smog heads, a hydraulic flat tappet, an Edelbrock two plane, a stock four barrel, and headers. We knew better.
Running The Numbers
When we brought our 318 to Westech Performance Group for testing, the attractively detailed 318 Mopar drew some interest, and naturally a few questions about the combination. We revealed it was a 318, basically a factory short-block put together with KB flat-tops and a hydraulic flat tappet, mildly ported ordinary factory 360 heads, and the four-barrel setup with the ThermoQuad visible to all. By the specs, it didn't seem like much, especially being "only a 318", so there was some serious doubt when we confidently stated that it should make over 400 hp. After all, mildly reworked 318s don't make that kind of power, especially with some junkyard heads. Well, it didn't take long to silence the skeptics, when the engine was broken in and then loaded against the brake for the first power pulls. With out baseline combination, the engine zinged-up the rpm scale to make 400 hp at 6,200-6,300 rpm.
When we brought our 318 to Westech Performance Group for testing, the attractively detailed 318 Mopar drew some interest, and naturally a few questions about the combination. We revealed it was a 318, basically a factory short-block put together with KB flat-tops and a hydraulic flat tappet, mildly ported ordinary factory 360 heads, and the four-barrel setup with the ThermoQuad visible to all. By the specs, it didn't seem like much, especially being "only a 318", so there was some serious doubt when we confidently stated that it should make over 400 hp. After all, mildly reworked 318s don't make that kind of power, especially with some junkyard heads. Well, it didn't take long to silence the skeptics, when the engine was broken in and then loaded against the brake for the first power pulls. With out baseline combination, the engine zinged-up the rpm scale to make 400 hp at 6,200-6,300 rpm.
We could see that the 318 was doing exactly what we expected-making lots of power and rpm. We could also see from the dyno sheets that the factory ThermoQuad carburetor was running at least a point too rich, and it was time to make a decision. There were a few things we wanted to try while on the dyno, and we only had one day reserved for testing, and about half of that was already eaten just setting the Mopar mill up on the dyno, and getting our baseline figures. Experience has taught us that playing with the ThermoQuad could easily soak the rest of the day in tuning, so we decided to substitute a Mighty Demon 750-cfm carb, primarily for its easy tuning changes. A 1-inch open spacer was used to mimic the 1-inch adapter that had been necessary with the ThermoQuad. With some quick jet changes of the Demon to get our mixture in the bullseye, we had 406 hp showing at the same 6,200-6,300 rpm peak.
We used a set of mildly worked factory 360 Smog heads. 2.02" intake valves were fitted, plus a nice performance valve job was done, along with some minor bowl blending. The heads were milled pretty heavily to reduce the chamber volume to 60cc. We built them with COMP's No. 972 spring installed at 1.750", giving 140 lbs on the seat and 310 over the nose.
A set of FelPro gaskets sealed the heads, which were installed using the stock 318 head bolts. The head/piston combination gave us a compression ratio of just over 10:1.
COMP's XE275HL is a hydraulic flat tappet designed for maximum intensity with a Mopar's 0.904" tappet diameter. Measuring 275/287 gross duration, 231-237 @ 0.050" tappet rise, and 0.525/0.525" lift with 1.5:1 rockers, this cam has very high lift for its duration, which means the best trade in all out power for a given idle quality.
12-14-2011, 09:20 PM
#21
Super Moderator
Part 3
Small-block Mopars use a thrust plate at the front of the cam, which restrains fore and aft motion. The tab under the right lower bolt was used in later engines for timing chain oiling, while earlier engines had four bolts retaining the thrust plate, with the upper right being hollow to allow oil to drain through it from the lifter valley.
Up front we re-used the stock timing case cover and damper, but purchased a generic new water pump for good measure. On these engines, install the damper before tightening the cover bolts, so that the damper's nose will center the front seal when the cover's fasteners are tightened down.
Underneath, everything is stock stuff, including the oil pump, pick-up, and windage tray. The tray was found on many heavy-duty, four barrel, or police 318s.
