Can 15* pistons

[bumpdrafter]

This might sound like a stupid question but can 15* pistons be used with 23* heads?

[dynoman14]

A good engine builder can easily lay out the valve center lines on both pistons and determine where the valve pockets are located in each piston and tell you what will work.

Depends on where the valves were in the 15* head that the pistons were designed for. Best thing to do is clay the tops of all 8 , install the heads with valves light springs, rockers, lifters and pushrods and rotate them thru a couple engine cycles by hand and then take the heads back off and look to see where the valves hit.

In many cases you can run a lower degree piston with a higher degree head. Some Clements have the valve locations move and the CL's of the 23* will cause them to hit the valve reliefs in the corners.

If the centerlines are OK, A lot of it will also depend on the camshaft your run, total lift and how much the camshaft is advanced, cause rolling the intake CL from 110 to 100 places the intake valve way closer to collision with the piston.

I like to see a minimum clearance of .125" on the intake and .100" on the exhaust.

If you can't get it done where you are you can send a left and a right piston from each set and your camshaft and I can send you the info back. It will cost way less than the problems that will occur if they are not right.

PM or e-mail me if you have any further questions.

[fast_crew]

Why so much p/v clearance needed? Really only need .050-.060 or so on intake and .080 on exhaust. The intake valve is chasing the piston and on the opening ramp, (unless the engine is spun backwards)