piston to valve clearance ?

[CRUZIN66]

I HAVE A SET OF FORGED TRW PISTONS (DISHED) IN A 1969 302 SHORT BLOCK WITH A .495 LIFT CAM. i WAS LOOKING AT A SET OF ALUM HEADS WITH 2.02 VALVES WILL I HAVE ANY PROBLEMS WITH PISTON TO VALVE CLEARANCE?

 

[bax]

I would not think you would have any problems with a dish piston and a cam under .500'' of lift. should work all day long.

 

[Broncobowsher]

As there are a dozen different aluminium heads, that is one wildcard we cannot account for.

But typically dish pistons will work with mild to moderate lift cams without a problem. It is also a factor of valve timing. Sometimes heads relocate valves so they don't line up with the valve notches. Many variables we don't know.

I'll say they should work just fine, but to be safe do a quicky clay check one one cylinder.

 

[broncnaz]

You really need to check the clearance out before final assembly. Either put some clay on top of one of the pistons then bolt a head on and rotate the engine then pull the head and measure the thickness of the clay where the valve pushed into it. Or get a checker spring and install and see how much clearnace you have past full lift. Basically you want at least .100 clearance. If the heads you have are trick flows they should work but its always best to check before hand otherwise you could damage something.

 

[BUCKETOBOLTS]

I'd check the clearance just so I could sleep at night. My luck would be that the one what if would be my combination. Besides most factory valve reliefs in the pistons don't always match up with the actual valve position. And like Broncnaz said, if you run the Twisted Wedge heads, the intake valve is in a totally different location than stock. Do you know if the block has ever been decked? And if you ever decide to swap the rocker to 1.7 your lift will increase to around .525 with that cam.

 

[65 mustang]

My rule of thumb was .060 minimum.

 

[jurob]

assuming mild duration. no problem with trickflow tw head because of its design. any other 2.02 head you should check.