Inside, the engine still had its fill of 20-50 conventional diesel oil used for break-in. We figured the little Mopar mill had gotten over the critical flat tappet cam break-in period by now. There was the potential for a little more power with the oil change, so we switched to Lucas 5-20 full synthetic oil for our next series of runs. The synthetic offers a lower viscosity, and presumably lower friction, which we hoped would result in some additional power by a reduction of parasitic drag. The oil change proved to be a positive step, with output now reaching 412 hp at the exact same power peak.
Dyno operator Steve Brule suggested we might gain some additional power by swapping the 1-inch open spacer for a tapered combination spacer. We grabbed a 4150-sized HVH SuperSucker spacer from our shelf, and made the change. The SuperSucker provides a tapered entry from the carb into the plenum; with some combinations this can add incrementally to the output. It proved to be the case with our 318 Mopar combination, taking peak output to 415 hp at 6,300 rpm, which would prove to be the best numbers of the day.
Our 318 cam delivered a rated 0.525-inch lift with 1.5:1-ratio rockers. Under the valve covers we were running the stock Mopar hydraulic rocker valvetrain, which we just cleaned and re-used, including the stock solid bar 5/16-inch pushrods. Although this non-adjustable valvetrain looks crude, test after test has proven it to be remarkably capable in hydraulic cam applications where adustablility is not strictly required. These stamped-steel rockers are lighter than anything from the aftermarket, and the ingenious shaft-mount system lets the rockers ride with virtually no clearance on broad bearing surface at the lower half of the rocker, sliding on a film of oil much like a main bearing. Friction at the shaft is virtually nil, and the stability is excellent. Still, we wanted to see if a little more lift could be added with a higher rocker ratio, so we swapped to a set of aluminum 1.6:1 roller rockers. This would get us to 0.560-inch lift.
The rocker change didn't work out, and in fact, the engine's effective rpm range dropped dramatically, down to 6,100 rpm, as compared to the easy and clean 6,700 rpm ceiling (the limit of our test range, not the engine's rpm capabilities) with the factory stock 1.5:1 rockers. We tried setting the lash to zero, to curb lifter pump-up, but it didn't help. What went wrong? In my experience, there are definite limits to how much intensity can be used with a hydraulic lifter, be it a flat tappet or roller. We were over that line with our overall combination.
With the super-quick 0.904-inch cam lobe profile, even with the 1.5:1 rockers we were already reaching a very high lift when considering the overall duration. As previously noted, these "0.904-profile" lobes are about 8 percent faster than high intensity 0.842-profile lobes, and the high-ratio rockers add another 7 percent. At the resultant 0.560-inch lift on a 231 @ 0.050 lobe, with only 275 rated seat duration, the valve action is well into the range of a very aggressive solid roller, far faster, in fact, through the early stages of the valve event. The result is valvetrain instability, which the hydraulic mechanism of the lifter cannot cope with. We've been through it before, and increased spring load will do little to help the situation. Besides, with longevity in mind, our COMP No. 972 springs were at the limit of loads we'd run in a street flat tappet application. If hunting for the far reaches of hydraulic cam intensity and rpm, the direction has to be mass reduction throughout the valvetrain, including lightweight valves. The 3/8-stem street valves and now heavier rockers just weren't gong to cut it with this combination.
Should we be disappointed that the higher ratio rockers didn't work? Maybe not, since it told us that the factory stuff, when combined with the fast COMP lobe profiles, is in the upper range of the potential available. While more would definitely be possible with trick lightweight components like valves, these items are somewhat out of the budget nature of this build. It also reinforces the value of the stock Mopar valvetrain. It represents a significant cost savings compared to other makes of engines where a valvetrain swap is virtually mandatory for survival with a high performance cam. Thinking about the results, we were pretty happy with the 415 streetable hp and 6,500-plus rpm capabilities we got from Chrysler's neglected 318, especially considering how much of this engine consists of nothing more than mundane factory production parts.
It won't make you a lick of power on the dyno, but the best thing you can do to your small-block Mopar's lubrication system for the street is to add a pan baffle. We made this one, and welded it to the stock pan. If you don't want to fab, buy a baffled pan, or you will rash the bearings on slicks.
