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How would I determine if the pistons in my 1960 Super 90 are original? I'm tearing down the engine, and am curious if it has been rebuilt previously. So far, everything has appeared original. Consistently dirty. Correct fasteners and sizes (per Harry Pellow). Though I'm guessing these pistons are not. They seem pretty clean on the outside, and the bands around them seem out of place.

Those are not stock, probably MC racing pistons with a pretty high dome.

Martin Benade wrote:Those are not stock, probably MC racing pistons with a pretty high dome.

Thanks Martin. As I feared. Not the all original, unmolested engine I was slowly gaining confidence in. Oh well. Further justification for a complete overhaul. Also makes me feel less guilty going down the big bore kit route, instead of all original spec.

Nothing to feel guilty about. Build it that way that pleases you. It is nobody else's concern what kind of pistons you have.

Those MC pistons will rattle like marbles in a coffee can when cold. For you young guys, coffee cans used to be made from steel.

Vic Skirmants wrote:For you young guys, coffee cans used to be made from steel.

Martin Benade wrote:Those are not stock, probably MC racing pistons with a pretty high dome.

Good call Martin. After I got them out, I was able to find an "MC" mark inside one of them. Nice to know what to look for! Thanks.

MC rattling is right. When the 86mm Shasta pistons first came out, I sent a nice set of original barrels and the pistons to Ray Litz. He did not believe that the Shastas could run the tight clearances specified and machined the barrels like he did for MCs. They rattled like crazy!! I asked Duane Spenser about it at the 1998 WCH and he started his engine. *quiet*

I had a set of worn out MCs in a hot rod engine years ago. It used about 5 quarts of oil on the 90 mile trip to an autocross. It was extra noisy because the Scca cam and stock springs let the exhaust valves hit the pistons at high revs. They left obvious marks but nothing got bent. I sure was dumb! Probably nearing 80 hp out of my cleverly modified S90.

" Probably nearing 80 hp out of my cleverly modified S90."