Edelbrock to Shelby head swap

[FE Specialties]

Hi Doug,

You have gotten some good replys to your post!!
The Shelby heads flow good on the intake side, but the Edelbrocks have a better exhaust to start with!!
I am concerned with your compression with your motor!! If you put the Shelby heads on, you will lose about .6 in compression, down to about 9.9 to 1. This will do more to hurt your performance than the increase in flow. Also, what intake are you using? If its a dual plane, such as a performer RPM, then the intake will have to be flowed to match the capacity of the heads to acheive the desired results. The head is just part of the intake tract!! Definetly a precise port match is needed.
The bottom line is really what your trying to accomplish. How much power are you trying to obtain. If your looking for about 500 HP, then either head will suffice!!
We are coming up with an offset rocker with 5/16 pushrods that will let us go about 1.75 wide on the intake port on the Edelbrock heads. This will equate out to the 380-395 flow numbers that are so sought after. But these kind of flow numbers are for full on drag motors, and will be a little lathargic on the street. Remember, in a Cobra street application, your looking for the highest Average torque and HP readings with a wide RPM band between peak torque and peak horsepower!!
I would blend port your Edelbrocks which would get around 325 cfm without increasing the port volume too much. This builds a wide torque band and makes the engine a real joy to drive on the street!!
P.S. With aluminum heads, you need to keep the compression to at least 10.6 to 1 so the motor stays effecient.
Hope this helps!!
Tom Lucas FE Specialties