Meet Mr. Ugly; this ThermoQuad flows 850 cfm, and with enough patience and tuning will run with anything on a combo like this. Pluses include metering that is extremely sophisticated, a plastic body that keep fuel much cooler inside, and you can get them at an average of twenty bucks a throw. Minuses include laborious tuning. We used an 850-cfm TQ, on top of the excellent Edelbrock Performer RPM AirGap.
For hassle-free dyno duty, we stabbed an MSD distributor, which works with the Dyno's MSD box, along with MSD wires and Denso plugs to complete the ignition. A blue and a silver spring and the thick black bushing dialed in the timing curve for max power.
For exhaust, we went with TTI's excellent small-block Mopar step headers, and went the full exhaust route with a pair of Hooker Max-Flow mufflers. The mufflers didn't cost any horsepower.
Right off the bat our mongrel 318 clicked off 400 hp at 6,200-6,300 rpm, despite the TQ running too rich. Not bad, huh?
There is no debate that a Demon carb is easier and quicker to tune than the TQ, and time was ticking. We made a quick swap to a 750 Mighty Demon atop a Wilson spacer, and within a couple of jet changes had 406 hp at 6,200- 6,300 rpm.
An oil change to Lucas 5-20 synthetic, and a swap to a HVH tapered combo spacer helped power even more, allowing this "lowly" 318 to tag 415 hp. That's not a bad number for a simple and dirt cheap street combination, and more than we've seen some bigger street builds make.
Hollywood Steve "Stevie" Brule added a set of 1.6:1 aluminum rockers, and even set at zero lash, the rpm capability crashed. We had as much spring as we were willing to run on the street, so this is a dead player with the high-velocity cam, at least without serious attention to lightening the valvetrain. Some 8mm or hollow-stem valves, Ti. retainers, and beehive springs may have allowed the hydraulic lifters to cope.
03-19-2012, 05:17 PM
#24
The Mopar small block crate motors are left overs from the magnum runs at least in the current 360 version.
Two versions. I have worked on both.
The 300hp version was the truck 360 with the stock truck cam, a dual plane intake and a mopar distributor. Thats it! The short block is identical to production trucks.
The 380hp version is the same shortblock but with a cam that ups the lift to just under the retainer to guide contact limit. .. .501 ish.. (do the research on numbers, Im not positive on lift but they can take .520. They switched from dual intake to a single plane intake.
Same heads on both.
Both were underrated.
The stock 250hp truck motors were detuned and dont look to attractive under all the fuel injection and wiring. They ran fat fuel curves to save the cat converters and had ridiculously restrictive exhaust and an intake that peaked HP numbers at 4400rpm. This design hurts my head....Thus low HP numbers..
If you want low budget motor you can beat the snot out of grab a boneyard magnum 360 motor, carb, intake and dizzy. Leave the cam, its a torquey SOB for your 4000lb car)Take the converter with your boneyard motor to keep the external balance square, reuse your tranny. Keep the serpentine belt setup and add a little holley fuel E pump.
Later in life, add RHS, EDDY, or EQ heads to push flow past 250cfm and add some duration and 425HP with decent vacuum is super easy bolt on... Same short block.
Save money for some tires
Two versions. I have worked on both.
The 300hp version was the truck 360 with the stock truck cam, a dual plane intake and a mopar distributor. Thats it! The short block is identical to production trucks.
The 380hp version is the same shortblock but with a cam that ups the lift to just under the retainer to guide contact limit. .. .501 ish.. (do the research on numbers, Im not positive on lift but they can take .520. They switched from dual intake to a single plane intake.
Same heads on both.
Both were underrated.
The stock 250hp truck motors were detuned and dont look to attractive under all the fuel injection and wiring. They ran fat fuel curves to save the cat converters and had ridiculously restrictive exhaust and an intake that peaked HP numbers at 4400rpm. This design hurts my head....Thus low HP numbers..
If you want low budget motor you can beat the snot out of grab a boneyard magnum 360 motor, carb, intake and dizzy. Leave the cam, its a torquey SOB for your 4000lb car)Take the converter with your boneyard motor to keep the external balance square, reuse your tranny. Keep the serpentine belt setup and add a little holley fuel E pump.
Later in life, add RHS, EDDY, or EQ heads to push flow past 250cfm and add some duration and 425HP with decent vacuum is super easy bolt on... Same short block.
