440 hi comp piston hit valves

[chad400]

anyone ever have this problem? went from a 416 11:1 to a 440 12.5:1! motor had a noise so we took it back apart to find marks on the piston from both the intake and exhaust valves.!!! tomorrow i will take piston to get fly cut . did not hit hard enough to bend valves but .............ever heard of this problem? by the way i am useing a hot cam stage 1 and a hot rod!

[MIKE400EX]

Maybe the cam timing was a tooth off? Check the valve spring pressure too, weak springs could allow the valves to float. That or the pockets weren't milled deep enough to start with.

[Barney]

I had problems in this area. Only way to check this is to clay the
piston when you assemble the engine to check for clearence
between valves and piston. And if you have to make the pockets
bigger in the top of piston so valves don't make contact.

[shamisc]

Do you have another pic? This one didn't work!:(