HELP! 302 problem *please read*

[dentside7977]

this is a little far off from an old ford truck but i figured someone on here may have a clue.

alright guys, heres a doosey for you. i hope someone can shed some light on this...

The original planned setup:

1990 H.O. 302 shortblock. bored .030. Stock crank, stock rods. stock compression pistons. No deck work on the block.
1995 Cobra GT-40 heads. stock valves, no milling
1995 Cobra 1.7:1 roller rocker arms. Factory ford part made by Crane.
Ford Racing "F" cam. .512/.512 lift, 288 duration
Trickflow high lift valve springs.
Comp Cams double roller timing set.
Lunati direct replacement stock 6.4 inch pushrods
Lunati direct replacement stock lifters

should work right? well the pistons hit the valves BAD. i double checked my timing marks and they looked good. i removed the 1.7 rockers and installed a set of stock 1.6 rockers and i still have BAD piston to valve clearance.

I think "damn, the cam is too big" so i went back to summit and returned the F and got a B cam instead. .480/.480 lift, 284 duration.

I STILL have clearance problems. i then thought maybe its something to do with GT40 heads so i bolted an E7 head on and STILL had the problem.

i double checked the timing marks, theyre perfect and i double checked to make sure they gave me the right set. they did.

so...where do i go from here?

[tybob81]

Your pistons are possibly to tall or dont have the proper valve relief for your configuration. If they can be relief cut that is an option.

[fomocoguy]

Do your pistons have valve reliefs cut in them? I've seen people install factory flat tops from the 86 engines to up the cr a bit, but it severely limits the amount of lift you can add over stock. All stock pistons from 87-up should have reliefs cut in them.