Save money for some tires
06-19-2012, 05:29 PM
#25
Mopar Lover
my 318 was a replacement crate motor with 2000 appx miles on it old ,mans 5th i bought the car pulled the engine and replaced it with a running 318 souped up around 80k on it 2yrs later we swapped it for the new............
the crate motor was a lean burn roller motor we pulled it apart checked for any major damage "none found " we replaced the bearings piston rings seals we honed the cylinders im not sure what the compresion ratio is and lifter bores installed a comp cams kit dual duration k 20-418-3 275 283 duration 462 482 lift the kit is awsome and a set of 360 heads i ported them but left the smaller valves in them giving me power pack heads, Mallory electronic distributor and coil "high voltage" air gap manifold 650 avs edelbrock mopar performance headers dual exhaust w turbo mufflers then dumps 727 trany with atg shift reprogramming kit 2.72 rear gear its amazing at the throttle response with that cam and the tall rear gear you cant mash it to the floor but with some feather footing it off the line she makes a good torky launch and when shes moving say 20 mph roll she is very competitive right up to 6000 rpm all for $1800 mustang camaro and zipper cars are surprised and humiliated when granpas old 5th ave beats or keeps up with there big sports cars they shift 3 times to my 1 5 speeds eh
MOPAR eats fords craps camaros and picks it teeth with toyotas. i hope that dosent get me in trouble? sorry...
This is my daily driver and the engine is very streetable, about 15 17 mpg city 16 19 mpg highway she is jst broken in and im very happy with her, nice sound very beefy deep sound.
all the parts where purchased from summit racing. 318s very durable motors
the crate motor was a lean burn roller motor we pulled it apart checked for any major damage "none found " we replaced the bearings piston rings seals we honed the cylinders im not sure what the compresion ratio is and lifter bores installed a comp cams kit dual duration k 20-418-3 275 283 duration 462 482 lift the kit is awsome and a set of 360 heads i ported them but left the smaller valves in them giving me power pack heads, Mallory electronic distributor and coil "high voltage" air gap manifold 650 avs edelbrock mopar performance headers dual exhaust w turbo mufflers then dumps 727 trany with atg shift reprogramming kit 2.72 rear gear its amazing at the throttle response with that cam and the tall rear gear you cant mash it to the floor but with some feather footing it off the line she makes a good torky launch and when shes moving say 20 mph roll she is very competitive right up to 6000 rpm all for $1800 mustang camaro and zipper cars are surprised and humiliated when granpas old 5th ave beats or keeps up with there big sports cars they shift 3 times to my 1 5 speeds eh
MOPAR eats fords craps camaros and picks it teeth with toyotas. i hope that dosent get me in trouble? sorry...
This is my daily driver and the engine is very streetable, about 15 17 mpg city 16 19 mpg highway she is jst broken in and im very happy with her, nice sound very beefy deep sound.
all the parts where purchased from summit racing. 318s very durable motors
06-20-2012, 02:37 AM
#26
Admin
The Mopar small block crate motors are left overs from the magnum runs at least in the current 360 version.
Two versions. I have worked on both.
The 300hp version was the truck 360 with the stock truck cam, a dual plane intake and a mopar distributor. Thats it! The short block is identical to production trucks.
The 380hp version is the same shortblock but with a cam that ups the lift to just under the retainer to guide contact limit. .. .501 ish.. (do the research on numbers, Im not positive on lift but they can take .520. They switched from dual intake to a single plane intake.
Same heads on both.
Both were underrated.
The stock 250hp truck motors were detuned and dont look to attractive under all the fuel injection and wiring. They ran fat fuel curves to save the cat converters and had ridiculously restrictive exhaust and an intake that peaked HP numbers at 4400rpm. This design hurts my head....Thus low HP numbers..
If you want low budget motor you can beat the snot out of grab a boneyard magnum 360 motor, carb, intake and dizzy. Leave the cam, its a torquey SOB for your 4000lb car)Take the converter with your boneyard motor to keep the external balance square, reuse your tranny. Keep the serpentine belt setup and add a little holley fuel E pump.
