The pistons are based on a cast taken of a vert chamber. I've never worked with a sloper head, so I'm not familiar with the chamber differences, I know Aaron has researched it some. I figured anyone investing in pistons of this nature would be running a vert head...kind of a waste using them on a sloper head.
I'd guess the squish area is the only area where contact might occur, I think the sloper chamber is a bit smaller in diameter where it tapers down to the bore size. Note on a vert head there is a chamfer around the base of the chamber...I think this chamfer is less pronounced on the sloper (if I remember Aaron's info correctly). It's all moot if the engine is assembled with care taken to measure clearances. My notes show acceptable squish to be .040"...so if that's maintained then there shouldn't be problems regardless of the head used....assuming it's never been milled.
These are race parts, made to be installed in race engines, and of course in race engines NOTHING is left to chance. If squish is too small it's a super easy fix...thicker head gasket or additional base gaskets. Take copious notes, record clearances, track changes.
Aaron I think figured that these pistons made quite a bit more compression in a sloper head than a vert head. Could have been one of the reasons he was having issues detonating pistons or melting heads. The sloper head just isn't designed to handle the heat produced in a high compression engine I don't think. Of course a .010" squish would certainly build some more compression...specially locally on top of the ring land...which could have lead to his piston melting problems at Daytona.
Throw the sloper head away, vert heads are a dime a dozen and a stock one breaths as well as a ported sloper head. More finning, better valve seats, better port angles, just a better piece all around.
JohnnyB
