Topic: Questions about piston ring size.

[yesplease]

Assuming the piston ring grooves were within spec, if the bore was worn enough but still round, could I file fit oversize rings in order to get the proper clearance w/o getting everything bored out to the next oversize and having to buy new pistons? Not something I would expect to last another 500k miles, but just to get something back on the road. Hopefully someone has some experience with this, but any comments/ideas are great.

[USN20]

What engine are you referring to?

Generally speaking - No

File fitting oversize rings will have increased radial tension beyond their design. Increased tension will lead to increased friction and the rings will run hotter and will most likely break. Also expect the rings and bore to wear much faster. Cylinder taper has a pronounced effect on how much the rings will flex. It can be done, but it's not recommended. If you have no other choice and proceed, the least you can do is operate the engine under reduced RPM conditions to avoid additional ring stress. That is, in my humble opinion.

[754]

Run the right size rings and have a bit better comp than what you had..

[yesplease]

The application is an IDI diesel, 4k rpm max. I found this which I think says that radial tension can be decreased by machining slightly thinner ends... Any idea if that'll work. I'm just trying to get by for ~20-100k+ miles instead of going to oversized pistons ($300!).