I'm assembling a spare "rods only" motor for my track-day car. Hopefully, I'll never need to swap it in. I'm thinking that it will likely sit around for a few years and eventually get put into someone's street car.

I'm trying to decide on a good compromise for bearing and ring end gap clearances. With the bearing shells that I have I can get either .0022 or .0027 mains and .0023 or .0028 rod clearance. I'm leaning towards the tighter clearances

The OEM ring gap is .013. I think I could go to .016 and still not have too much blow-by. Anyone have an opinion on this?

 

I opened up my ring gaps when I put my stock pistons back in. Just the top ring. They were around .011 when they came out and i opened them up to about
.016-.018"

Glad I did as the engine now sees 25psi+ on a gtx30. Not really any blowby as its still within stock ring gap clearance.

I went with standard/oem bearing clearances fwiw

 

My current motor is running stock mazda bearings at stock mazda clearances. Rings are super loose, probably excessively so.