Topic: Quick general piston ring question....

[SClay115]

...This is really a very 'noob-tastic' question I have. But while pricing out rebuild options for my engine, not a four cylinder, but I know all the guru's hang out in this forum. But I am looking at options, as I need to get my cylinders bored out, there are some nicks and such. I was under the impression that when getting OS(oversized) rings, one needs to use OS pistons...

I have since been told that you can run OS rings on factory pistons..their job is to take up the space you just made from boring out the cylinders.

How much truth is in this statement? And is this even a suggested practice? There is no real 'middle ground' for piston availability, it's either cheap knock-offs, or hi-comp forged pieces, and this might seem like a viable option, since there really isn't anything wrong with the factory pistons, it's just the cylinder walls themselves...

Steve

[mark]

Oversize pistons and oversize rings go together like 'cuff' and 'link'. I have never seen anyone wear cufflinks on a t-shirt.

If you bore the cylinders, you will need larger pistons to fit. It is the job of the piston to fill the cylinder - the rings merely serve to keep the combustion process out of the crankcase.

Without seeing the actual condition of your cylinders, it is difficult to make a proper recommendation.


Happy trails.

[rhinoracer]

The pistons are supposed to fit into the bore at the specified tolerances so it slides up and down perfectly straight inside the cylinder.

If the cylinder is any larger it will allow the piston to slant (rock) inside the bore, with the crown making contact on one side and the skirt on the opposite of the cylinder wall. Now if you can imagine what goes on inside a revving engine, that cannot be good.

[SClay115]

OK good, then I wasn't going nuts before. I thought that was the way it worked as well. Thanks guys for the reassurance.

Steve