GT40 to Z304 heads

[carguyohio]

Cannot seem to find a definitive answer. Exhaust ports between the GT-40 heads and Z304 heads. Same height? The Z304 heads are advertised as raised. Not sure if the GT-40 were that way as well? Just concerned about header/pipe exit if I do the swap on a FMS 392 in a Superformance.

[LMH]

Are the Z304 heads the ones that have to use special rockers, pushrods and guide plates?
Seems I remember reading about some heads Ford was making that didn't use standard valve train parts.
Larry

[Paul Kane]

Originally Posted by LMH

Are the Z304 heads the ones that have to use special rockers, pushrods and guide plates?
Seems I remember reading about some heads Ford was making that didn't use standard valve train parts.
Larry

The Z304 is a 20-degree aluminum head that was sold through Ford Racing. Both the intake valve and the intake rocker stud are moved over 0.150". For this reason, a specific intake rocker arm was used that had it's pushrod cup not centered but was located 0.150" back toward the original valve location location since the pushrod remained at the OEM location. This is a brilliant way to offset valves while maintaining correct inline valve train geometry. A picture of such a rocker arm set is attached and you can see the offset pushrod cup (Ice Green rockers).



The exhaust valves of the Z304 use standard rocker arms (Gold rockers).

[vector1]

GT40 exhaust is std height. As long as the bolt patterns are the same the raised should not be a problem, probably only 1/8" or so. I have used the same exhaust on my JBL and everything is tight, from std height to the raised .250" of the AFR220.