Later in life, add RHS, EDDY, or EQ heads to push flow past 250cfm and add some duration and 425HP with decent vacuum is super easy bolt on... Same short block.
Save money for some tires
Two versions. I have worked on both.
The 300hp version was the truck 360 with the stock truck cam, a dual plane intake and a mopar distributor. Thats it! The short block is identical to production trucks.
The 380hp version is the same shortblock but with a cam that ups the lift to just under the retainer to guide contact limit. .. .501 ish.. (do the research on numbers, Im not positive on lift but they can take .520. They switched from dual intake to a single plane intake.
Same heads on both.
Both were underrated.
The stock 250hp truck motors were detuned and dont look to attractive under all the fuel injection and wiring. They ran fat fuel curves to save the cat converters and had ridiculously restrictive exhaust and an intake that peaked HP numbers at 4400rpm. This design hurts my head....Thus low HP numbers..
If you want low budget motor you can beat the snot out of grab a boneyard magnum 360 motor, carb, intake and dizzy. Leave the cam, its a torquey SOB for your 4000lb car)Take the converter with your boneyard motor to keep the external balance square, reuse your tranny. Keep the serpentine belt setup and add a little holley fuel E pump.
Later in life, add RHS, EDDY, or EQ heads to push flow past 250cfm and add some duration and 425HP with decent vacuum is super easy bolt on... Same short block.
Save money for some tires
09-29-2012, 08:38 AM
#27
Probably discussed a million times, but what budget headers are good for a mildly updated 72 cuda with a 318. I will flange match, and bowl port with a performance grind. Cam will be about a 0.44" lift, not sure yet on duration. RPM air gap with a holley double feed 650 as well.
thanks.
thanks.
the only 3 headers for small blocks that do not have the steering going through them are the TTI [best ] Dougs [next best] & the Hooker 5115 , these are the onlyheaders I would consider using .
09-29-2012, 08:43 AM
#28
Another question I have is concerning the Magnum motors. I have heard talk of using Magnum heads on LA motors. Is that possible? If so, what does it take? If not, what heads have the heart shaped combustion chambers? Do we need a specific TTOM for heads? Might not be a bad idea
j
j
09-29-2012, 08:50 AM
#29
1) I know that the small block 318 LA motors are internally balanced and that the small block 360 LA motors are externally balanced (I think I may have just answered my own question but.....). Can you install a 360 crank into a 318 to get more stroke and still have it be interanlly balanced, would it then need to be externally balanced or can it just not be done?
2) I may be purchasing a truck with a 318 that has some performance goodies on/in it. Can the cam be removed and installed into a 360 (I don't see why not but thought I'd ask)? If so, does it still need to be broken in or can it just be run?
3) I have yet to look and I really should before asking this next question but...... What benifit would a stroker 360 give me over a stock stroke 360 if they both have the same cam, intake, heads, headers, etc.?
2) I may be purchasing a truck with a 318 that has some performance goodies on/in it. Can the cam be removed and installed into a 360 (I don't see why not but thought I'd ask)? If so, does it still need to be broken in or can it just be run?
3) I have yet to look and I really should before asking this next question but...... What benifit would a stroker 360 give me over a stock stroke 360 if they both have the same cam, intake, heads, headers, etc.?
2] cam can be used in a new build, if the engine has been run in you do not need to do a second break in
3]increasing the stroke increases displacement & power / torque
09-29-2012, 08:53 AM
#30
My 318 for the Demon Sizzler will be as follows:
I'm hoping for a bout 3-350 rear wheel horse power.
Wadaya think?
j
- 71 or 72 318 Block
- Not sure on the heads. Thinking of aluminum tho
- Edelbock performer RPM intake or MP M1 Dual plane
- Windage Tray
- High volume oil pump
- forged or KB pistons
- 9.8:1 Comp. ratio
- MP cam
- P4452761 Camshaft, 0.450"/0.455" Lift, 268/272 Adv. Duration
- P4452992 Camshaft, 0.474"/0.474" Lift, 280/280 Adv. Duration
- Holley, or carter 750 carb
- Eletronic Ignition
- Headers to 2.5" exhaust dumping at the rear axle
I'm hoping for a bout 3-350 rear wheel horse power.
Wadaya think?
j
