Dirty Piston Grooves

[Psucamper]

During my GD case 2000cc buildup I see carbon in the piston grooves of a good
previously used P/L set. The deposits do not appear hard caked in the grooves and when carefully probed seem friable. The standard machinist warning "don't dig out the deposits with a broken ring" seems reasonable. What's a good solvent (if any) to get these deposits to go away without damage? Gumout?, lacquer thinner?. I am willing to let these pistons set in something for a long(ish) time if that's what is needed. Anyone else do this kind of stuff? Bob L.

[Amskeptic]

During my GD case 2000cc buildup I see carbon in the piston grooves of a good
previously used P/L set. The deposits do not appear hard caked in the grooves and when carefully probed seem friable. The standard machinist warning "don't dig out the deposits with a broken ring" seems reasonable. What's a good solvent (if any) to get these deposits to go away without damage? Gumout?, lacquer thinner?. I am willing to let these pistons set in something for a long(ish) time if that's what is needed. Anyone else do this kind of stuff? Bob L.

A Kustom-Toothbrush Handle with carb spray would be my first line of attack. New toothbrush handles won't work because they have soft grippy junk on them. The old hard plastic you can grind down to a facsimile of a piston ring profile to get into the edges of the ring grooves. The back sides of the grooves are not half so critical as the horizontal surfaces. That is where the sealing occurs. The back sides are where gas pressure is allowed to push the rings out against the cylinder walls.

What brand pistons/rings do you have? Re-using rings is a no-no once you have pulled the pistons out of the cylinders, Moly-impregnated Mahle rings will quickly be destroyed if you glaze-break the cylinder walls with our typical crude grit honing stones.
Colin

[Psucamper]

Colin...Thanks for the toothbrush cleaner idea. I'll try it. The new rings will be Grant cast iron. Used a 220 grit flex-hone to deglaze the cylinders. Surfaces look beautiful Ad astra per aspera! Bob.

[Gypsie]

I had good cleaning action using a strong piece of hemp string ( used kind of like dental floss). You can get a shoe shine motion going. a few knots make a "scrubber". Also a plastic scrubby (kitchen style) on its side will slip in there. Simple green, carb spray, whatever doesn't melt your scrubbers.

A thorough clean and blow dry after, of course.

[Psucamper]

Now that's a really inventive idea. I'll do it. Thanks. Bob.

[Gypsie]

Heres what it looked like for me:


Crazy enough to try it without pulling pistons: