Pinched ring land?

[mixbreed]

I lost some compression on one cylinder it went to about 50%. After pulling it down everything looks really good. It does appear that the top ring land might be pinched some. It's kinda hard to push the ring around on the piston. What generally makes this happen?

It's a conventional headed BBC with 450hp on nitrous on a fogger. The pistons have a ring pack that's .450" lower than the top of the piston, gas porting, and a heat dissipating ring between the first and second ring. I use Torco 118 fuel.

Thanks,
Kevin

[steve hurt]

Generally it is DETONATION that pinches the ring......


just curious, how many runs did you get on your bullet and what kind of rings do you run?

thanks

steve

[mixbreed]

About 12 runs total, maybe 8 nitrous runs. Along with about 30 dyno pulls.

Childs and Albert rings

Thanks,
Kevin

[Monty Mikho]

Check the piston with a different ring from another piston that its not tight on. C&A? Im guessing tool steel rings? If so throw them sucker in the garbage. I had the same problems with them and it ended up being the rings being crowned..