replace pistons

Becks Bear, if you can find a local engine re-conditioner they may have a bore ovality gauge and may come out to your vehicle to measure the bore. You may also be able to find someone with a ridge reamer who could remove the ring ridge at the top of the cylinder.

zzr1200 said:

Becks Bear, if you can find a local engine re-conditioner they may have a bore ovality gauge and may come out to your vehicle to measure the bore. You may also be able to find someone with a ridge reamer who could remove the ring ridge at the top of the cylinder.

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Some folks say to leave the ridge alone and use ridge-dodger rings.
They say new head gasket will be safer this way.

But if the head gasket has enough leeway for the enlarged bores or removed ridge you will be OK.

Just another point to keep in mind.

CharlesY

Another thing that you could try out (just to be absolutely certain that you're doing a good job) would be to buy a set of new standard size rings and then push one down into to the bore. If the piston ring gap is excessively large (definitely anything over 3-4MM or so), buy the next size up and then file the ends down slightly so that they're a tighter fit - don't forget that the bores are tapered, and are slightly narrower towards the bottom of the block. I simply deglazed, and fitted all new standard parts to my N/A (all Britpart) and I didn't remove the ridge, or fit ridge dodgers either. I've had the head off three time since the rebuild for other bits and bobs and it's running better than it ever has done now. The Britpart pistons and rings are also all still in one piece with no cracks!

-Pos

VERY dodgy not taking account of the ridge!
The risk is breaking off the top land of the piston, the bit of piston right under the top compression ring.

You might be lucky. You might not be.

In principle, always take account of the ridge, and make allowances.

CharlesY

CharlesY said:

But if the head gasket has enough leeway for the enlarged bores or removed ridge you will be OK.

CharlesY

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Agreed.

I've never seen a head gasket specifically for a re-bored engine or one ever listed in parts lists.

I am trying to cast my mind back .... and I think there were special head gaskets we had to use on the Cooper "S" Minis that were bored plus .040".

But I think that was because the two centre cylinders were so close together.
Siamesed cylinders they called them - no water jacket between them.

Landy Engines are designed with a bit more space.

CharlesY