H piston

Jim Isler · Sep 29, 2011

I need to replace one broken piston and when looking up parts, they say "overbore to 3 7/16. Do I have to replace the sleeve too? Or will the larger piston fit when I hone the current sleeve, which looks fine.

Janicholson · Sep 29, 2011

The piston must match the sleeve. Measure the bore pretty acurately and purchase a piston for it. If the sleeves have a ridge that you can easily feel with your thumb nail, it probably needs sleeves and pistons. An overbore (really just using thinnwer sleeves will add power and cost no more than original new parts. Jim

David G · Sep 29, 2011

Jim,

You do not want to have the one piston a different size from the others.

DeltaRed · Sep 29, 2011

Hey Jim,I can help call me .874-3973.(I'm only 20 miles away).Do you know who I am?Steve.

JRSutton · Sep 29, 2011

agreed - it will probably work "ok" - but you do throw off the balance of the crank - in many ways.

Might not matter so much in a low compression/low rev tractor engine, but if it were me I'd either try to find the standard size, or change them all. If you're doing one, doing 4 isn't all that much more work.

Then they're all done and you don't have to worry about any of them for another 50 years.

mkirsch · Sep 30, 2011

(quoted from post at 13:39:01 09/29/11) I need to replace one broken piston and when looking up parts, they say "overbore to 3 7/16. Do I have to replace the sleeve too? Or will the larger piston fit when I hone the current sleeve, which looks fine.

You know, it depends on what you currently have...

That means you've gotta measure your existing bore. The engine could have been rebuilt with the overbore pistons at any time in the last 72 years.

Pistons come in many sizes. Most people when they rebuild an H put in overbore pistons and sleeves for more power.

H piston

Jim Isler

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Janicholson

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David G

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DeltaRed

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JRSutton

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mkirsch

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