Broke a ring? To help prevent this from happening, don’t use a ring compressor on pistons with aligning pins for the rings in them. It is next to impossible to get all of the rings lined up correctly before tightening the compressor. Instead, install them one at a time, starting with the bottom ring and working your way up. Once the piston with the bottom ring is in the cylinder, the next ring can be installed on the piston and so on. Usually the rings can be squeezed down enough with your fingers to get them in the bore as there should be a small taper at the top of the cylinders to help them compress enough to slide in. A small pin punch or something similar can also be used to push in any high spots your fingers can’t. Keeping everything flooded with TCW III oil helps to.
The current P/N for 5.5-6 horse std. size rings is 378432 (778344) and 378437 for +0.020 rings and they are gapped at 0.005 to 0.015. I try for 0.007 which is slightly above the lower limit. The gap should be checked at the top, middle and at the end of their travel below the ports. The gaps will probably be different at all three locations so use the tightest area in the cylinder to set the gap.
In the past, I’ve notice new OMC-BRP rings don’t need any filing as they are made so well to specs. However, a bunch of old Perfect Circle rings I have need the gap set everytime I install them, which is kind of nice as I can set them to what I want.
