# 400 Heads and pump gas CR



## 15mitchleis (Feb 6, 2016)

Hi everyone new to the forum and was needing some opinions. I have a 72 400 that has 5000 miles on a rebuild but the guy I bought it from put 4x heads on it with 111cc chambers. The problem I have is it doesn't have any get up and go. I'm looking at buying a set of 72cc edelbrock heads to swap on but wasn't sure if I could get away with it or not. Alot of guys have said that it would have a CR of 10:1 which is high but aluminum heads wouldn't knock how true is this.


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## oldskool (Apr 26, 2015)

Welcome to the site ! 

And, yes, the 72cc alum heads will work very well on a 400. 10.5 CR is said to be safe with pump gas, when running alum heads. 

I think the 74cc KRE D-ports will be cheaper than the E-heads, new. 

Kauffman Racing Equipment

But, if you need an exhaust heat crossover, for cold weather driving, the Edel D-ports have the provision for it. I've read that if you buy new E-heads, you should buy from a Pontiac vendor, who takes bare E-heads, then installs better parts, than what comes from Edelbrock. 

Butler Performance - Edelbrock Aluminum D Port Pontiac Cylinder Heads

Another thing to consider is using smaller chamber iron heads. The main reason you have no power is that those 4x heads were off a 455 engine--never meant for a 400. It probably had less than 7:1 CR. 

Then later 400's with 6x-8 heads had 7.6 and with 6x-4 heads had about 8:1. So, with some 6x heads, thin head gaskets, and a small Voodoo cam, you can increase power quite a bit. 

But, if your engine was built with the cheap 8-eyebrow(valve reliefs) pistons, you might come out better going with the alum heads, since they tend to help reduce the chances of detonation.


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## 15mitchleis (Feb 6, 2016)

Hey thanks for the fast response do you know if the kre heads would use my existing brackets and the e heads I'm looking at are from butler they're suppousidly ready to bolt on for 2400 does that seem pretty fair I'm trying to do it on a budget marines don't make shit lmao


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## oldskool (Apr 26, 2015)

15mitchleis said:


> ...the e heads I'm looking at are from butler they're suppousidly ready to bolt on for 2400 does that seem pretty fair I'm trying to do it on a budget marines don't make shit lmao



Those $2400 heads are box stock, from Edel. And that price does not include the bolts or shipping charges, I don't think. 

But, if price is a big deal, you can probably go with 6x heads for about half the price. You don't really need the high $ porting that some of the big shops will try to sell you. Just need new stainless valves and a good, complete valve job, done by a competent Pontiac head shop.

Butler tries to sell ported heads, but will build 'em any way you want 'em, I assume. The porting is just not needed, unless you wanna make big power, with a larger cube engine.

Butler Performance - Pontiac Cast Iron Head Labor Prices

Total price for cores, parts, and labor should be under $1000, if no porting is done. The thin gaskets are about $200. And stock head bolts will work. There are usually some cores and ready to bolt on heads, on some of the Pontiac forums. PY is a good place to look. But, as with most any other sites, you can't be assured that the seller is telling the truth about what he has.  There are several good Pontiac engine guys on PY, who can build you a good set of 6x heads. 

Without being milled some, the 6x-8 heads will usually have 101cc chambers. But that's a lot better than your 111cc monsters. And you can have equal amounts cut from the chamber and intake sides of the heads, to increase CR some. 

6x8 heads fresh from shop . - PY Online Forums

Pontiac 6X-8 Heads: Fresh 2.11/1/77 - PY Online Forums


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## 15mitchleis (Feb 6, 2016)

OK I emailed kre because they're in my home state money's not a huge concern I just want it done right for as cheap as I can. Also I'm trying to get something bolt on and go because I'm going home towards the end of April and just want to get it out and enjoy it some. I'm not too concerned with power because it's in a 66 bonneville but would like some balls. I really appreciate all the input.


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## oldgto66 (Dec 31, 2011)

I got a set from KRE about 6 months a go 74cc,Ferrea valves, valve job, guide clearance to 1.65, ARP rocker studs,ready to install, for $ 1,965.00. Talked with Jeff, told him what I was looking to do. He told me what I would need, great company to work with.


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## oldgto66 (Dec 31, 2011)

I have to apologize. I pulled out receipts and the price was right , but it was 16 months ago that I bought them. Boy how time flies as I get older!


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