My machinist suggested that the piston clearance should be a little looser than stock speck on the engine I'm building if I want to race it. I was thinking around .0015 ". What is my best bet? I want to race this car, but I want it somewhat streetable. The engine is .060 overbore, with .502 lift cam from Comp Cams, and I'm expecting 10.5:1 compression.

Thanks.

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65' Dart. A work in progress..
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Joe

Mine are cast replacement pistons (TRW, 0.060) and they are set to the loose side of factory, but that's all I remember. I also used lower tension oil rings, and it only uses 1 qt every 1k miles, or a little less after 45k miles and lots of racing. 6k RPM, no problem...

Lou

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Home of Slant6-powered fun machines since 1988

It really depends on what type of piston you are using. IIRC, forged pistons need to be looser than cast, and hypereutectic can be about the same as cast. My Slant manual calls for .0015"-.002" for stock pistons.

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Official Cookie and Mater Tormentor.

We just installed a motor with forged 2.2 pistons set at .003 clearance.
I have not started the engine yet so I can't say how it works, may-be next week.
DD

I guess I'll just tell him to make it happen. He has built many successful race engines, and is a well respected machinist. Thanks for the input guys.

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65' Dart. A work in progress..
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Joe

You did, or the kids did?

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'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG

Know how they always build a better idiot? That's me