Guess you guys know this but my factory pistons have a very narrow oil control ring(found this out after a couple of hrs trying to get the piston in thinking it was my worn compressor). I replaced one of my factory pistons(cast) with a fed mogul that the machine shop bal to match(same deck hieght). I put that one in first try,no prob then moving on to the old pistons I could not get the oil ring to go in the block!!! I checked for chamfered edge,,check,look for damaged ring,check,,look for trash behind ring,check,I take a look at an old oil control ring(fortunately haven't thrown all the junk parts away) and see it's about 1/8 in narrower than the new rings!!!!!!! I have built about 10-12 motors (far enough apart to forget most in between and usually diff makes/CIs so I'm not an expert but thought I knew the basics) and I've never run into this before. Is nothing standard??? I checked the hieght, never thought about the depth. Fortunately I can usually boat in Oct. so I may see the water some this year

COOL TOYS
I think you are talking about the new design low restriction oil rings.
Piston goes in nicely until the oil ring gets there.
If you ram it you feel you may break it.
I think they do make a cone type ring compressor made for the size diameter of your piston.
It fits into the cylinder just below the champfer in the block.
Requires a steady push, one shot to get them, if you tap tap tap they want to hang up.
Post what your solution was.
Good Luck
Brian

The depth of my factory piston grove is too narrow for the ring. The oil rings look normal to me just twice as wide as the stock ones.

You probably have a late model piston with a metric ring package and the piston you replaced is the older style with a 5/64 5/64 3/16 ring package if im correct one of your compression rings will also have excessive ring to groove clearance. All you need to do in this case is get the right ring set from fed mogul from your local parts supplier.Feel free to give me a call if you cant get fixed up Laz Mesa 1-305-884-5368

Thanks. I'm going to NAPA in the AM.