A7 rebore size

[Tiger]

Hello people
Anyone know the max rebore size for 3 bearing Ruby ?
Regards
            Tim

[Chris KC]

Tim,

+0.060 is generally considered a safe bet. If you are lucky they will go to +0.080, but there is variation from block to block and you may break through into the water jacket. They can of course be sleeved.

I would suggest checking available piston sizes first, as we now have metric size increments available as well as imperial. Ideally remove no more material than the next available piston oversize, if the bore doesn't clean up then go to the next.

So far as I'm aware same is true of all A7 blocks.

I would suggest giving the block a good look over for cracks / damaged threads / sheared off studs / blocked cooling jacket (etc.) and address these before spending money on machining.

[Tiger]

Thanks Chris
Already bored to +0.060”

[Charles P]

Thanks Chris
Already bored to +0.060”

Bear in mind that modern metric sports pistons have odd steps. These are no problem in touring engines. 
Mine engine is now at about +73 thou but as was said, over 60 is at your risk but there are lots of engines at +80

Charles