I am currently going through my 350. I am trying to install my pistons but my oil control rings seem to be too large for the bore, they go in but they need massive force to go into the bore. I took off the oil rings and left the two compression rings and the piston goes in great, so the problem is definately the oil control rings. The groove is also spotless. They are summit brand rings, which I think are pregapped, but the oil rings shouldn't need to be gapped anyway. Should I file then down?

 

We just got finished rebuilding my friends 302 (ford), and on his ring box, they were sealed power i think.... but anyway, it said not to compress the oil ring, until they were ready to install in the bore.

Sorry this dont help much. hopefully someone else will chime in

 

Stick them down the hole, off the piston, one at a time, square in the bore and measure the gap.

I've had oil rings that weren't the same size as the compression rings (not Summit, by the way), except it was the other way around (.020"-over rings that were supposed to be .030"-over).

If you have to overlap the ends to get them in the hole, send them back.

 

They didn't overlap at all, I have bout ~.040 gap. Could this be the problem? I cleaned up an old expansion ring and put it on a piston with new rails and the pistons went in great, so the problem seems to be with the summit(Hastings) expansion ring. Any ideas?

 

what brand of pistons are you using? did you follow that link with the rings and see the rings sticking out of the ring land like is shown? if so, its possible the lands aren't deep enough and thats exactly the problem. regardless of the ring gap, if the rings fit in the bore and don't overlap, its likely the first problem.

without seeing the parts first hand, its a tough thing to pinpoint.

 

The link you posted shows also shows exactly how to check for that condition, by the way. I think you should do the check they recommend and then you'll know. Like was said above, this is tough to do over the internet without the parts actually in-hand.

 

That condition does exist with my stock pistons. Is it ok to reuse the stock expansion ring or do I need to send these back?

 

If you don't want to wait for new parts, and the stock expanders are in good condition, and are EXACTLY the same height and design as the replacements, you should be able to reuse the expanders. Personally, I'd get replacements locally so I could continue the project, then send the entire set back with an explanatory note, requesting a full refund.

 

Did you have the engine overbored when you went to new pistons? 30-over vs. standard bore? If so, you can't use any of your old rings. They are matched to the bore diameter they are designed to fit.

 

No over bore, just a hone and rering. I just reused the old ones as this is a low buck rebuild, which explains all the summit racing brand parts. I already ran into another problem, but that looks like another thread...