big block or small block
 

I Have a 70 plymouth belvedere with a 318 904 and 8 1/4. with manual drums all around. I know i need to at least put power front disc brakes.

I am having a hard time decide if i want a big block or a small block. im looking to get between 400 to 500 hp and torque. also want sure grip i have ac that works that i want to keep . does it go in the same spot as a sb or bb the ac?

What are the pros and cons of small block or a big block.
If i go with a 340 or 360 can i use the 904 and 8 1/4 and beef them up or am i going to need a 727 and a 8 3/4

if i go with a 440 what will i need to do. I know that i have to get bb motor mounts a bb radiator and radiator mount but what else.

do i just have to buy heave duty shocks and leaf springs. will i have to
get an engine stiffinging kit like subframe connectors etc.

Thanks for your input

440 needs at least an 8 3/4
its torque is too high for the others

If you want that horsepower, the 440 would be your best bet. Yup, go with the 727 and 8 3/4 rear. The A/C can use your compressor with the appropriate big block a/c brackets and pulleys. Youll have to get new a/c lines made. Might have to do a little "hunting" to find the 440. 400 big blocks easier to find. 383,s easy too. The front springs on your '70 are "torsion bar springs." They are fairly easy to replace and stiffer ones are readily available. Youll have to shorten the driveshaft to go from the 904-8 1/4 combo to the 727-8 3/4 setup.

For brakes, try Master Power Brakes. They use original style parts in their kits and are very complete. Rear drums should be fine.
Dont really need the subframe connector til about 470 HP.
Your current radiator mount can be modified for the larger rad.
I'd use some decent gas charged shocks; [eg: Koni].
Other than the few modifications, its pretty much a drop in deal.

i think you should get a stroker kit for a 318 or a 360. i would like to see someone do this build up and would like know how it comes out. ive seen kits where you can bore and stroke a 318 up to 391 cubic inches. it would be one hell of a sleeper if you could show somebody that little 318 and then actually have the power and torque of 391 that would be really kick **s

I'd go 440, Cheaper & more durable, you can get 500 hp from a small block, but it's going to be a Big cam, high compression & high RPM sort of deal, not the greatest for a heavy B-body....... 440 man .

well can somebody do a build up of a stroked small block then? :(

hypermite what is that sexy piece of machinery in your photo? i dont think ive ever seen one before.

If you want a hot rod do the 440, if you want a nice driver with a little power that gets decent gas milage and no hassles, do a 360 . theyres alot of them out there, in junk yards for cheap. and you can get 400 horses out of 1 with a few mods. yes youll need to get a 727 and an 8 3/4 rear for the car, if you dont mind 10 miles to the gallon big blocks the way to go.

you can use a 904 behind a 340/360 but its not recommended because you'll most likely blow it up unless you get a high dollar transmission kit for it. you would want a 727.

however i KNOW you would have much more fun with an A833 4 speed.
since you're swapping the engine out anyway, get a 360 or 340 thats set up for a manual.

why you should'nt get a big block: a big block will add about 150 lbs at least in the engine alone. then you will have to worry about the necessary suspension setup mods - springs a-arms, whatnot that will have to be beefier in order to support the heavier engine. that also adds a significant amount of weight and not to mention all the work needed to get the big block to fit in there. and when you do get it in there, if you want to run power steering AND headers, you will need to buy a very expensive set of headers designed to fit in a B body that has power steering. (the clearances get very tight with a big block) The OTHER reason, is the way your car will handle. all that added weight is gonna make your car understeer, and it wont handle nearly as well as you would with a small block. plus all that added weight - especially in the front - will be much harder on your brakes and you will take a LOT longer to stop unless you put some good money into brake upgrades.

why a 360 is perfect for your car: you said your other choice would be a 340 or 360. well a 340 is a nice high-revving engine, but it makes most of its power in high rpm's and not too much down low. and a B body is a fairly large car. while the 360 might have been considered a "low performance" engine of its day, i highly disagree. the early 360's 1971-1974 had many of the same parts as a 340. they had the same heads (915 and 587 castings) , valve sizes, (1972-73 340's 1.88/160 valves) same exact forged rods, and the natural advantages of a mopar small block: 18 degree cylinder head valve angle, and shaft mounted rockers. and the real cool thing, is that early 360's could take as big of an overbore as a 340 could. (since the 340 has a stock 4.040 bore, and the 360's bore is 4.000) so its possible to bore a 360 out .080, and maybe .100 (if it passes sonic checking)

the only "non-performance" aspect to the 360 is the cast crank. but then again theres plenty of Ch**y 350's running around out there with cast cranks. the nice thing about the 360 is also the larger main bearing journals - 2.81 as opposed to the smaller 273/318/340 2.50in journals. and if you get lucky - '74 and '75 360's had a shot peened cast crank - which would be a little stronger.

