Piston to wall clearance.

Hey guys. Have a question about piston to wall clearance.Just bought a set of new 40 over forged mahle pistons, ( 4.040 bore) and was wondering what people recommend for wall clearance. I talked to 2 different shops and got 2 diff answers. The pistons didn't come with any clearance dimensions, just said use what your shop recommends.It will be run with a rochester 2 barrel and will be around 275 to 300 max hp and spinning 6700 max. Usually runs about 200 degrees in feature, and im using the ring pack 1.5 1.5 3.0
that mahle sells with the pistons. Any info would sure be appreciated.


Thanks alot.

Round track should be. 005-.006

Thanks for the info Perf. One shop said .006 and one said .035.I will set it up like you are saying.

.0035 will not work on circle track.You would end up scuffing pistons.

If those are the Power pack piston Kit they are built to fit a 4.040 bore as the clearance is built into the pistons. Those pistons are made out of 4032 material and don't expand like a piston made out 2618 material, Don't fit those pistons like you would fit a piston made out of 2618 material.

Make sure you block is plate honed using a good hone and cylinder finish is key. 4.041 should work fine for you application.

I have used quite a few sets of those pistons in circle track engines with no problems.