How to choose the right cylinder head?

#1
Gentlemen,

I´m seeking for some advice on how to choose the right cylinder heads, particularly how to determine the correct combustion chamber and intake runner volume.
There are so many choices that I´m a bit puzzled.
Engine is a BBC GenIV with a BBC Kinsler/Lucas mechanical injection, rectangular intake ports.

Any advice highly appreciated. Many thanks.

Best,
Marcus
 
#3
David,

it is a ZL1 block. Depending upon the yet to choose rotating assembly it is going to end up between a 427 and 454 CI.

Best,
Marcus
 
#6
Do you mean GM heads or aftermarket heads? There are a lot of comparisons available in books and in tests done by engine builders comparing various heads,with dyno runs to show the results. For BBC engines in street use, oval-port heads seem better than rectangular port heads, from what I've read. There may also be a local race engine shop to give you suggestions. AFR, Edelbrock, TF, Brodix, WP all make good heads. Among other, no doubt.
 
#7
Jim,

thank you. The design of my Kinsler intake manifold requires rectangular ports.
Don´t need to stick with GM heads, though. Had a close look at AFR heads for BBC,
they do look promising but they can be supplied in many variations. Dave´s hint has been a great help so far because it made me find out that the original GM heads for a ZL-1 engine back in 69´had a combustion chamber volume of 118 cc.

Maybe you could recommend me some books or magazines where I can find the various comparisons and tests you´ve mentioned. I appreciate it.

Best,
Marcus
 

Brian Kissel

Lifetime Premier Supporter
#8
Hello Marcus !!

Here is a little info on AFR's heads. Just go to the BBC section.

Air Flow Research

Here is a comparison of various heads also from this site. Done in the Chevy High Performance mag.

Chevy High Performance BBC Shootout

Remember, the smaller the runner, the better responce, as long as it is properly size for your engine. At one time, I didn't think there was a better head out there than Dart, but I'm thinking AFR's might be the right setup. To each his own, for ones personal project.

Kindest Regards
Brian
 
#11
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#12
Marcus,
The AFR database tells only half the story. It was either in Fast Fords, or Popular Hot Rodding that did a shoot out on flow characteristics of AFR vs twisted wedge vs stock heads vs several others, at the different levels of flow/size etc. May have been on Ford engines. The point is that they gave some good numbers and which was the better performer etc. The stock heads even the HiPo heads served as a basis of comparisons as they couldn't compete with the aftermarket boys. I thought I had the articles as they were spread it out over several months/issues, but I couldn't find them. The AFR articles are a good source though. Just remember if you stick with carb(s) you can't go too large unless you plan to track the car, as with big ports, the vacuum goes down.

Bill
 

Woody

New Member
#13
Hi Marcus
Your question may not seem complex but the answer sure is. The math that goes into choosing combustion and runner size is more than I can one finger type in a day! With out trying to get too complicated, your combustion chamber size is determined by the cu-in of the engine and the fuel you run. Heads perfect for a 427 will have far to small a chamber for a 454. The intake runner size is governed by your camshaft or how much air the cam and valve size requires or vice-a versa you chose you cam to suit your heads. Your injection manifold plays a very big part in this as well You need to know the size of the butterflies and not the ones in your stomach after reading this gobbly gook but the ones in the throttle body. All the parts work together as a team. If the injection manifold is to big for the cylinder head runner volume the engine will lack torque and feel soggy untill the air speed /RPM gets up. And so-on and so-on untill you have no hair left. My advice to you is to talk nicely to your local engine shop, they should be able to work it out. A lot of shops have computer programs that do the math for them. This however is only a good start because nothing beats experience. Its worth getting right. Guys will say "there's just somthing about Marus's engine it sounds so sweet"
Have fun
Woody.
 

Jim

New Member
#14
Hi Marcus,
Are you sure you have the right web site? Big Block chevies belong on pick up truck web sites. If you stuff a chevy engine into a GT 40, I can't imagine any resale value. For that matter, class A motorhome buyers don't even consider the big block chevy. The 460 FORD is the reliable engine of choice. How about an all aluminum Ford 427 Widsor Racing crate engine that makes 600 horsepower. You can buy it from Fordracing.com. This awesome engine is all aluminun weighing 150 pounds(70 kilos?) less than a bbc.
Just tryin' to look out for ya!! Ranger Jim
 

Brian Kissel

Lifetime Premier Supporter
#15
Jim

Marcus is building a Lola T70 mk3b. As he stated, he has a aluminum ZL1 block. There were far more Chevy engines used in the Lolas compared to Fords.
At one time, he mentioned he might use a Roush 427 to toss out as a emergency brake however.

Regards Brian
 
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