I have a B18B bored out .20" over and im putting CP pistons in. The overbore piston rings that came with the pistons are out of spec but under the service limit. The top ring is .55mm. The factory spec calls for .20-.35mm with a service limit of .60mm. The second ring is alot better and very close to spec. Will this motor have blowby, will it burn oil? What should I do? I was about to put it in but im worried.

 

You may loose a little compression too, I would just buy new rings.

 

if your using cp pistons,you should be using the spec. they gave you with the rings,not the factory ones

 

they gave me no specs or instructions with the pistons/rings.