piston slap!!!

twolo4u2c2

5 Year Member
Apr 10, 2003
330
6
29
reading, PA
I recently posted about some sort of weird sound coming out of my 347 when cold and under load. My local engine builder said it was piston slap. I goes away when its warmed up. This winter I'm putting afr185 heads on and am going to check the cylinder to piston clearance. what shout it be? I did searches but cant get a good answer. I have KB hypers in my 347.

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i found a je piston tech sheet. it says piston to cylinder clearence is measured .5 inch up from the bottom of the skirt on the piston. the clearence for a small block should be .0025 to .0035 if your car is nitrous blown or turbo they recomend an additional .001 to .003. thats all i could find hope this helps you.
 
I found it....thanks for the hint on the je

APPLICATION Hypereutectic Forging
Ring End Gap Factor Suggested Piston To Wall Clearance Ring End Gap Factor Suggested Piston To Wall Clearance
Bore To 4.100" 4.100" & up Bore To 4.100" 4.100" & up
Street - Normally Aspirated .0065" .0015" - .0020" .0020" - .0025" .0040" .0035" - .0045" .0045" - .0055"
Street - Towing .0080" .0015" - .0020" .0020" - .0025" .0045" .0040" - .0050" .0050" - .0060"
Street - Nitrous or Supercharged .0080" .0020" - .0025" .0025" - .0035" .0050" .0045" - .0055" .0055" - .0065"
Circle Track - 2 BBL or Restrictor/Gas .0070" .0015" - .0045" .0020" - .0050" .0040" .0040" - .0050" .0055" - .0065"
Circle Track - Unrestricted .0080" .0025" - .0045" .0030" - .0045" .0040" .0045" - .0065" .0055" - .0075"
Circle Track - Alcohol Injection .0060" .0025" - .0045" .0025" - .0050" .0040" .0045" - .0065" .0055" - .0075"
Circle Track - Alcohol Carbureted .0080" .0030" - .0045" .0030" - .0050" .0045" .0050" - .0070" .0060" - .0080"
Drag - Gasoline .0075" .0015" - .0045" .0020" - .0045" .0040" .0050" - .0070" .0060" - .0080"
Drag - Alcohol .0065" .0015" - .0045" .0020" - .0045" .0040" .0040" - .0070" .0050" - .0080"
Drag - Supercharged or Nitrous Gas .0095" .0020" - .0045" .0025" - .0050" .0050" .0060" - .0090" .0070" - .0100"
Drag - Supercharged Alcohol .0085" .0015" - .0045" .0025" - .0045" .0050" .0050" - .0070" .0060" - .0080"
Drag - Supercharged Fuel .0115" .0030" - .0050" .0035" - .0055" .0060" .0070" - .0100" .0080" - .0110"
Marine - Normally Aspirated .0080" .0030" - .0045" .0035" - .0050" .0040" .0045" - .0060" .0055" - .0070"
Marine - Supercharged .0090" .0030" - .0045" .0035" - .0050" .0045" .0055" - .0070" .0065" - .0080"
Air Cooled Baja .0075" .0030" - .0045" .0035" - .0050" .0040" .0050" - .0070" .0060" - .0080"
Propane .0065" .0015" - .0045" .0020" - .0045" .0040" .0035" - .0070" .0045" - .0080"
Supercharged Monster Truck / Mudbog .0090" .0025" - .0045" .0030" - .0050" .0060" .0080" - .0100" .0090" - .0110"