Whats the quickest way to better bhp in a 318?
 

Well as it says really.... i am looking for advise on the best way to improve the bhp on my 318.

first a bit of history on what I have at the moment.... I have a 318 with an Edelbrock performer inlet and 4 barrel carb. its got a mild cam in it but i didn't put it in so its an unknown entity. I have, ready to go on, a 6 pack made for the 318/340...The car is running open header system with supertraps on the end at the moment.

My question is this... what is:

A) The cheapest way of improving BHP in a 318 eg what bits will get the best improvement... no guessing now, I need to know from experience please.

B) the best equipment...not necesserily the cheapest to do the same.

C) Would swapping the heads help?...if so who makes them? and which are best?

Depending on the year, but mostly, swapping 340/360 heads onto a 318 drastically lowers the compression ratio, unless you spend loads of money on special pistons.

You can screw around milling heads, which leads to intake fit problems.

Putting a six pack on a 318 would be a complete waste of time, there are far better single 4 manifolds that will give you better performance on that combo

The sad fact is, that the way to more performance is to yank the 318 and find a 360--because 340's are getting rare

360's of course have their own swap problems, the pan is different, you need to change the flywheel for balance.

This, unfortunately, is one of the big screw-ups, so far's I'm concerned, with Mopar SB's, something the Chivvy lovers don't have

You just need the surfaces of the intake milled as well. Any good machine shop should know what needs to be done to do it properly.

But I agree that a 360 is the best way to go to get power out of a SB. Just get a block and start from the ground up (thats what im doing right now). get the block machined, balanced. new pistons, heads, you should be able to use your performer intake on the 360, although the performer RPM would work better on it. etc. the 360 just has a lot more potential. thats why I got rid of my 318

Problem is, i love the 318 I have...its bullet proof and has never skipped a beat in all the time i have had it...ok now this is where all you Mopar guys will turn your backs on me...I have a 32 Ford with this 318 and 727 torqflight in it...the reason for the 6 pack is it looks more nostalgic than the 4 barrel I have on it already... It is going on the car whatever happens...$2000 later you can be sure i am putting it on.... i love the look of it....but I want to improve the performance, especially making up for the possible loss of performance the 6 pack may produce as you have stated.

now about these heads...I understand Edelbrock do a set of Ali heads for the 318....is it still best to fit 340 or 360 heads instead of the 318 ones??? and is it a straight forward bolt on job or will I need to get machining done?

IF you are going with that 6pack, you may want to look at getting HUGE valves both exhaust and intake. otherwise you will not be able to take advantage of the air you are pulling in. If you get too much air and it cannot exit the vehicle quick enough you will have a sluggish 0-30mph time. but you will have amazing times from 30-90 :D

get your heads port matched to your intake, and get the exhaust ports ported as well. Getting flat top pistons will help to raise the compression, but if you are tearing the motor down that far, you might as well go with a 360 like was mentioned before.

with a 318 the displacement just isnt there to have a 6pack like on the 440 motors.
the 360 motors can be just as dependable as the 318, they are identical blocks with the exception of the 360 having a bigger bore. And aside from different (bigger) valves, longer stroke, and an external balance, I believe they are identical.

The 6 pack i have bought was supplied by a well known Mopar supplier in the states and has been built for a 318/340 and has been jetted with that in mind...it also has a progressive linkage so too much air is not an issue...but time will tell I suppose... I think the best way forward is to get some heads from Edelbrock for a 360. That should take care of the larger valve issues you think i will have..... Port matching is a good idea and will be easier with ali heads and inlet....so thats the heads....

now what about the exhaust...as you can see by the picture I added earlier...they are cones...I wanted to change them to 4 pipes each side...kind of like zoomies but i think they need some kind of baffel in them...back pressure or lack of it may be a problem... any suggestions on that???

You can achieve bigger valves by simply bolting 360 heads onto your 318 block.

Yes but the compression will drastically fall. You'll have to mill the heads to get it back, and may have to mill the intake to fit--at which time you've just ruined the intake for any other use. That's an expensive decision, nowadays.

so would a middle of the road attitude apply here...If I fit 340 heads will it do the job or should I buy the ali heads from Edelbrock for the 318 which i believe has larger valves in them anyway.... i still want the car to be good on the street and if I buy these heads at over £1000 i dont really want to be skimming them... that would put the cost up which is the opposite of what i am trying to achieve.

I appreciate all your help guys...but the answer is getting a bit fuzzy.... so let me recap..

i have the triple carb set up which was made for the 318/340 and jetted accordingly... I am looking to get the coresponding heads from Edelbrock for the 318.

is there anything else that from your experience i can do to improve BHP without having to get something engineered...how about the cam??? is there a specific one that works well in this engine????...is there a stroker kit???...remember I have been a Ford man most of my life so Mopar is all a bit alien to me...i dont want to have to change this lump as it is a real work horse and it is giving me consistent mid 13s on the strip...i just want more..