and a 360 will make enough low-end torque to keep your car happy and making it easier to roll out the clutch. it shouldnt cost too much to have the intake valves machined for 2.02in if you like, and a mildly built 360 can can handle spinning 6000 rpm. which is pretty good for a motor designed with low end torque in mind. and if they can make a budget 318 with 400 hp, then you can easily have a 360 making 400+ hp

Putting a big block in a B Body is a piece of cake. The OP isn't trying to shoe horn a 440 into a 64 Barracuda :confused: B Bodies were meant for big inch muscle. How many GTXs and Road Runners out there have small blocks? I don't know, and don't really care, cause the 440 +6 is where it's at.

IMHO, go with a 400 block, stroker kit from 440source.com, their Stealth aluminum heads, a nice TF automatic trans, a well built 8.75" rear, and have a blast with it. The stroker won't weigh quite what a 440 will, and you can make just as much power, if not more with the stroker.

If gas mileage is your concern, buy a Prius :p:p

j

Another option is a crate motor. I heard a rumour that they are 25% off right now. 392 crate hemi, fuel injected....525 Hp....mmmm:D

Find yourself a BB drivetrain out of a recked car and use it all. 440, 426, 383 with a 727 built up some and an 8 3/4 or dana 60 rear. I would be a lot easier than trying to build a small block motor to get those numbers that you want.

lol damnit i just love small blocks.

maybe i wasnt thinking clearly. i do know that you can build a nice 408 stroker outta a 360 with a 4inch stroker crank...

but then again, i really like 383's, since like most big blocks they can actually rev...

fine whatever. get a damn big block. just swap out the auto tranny for a 4spd...

so pretty much either way im going to have to go with e 727 and 8 3/4. im not going to do everything right now but i found a 440 engines on cragslisr a of a '77 440 out of a New Yorker. CAST crank a .484 MP Purple Shaft cam in it..sitting for 4 years I would recommend a rebuild though Has stock 452 hardened seat heads on it as well as a "187" C body oil pan (great for A body BB conversions as the pan is notched to allow pitman arm clearance) Has cheapo chrome VC's on it.
DOES NOT COME WITH INTAKE, DISTRIBUTOR, STOCK VC's $600

does that seem decent for a motor.how bad will my handling be with a 440.

there's the question you gotta answer yourself. Power and torque or handling.

How about this for a compromise; lightest bigblock setup I can think of;
400 lowdeck big block with a stroker kit (little bit lighter),edelbrock heads (aluminum), Edelbrock performer RPM intake (aluminum), quality set of headers (lighter than iron manifolds) change your A/C compressor to a Sanden compressor(waaay lighter than original compressor) use an Optima battery (lighter) high torque mini starter (lighter), use a mopar performance aluminum water pump housing (lighter) and maybe one of those import, smaller alternators (lighter), maybe even an aluminum radiator with electric fan. Factory aluminum master cylinder.

And you wouldn't have to change this all at once. You could do the changes one at a time.

when you say that i need bigblock motor mounts. how do you install them are they a bolt on or do u have to weld them into place? Another thing about handling i saw on GEARS stacey davids doing donuts in a 70 superbird with a 440 and said that the car was made for handling. I Know the superbird is a little different then mine but cant i improve handling with sway bars, engine stiffinng kit etc

Just use motor mounts for a '70 belvedere with a bigblock.
Motor mounts are a bolt on and you use your original "K" frame.
The 440 uses the same K frame as the 318 on your car so your good to go. No welding is required.
Yes, your car is basically like a superbird {obviously without the nose, tail and special backglass etc.} Swaybars would be a good choice for better handling.

It's my 78 Chrysler Cordoba, 400,727, I had N20 on it for a while, it ran low 13s @ 104 mph. This summer it's getting a 10.5 to 1 440 with Edelbrock heads & dual quads !

if i was thinking of putting a hemi in there is it basically the same as putting a big block with changing the motor mounts or is it alot more complicated than that.