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Ring gap for 85.5 standard bore?
bigdave - June 6th, 2011 at 06:56 PM

What is the recommended piston ring gap or tolerance before it is time to throw away?
Cheers
dave

grumble - June 6th, 2011 at 07:17 PM

The recommended ring gap was .004" per inch of bore. Obviously if the bore is scored or lipped badly it is time to replace the units. When we are rebuilding normally we replace the pistons and barrels, this is the same as reboring an inline motor.

68AutoBug - June 6th, 2011 at 11:45 PM

Quote:
Originally posted by bigdave
What is the recommended piston ring gap or tolerance before it is time to throw away?
Cheers
dave


Hi Dave,
I'm not an engine rebuilder but that is a strange request ...
it depends on the manufacturer of the rings I would say...

usually Pistons with new rings and cylinders are replaced all together...

check if there is a lip in the cylinder ...
where the rings don;t go -
this will be the original size of the cylinder...

You should be able to feel the lip with Your Finger...

cheers

LEE

vwo60 - June 7th, 2011 at 01:08 PM

The ring gap is a major part of any engine build, you cannot trust any manufacturer , these need to be checked and filed to the correct gap when you install any piston rings,
Compression ring clearance new - .3MM to .45MM.
Oil scrapper ring clearance new - .25MM to .4MM.
Wear limit compression ring - .9MM.
wear limit oil scrapper ring - .95MM.
sizes taken from the factory manual

matberry - June 7th, 2011 at 08:50 PM

I recommend .0045"/inch of bore for our engines