Hmmmm, it's funny you say that. I just built a 68 model year 318 and put heads off of a later model year Cordoba 360. I added Keith Black 9.5:1 pistons; Edelbrock Performer RPM Cam & Lifter kit, Performer RPM Intake, and an 600cfm edelbrock carb and haven't suffered a bit of compression loss yet and I had nothing milled anymore than what it should have been for a normal rebuild. Engine went in my 73 Dart Sport and runs like a charm sittin in front of a doctored 904/2500 stall with 3.23 rearend.

if you want real performance make it a 391 strocker or you can go even bigger with the 318 LA motor. You can go to speed-o-motive.com they can do it and if you have any other ?s you can ask them as well, they have a long history with this motors

i went to the dyno recently. made 20 pulls.... this is what i got for me....

my stuff...

360/414 edelbrock rpm heads+level III porting. valve job etc..super victor intake speed demon 850dp
11.3:1 comp. runs perfect on pump gas. 3200stall.

1" 4 hole spacer= +4bhp (bhp=at wheels power)
1" open spacer= +7bhp
2" open spacer=not tested yet but installed
basic velocity stack cleaner with thin foam element. (like the edelbrock triangle one)
MINUS -47bhp!!!! wtf!? i thought they would flow best! 1000cfm+ my a**!

use only K+N larger the better. dyno guy told me filter tops actually hurt HP. sub stacks help. next trip ill be testing sub stacks bases etc...i have a 5" tall 9" round k+n im putting on. he said hes seen alot of filters and only k+n makes best pwr. best is no cleaner with base plate only. but thats not smart obviously.

timing! what are you running for timing? whats your cam duration? make sure you run enough advance atleast 14', im running 18' for my setup. 36 total. this dramatically effects carb signal. will completely change how much bhp your making. and most overlooked. 12/32 degrees is not the magic number.

edelbrock heads flow crappy. very turbulent and not consistent. they flow more than stock but i was surprised to see the numbers. the exhaust was even worse. basic porting got 25-35cfm more out of intake and 50-60 more cfm out of exhaust and made all ports matched. but as far as value its your best choice. i think they are 1250$? for the complete set? but i would get bare heads and manley valves then you can choose your springs etc for your cam or use what you got if they test ok.. edelbrock had some bad valves floating around, mine were some of them. manley race flo's are nice. you can find them on ebay, small block chevy vlaves work good in the edlebrock heads to correct geometry and lower cost. you can get the slightly shorter 4.911" vlaves to help correct the tip pattern without machinig the rocker stands.

in short. what to do now? air cleaner! sub-stack! timing! carb tuned! you get all that straight and that is easy cheap HP. then what accessories you running? if you got pwr steering that always help to go manual. everything affects bhp. how are your axles bearings etc? drain your rear-end lube and use royal purple. 30$ for 2 qts.

f.y.i. hot rod tv took a camaro. replaced engine oil, rear-end oil, and trans fluid with royal purple. thats it. nothing else. they got 12bhp. thats maybe 16-20hp at the flywheel? pretty good just for changing oil.

crane makes retrofit roller cam kit, pricy but thats always good power, roller rockers etc. this is all easy access stuff. yes 318 stroker kits available. check mancini racing. eagle h beams, diamond pistons, forged crank, bearings, all balanced for 1750! thats a good price...

be careful. port matching isnt always a good idea. due to scavenging. as long as intake is smaller than head i would leave it. and i bet you $ the air cleaner on that 6 pack is killing you. saw a reproduction type air cleaner on a shelby rob 100HP at the flywheel.

see if you can run a k+n or try it open and see the difference. and 273/318 were one style block 340/360 another. the mounts, 340 bore size is bigger than all. starts at 4.030 i think...318 starts 3.98"? right?... so 340 heads on 318? (or am i mis-reading...) might have valve clearance issues. maybe im not sure but i would check it out.

all i have is a great article about the 318 involves some machining but prices arent crazy
http://www.popularhotrodding.com/eng...ine/index.html

true that! finding a 340 without paying $$$$ for it is hard! just went through it, but swapping 318 to 360!? it ran me 118$. no problem at all and no pan clearance issues. im running a milodon 7 quart pan (thats pretty big) on my stroked 360, in my origional 318 b-body and everything works out just great. schumacker mounts made it a snap. no other mods, and balance? must be manual thing then... i got an automatic and there was no issue with balance. if your building a stroker wouldnt you internal balnce it anyways? i would....