Standard piston rings on oversized pistons?

[ziggo0]

I wasn't originally going to be doing a mini rebuild but I figure while the engine is apart, re-ring it. I have a brand new set of rings for std size bore pistons, but the pistons in my engine are 1mm/0.040 over. Would the std rings work on over bored pistons? If not I'm more than prepared to get new rings, I figure saving a few bucks though wouldn't hurt.

 

[eeeewidner]

Come on man. You know the answer to this question is no.....That question is an easy way to get flamed....

 

[tkelly27]

Well, try it. If you're trying to run a big gap and the ring manufacturer made them tight from the factory you may be able to get away with it. I wouldn't plan on it. You could probably do the math and see what kind of gap it's going to give you, I'm not about to do it for you though.

Did the math. Answer is no. Circumference of an 85mm bore is 266.9mm and an 86mm bore is 270mm. Being that the ring gap is in the range of .5mm you're gonna be way off.

 

[eeeewidner]

well, try it. If you're trying to run a big gap .

No kidding.

 

[ziggo0]

As I stated I have no problem paying for the correct sized rings...I figured I would simply ask just in-case they could be used...no harm in asking a simple question....

 

[DSMGraveyardinc]

Please let me help!!

Your best bet for doing a half rebuild, your going to want to use at very very min, new rings, and new bearings AND correct sizes otherwise you are wasting your time.

Also your rebuilt should be based on what made you tear it down in the first place. If you had rod bearing failure, or if you had bad compression, usually would point you in which repair build you do. (Notice I did not say RE build).

I would REALLY love to help you with tech!! We are making a Basic "What to Do" and "What NOT to Do" on our site this spring, and you would probably really get a lot of knowledge from it. It is under our new "QuickSpecs" Category on the main page.

Feel free to call in, we are here for you guys!

Jon @ DSM Graveyard

DSM Graveyard's Engine Building Planner

What NOT to Do ( Non 100% Finished)

 

[BogusSVO]

keep this in mind too.... for every .001 you open the bore you gain Pi (3.141) on your ring gap so with a .040 over bore X 3.141 = .12564 plus what the "built in ring gap" is so you would be appox .145 ring gap.... I would say thats a bit much...

also the arch of the ring will be diffrent from std to .040 so ontop of blow by, you would have even worse ring sealing issues....

so get the proper over size rings......