Big Block Cylinder Heads - Big-Block Cylinder Head Test

Test Variables
As you've seen, three of the four heads in our test are very close in overall power. One variable that affects any test like this is cam timing. In this case, we chose a dual-pattern camshaft that offers 8 degrees more exhaust duration compared to the intake side. This probably helped the Brodix and Edelbrock heads that had less favorable exhaust flow numbers while perhaps hurting the Dart and TFS heads slightly. The Dart and TFS heads both have raised exhaust ports and strong exhaust flow numbers that likely would have responded with more power by using a single-pattern camshaft. We really can't say that with certainty unless we test this idea, but we have seen results like that with other engines offering high-flow exhaust ports. This is the problem with choosing one camshaft profile for testing multiple cylinder heads. It's entirely possible that the Dart and TFS heads would have produced much stronger peak torque and horsepower numbers had we chosen a single-pattern camshaft. Now you can see why the results of this kind of testing cannot be considered chiseled in stone unless a whole battery of cams go with it. This just gives you something more to think about.

Testing all these heads demanded serious planning since each head required its own specific set of Comp valvesprings and retainers, custom-length pushrods, and ARP head bolts.	Besides burning dozens of gallons of pump gas supplied by Rockett, we also used up a fair amount of gaskets, what with Fel-Pro's oval intake gaskets, the head gaskets, and those slick blue silicone valve-cover gaskets.
We spent a ton of time ensuring that all the pushrod lengths were set correctly to verify proper valvetrain geometry for the Comp Cams roller rockers. These are the Brodix heads, and you can see how the valve-cover rail is rather low.