Edelbrock heads on a 318?

[Hillbilly]

I'm going to be rebuilding a 318 and wondered if anyone knows about puting the Edelbrock heads on it. The Edelbrock tech line could only tell me they'll give 30-50 more HP over stock heads, but I'm worried that the ports and valves may be too big thus hurting flow velocity. I plan on running a higher compression piston (9.2+) and a Hughes cam with .228/.232 @.050 and .524/.540 lift reving up to 6000RPMs. I don't mind spending money on the heads, but if I'd be better off with a set of fully ported and polished 302 castings, I'd hate to waste the extra cash on the Edelbrocks. I don't think 320-330HP should be much problem, but my goal is 350HP. Please advise.....


I AM
HILLBILLY

[FASTDARTCHESTER]

Howdy,

Last year my Dart with a 318 went 12.90 with ported/polished '302 heads and 1.88/1.60 valves. 12.16@112 on a 100 hp shot of nitrous and significant tire spin. I know it woulda broke into the 11's but our time was up at the track.

TD

[eric414]

WHY?

[threefortyduste]

dont forget that aluminum heads not only add teh power, but they take significant wieght off the front end, which helps transfer weight to the rear...i say get em...
but 9.2 isnt exactly what i would call high compression...that was stock compression in 67-69 (unsure of the end year, but i know 67 and 68), you might want to jump to 10.25 or 10.5

[CW25]

Shoot for 10.5 with the aluminum heads IMO.

[RogerH]

The heads should work great, I'd match it with a 340/360 port exit intake manifold as well, as the 318 has smaller port exits.

I agree, that if you haven't bought pistons yet, I'd shoot for closer to 10:1 CR if you go with aluminum heads.

[Hillbilly]

I know that you can run higher compression with aluminum heads, but will premium pump gas be OK for 10.5:1 compression? Also, since the 318 is cubically challenged, how much should I worry about port velocity with these heads? I plan on mostly street driving with trips to the drags when I feel like it. Sorry for so many questions, I just wanted smoe tech advise before I start this venture.


I AM
HILLBILLY

[84ram]

10.5:1 would be the most compression that I would attempt to run with 93 octane pump gas, but if you have a good quench (say~.035"-.040") you should be OK at that level because the engine will not require as much ignition advance to make optimum power. If you have too much quench distance,(more than .060") it can cause a problem. An engine with a 9.5:1 static compression ratio and a poor quench will detonate [which is what LEADS TO pre-ignition] more easily than an engine with a proper quench distance and 10.5:1 static compression.

John C.

[eric414]

IMO i would just do a set of cast heads and save the eddy for a 340 or 360

[jslikness]

The aluminum heads dissipate heat much quicker also which tends to keep down preignition, another reason why you can run higher compression. I say go for it. With that cam in it, it really needs some higher flowing heads anyway. Build up the little '18 and go spank some 340 and 360 tail!

[84ram]

As far as the heads are concerned, I kind of agree with eric414.
I think that unless you are going to be running 11.0:1 or more compression, and a camshaft with a lot more duration , and turning this engine 7500+ rpm, you probably won't ever realize the flow potential of the edelbrock heads. Here are some informative articles to read before you make any final decisions....

http://www.carcraft.com/howto/116_0401_318/

http://kb-silvolite.com/article.php?...s=read&A_id=35

^^^^^^^^
On this page you will find these articles, among others that you may also be interested in reading;

a)Engine building with KB pistons
b)Magnificent Quench
c)Compression ratio vs. Compression pressure.

Hope that helps.

John C.

[threefortyduste]

Originally posted by jslikness
The aluminum heads dissipate heat much quicker also which tends to keep down preignition, another reason why you can run higher compression. I say go for it. With that cam in it, it really needs some higher flowing heads anyway. Build up the little '18 and go spank some 340 and 360 tail!

my thoughts exactly...dont forget that alot of cars nowadays come with compression around 10.5 and some require the 93, but some dont...the LH series cars from chrysler with the 3.5 have 10.5:1, but run best on 89 octane

[Hillbilly]

84ram, thanks for the info. I already have a copy of the Car Craft article and have also considered the magnum head conversion. The only thing stopping me from matching their build up is that I'm not always sure what is realistic and what they embelish to sell the magazine. IMO 400HP is unrealistic without a small inheritance.....now if their build yeilded a realistic 350HP, I'd be game!



I AM
HILLBILLY

[waldo67]

THE EDELBROCK HEADS WILL BE JUST FINE ON YOUR ENGINE JUST BRING UP YHE COMPRESSION THAT IS WHAT I RUN ON MINE TOO AND I BOUGHT THEM FROM HUGHES ENGINES STAGE 2 PORTED AND I AM RUNNNG THE MP CAM 484 284 IN A 67 PLY BELVEDERE THE CAR RAN 13.50 AT 99 MPH WITH 2.02 J HEADS I PUT THE STAGE 2 EDELBROCK AND WENT TO 12.80 AT 104 MPH SO THEY WORK JUST BRING YHE COMPRESSION UP TO 10 TO 1 AT A MINIMUM AND YOU WILL HAVE A BLAST

[waldo67]

sorry dident know caps was meant as shouting

[moparmotorman]

don't you have to "notch" the top of the 318's bores because of the 2.02 intake valve size??

[waldo67]

nope there is plenty of room if your putting 2.02 heads on a 273 then the bores have to be notched

[jslikness]

You ran 12.80's with a 318 in a Belvedere? WOW!!!!

Now THAT is impressive...

[Kevin Garceau]

ok simple question here..... if your going to be building pretty much a new engine, or at least the big parts. Why not just start with a 340 or 360 and put the E heads on it? A few more cubes never hurt anyone, did it?

[eric414]

I agree with Kevin,get a 360 and call it a day.you will very happy

[waldo67]

i agree but if you aint got the bucks to do a new engine and want some experience in the realm of speed then you go with what you got a 318 is just as capable as a 340 or a 360 its all about the combo my hole combo in my 67 belve was as follows edel heads from hughes engines stepped on a bit 484 284 mp cam 10 to 1 compression stock steel crank stock rods stock replacement 30 over slugs i milled the block to get the pow up 391 gears 3500 stall 727 trans turboaction revers man valve body 1 3/4 tubed hoos super comps i drove this car every day the engine had 45000 on it when i pulled it to go bigger so there you go hope it helps