This is exactly what I went through. I went from stock heads with 54cc chambers to Edelbrocks with 60cc and went from 305 RWHP to about 217RWHP with a Edelbrock RPM cam, Performer intake and 600 carb. Edelbrock claims 367 FWHP with their package and in small print recommends at least 9.5 CR (which I was told there were other changes). But my numbers were almost identical with no other changes other then the heads.the first thing you need to do is determine exactly what your current compression ratio is, and work from there. since your engine is already together, you can make a few assumptions that can be corrected later if need be. the first thing you need to find is a good compression ratio calculator on the web, someone here will have a link to one.
the next thing you need to know is the combustion chamber volume. with the edelbrock heads i believe that is 60cc, but check to be sure.
most pistons are down in the bore about .002", chances are the compressed thickness of your head gasket is .053", so when you use the compression ratio calculator, you can plug those numbers in along with all the others required.
i suspect that your compression ratio is going to be around 8.5:1, and you want it to be around 10:1. once you have the compression ratio calculated, you can play with the numbers to figure out how much you need to shave off the head to get to the compression ratio you want.
If you look on top of the post, I just got the car back from tuning. Timing was of course also checked.
The carb is fine for that cam. The comp guy was dead on given the cam selection. Now if you go big on the cam and higher on the RPM then the carb is limiting but not by much. The hP exhaust manifolds are every bit as good as shorty headers. I've been there and done that. Buy the bigger carb and add the shorty headers and I garantee you will be disappointed. You will gain nothing.I don’t see an engine size.
If it is a 302 and your pistons are not flat tops you need to mill a lot off of the heads.
If it is a 302 with flat tops you need to machine the heads to 57 cc’s.
You need to measure how far the pistons are down in the bore at tdc. . you need around .040 clearance between the top of the piston and cylinder head . . adjust this clearance with thinner head gaskets from cometic.
Those heads come with either 1.90 or 2.02 valves, which ones are they?
try a 1/2 to 1 inch spacer under the carb.
Buy a 600 cfm quick fuel vacuum secondary slayer carb or an ss style if you have more money . . the comp cam guy is an idiot 500 is too small.
that is also a horrible cam for those heads.
Buy 8, 1.65 or 1.70 rocker arms for the exhaust.
Set your valve train geometry.
Plug your distributor vacuum advance.
set your idle timing to 12.
Set your total timing so it reaches a max of 32 degrees btdc at around 2600 – 2800 rpm.
1 1/2 inch tube shorty headers will be a little better . . hedman elites are good.
you need at least 3.23 gears, 3.40 would be better.
the mustang dynos read lower than most . . another type of dyno would show around 25% more power.
So what are the differences between the roller cam and flat cam heads. I suspect mainly a different spring, but please enlighten us!
We found out what was wrong. The Edelbrock E-street heads they gave me with the roller cam was not meant for roller cam!
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