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Walter1

Buick piston clearance

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I have bought an engine rebuild kit with Egge pistons for my 48 Buick Super. I live in rural Australia, and my machine shop wishes to know what clearance to give the 20 thou oversize pistons.

The guys at the shop have never seen a straight eight auto block.

Any help appreciated.

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I would give Egge a call also because there pistons may have different tolerances than factory . My 1942 factory manual says at 70 degrees air temp : series 40-50.... .0017"-.0023" desired .0020" then series 60 70 90 ..... .0026" to .0032" desired .0029" . the manual also says compression rings are fitted with a side clearance of .0015" to .0035" , and a gap clearance of .010" to .020" . hope this gives some idea of what your looking for .

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Absolutely, follow "buickkuhn's" advice. Cast pistons such as Egge has traditionally offered (and forged pistons as well) require more piston clearance that the OEM autothermic strut design piston and fitting that type of piston to OEM specs will almost certainly result in problems, badly scuffed pistons or at worst a seized engine.

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Pistons from Egge include a little sheet with each piston that shows recommended clearances. The Egge guy I talked to on the phone when I ordered mine said that was so the machinist couldn't possibly get it wrong -- ha!

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Just make sure Egge includes the CORRECT little sheet for the pistons you buy. Call them to confirm!

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