step head pistons on a Super A

Sam Eubanks · Dec 18, 2010

I ordered a rebuild kit for a tractor and they sent me step head pistons rather than flat head pistons. I would like to use the step head pistons if possible rather than wait for replacements. Are they interchangable with the same head?

Stuart · Dec 18, 2010

Yes they will work. If your worried about it, put the pistons in and set the head on it and turn the crank and see. I think others on this site will agree with me about your situation.

gene bender · Dec 18, 2010

No problems just make sure they are installed the correct way or they will hit the head. Your head has plenty of room for them. If they wouldnt work they wouldnt make them.

ScottyHOMeY · Dec 18, 2010

With step heads, the only issue would be clearance under the valves. If you've got the tools to measure, that's easy enough to check, and Stuart's "try fit" is pretty much proof of the pudding. In either, don't forget to allow for the thickness of the head gasket.

The clearance could be an issue with some of the early heads on As, but that issue disappeared by the time of the SuperA. As long as your new sleeves are of the correct fit with your crankcase, I'd say you're good to go.

Brian Schmidt · Dec 18, 2010

A good way to check clearance is using modeling clay or something like that on top of the piston and roll it over with the head on. Then simply use a ruler to push through the clay to the top of the piston to measure the clearance. Then you can also add the thickness of the head gasket. Bottom line if it clears without the gasket, you are good.

Sam Eubanks · Dec 19, 2010

what is the correct fit of the sleeves to the crankcase? are they supposed to sit completely flush to the crankcase when inserted?

ScottyHOMeY · Dec 19, 2010

Sam the larger issue is at the bottom. The distinction is between the vast majority of SuperAs which were built with sleeves that were built with sleeves for a 3" bore that will accept the 3-1/8" overbore sleeves. A comparative few of the last SuperAs, before the SuperA1 which were built with 3-1/8 sleeves (same as the SuperC) that take the sleeves with the 3-1/4" overbore sleeves. The two are not interchangeable.

As far as fit . . . the correct fit is for a snug but not difficult push/twist of the soaped-up sleeves down into the dry o-rings at the bottom of the water jacket. At the top end, having the lip of the sleeve just a tad above flush is the aim, .003" to .007" is the range -- it gives the head gasket a little edge to bite into.

step head pistons on a Super A

Sam Eubanks

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Stuart

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gene bender

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ScottyHOMeY

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Brian Schmidt

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Sam Eubanks

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ScottyHOMeY

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