Archimedes

I have 2 sets of heads. I have 2 289 heads with adjustable rockers, and 2 302 heads with fixed rockers that are paired in the head. My question, I have a 302 engine, will I lose power/performance using the 289 heads since they are more clean and and the rockers can be adjusted, or, should I clean up, convert rockers/studs and keep using the 302 heads which are pretty dirty from carbon deposits. I am using a GK High performance camshaft also so it requires valves to be compressed more and all that. Thanks for the help.

Dan - 67 Mustang Convertible "Destiny"

302xm

It depends on the casting no.s of the heads as the later heads have larger combustion chambers which will drop/raise compression ratio depending on whatyear your motor is and pistons your using
The only benifits the 289 heads have compaired to 302 heads of the same era are the slotted pushrod guides (saves on installing guide plates).
You can use just about any 302w,5.0 head's with a bit of research.
Id reccommend checking your valve-piston clearance with whatever head u decide to use because of the increased valve lift,its pretty straight forward and will save a costly mistake down the road.