END GAP ESCAPE PATH
I often feel that people will gap the top oil ring rail improperly. The top oil ring rail needs to have a gap that is the same as the 2nd (scraper) ring above it, at operating temp. Gapping it the same is a safe adjustment. The tapered second ring gap will open as the face seats, but close some at operating temp. This completes the path for any “pressure spike” to escape via the oil ring groove drain holes. If the top oil rail is tight, it will effectively have the same detrimental effect as having the scraper ring tighter than the top (compression) ring, upsetting the ring seal. A properly working ring package needs a controlled path for pressure spikes to escape, to prevent disrupting sealing. This is especially important with gas ported pistons or rings. Bonus tip, grind 3-4 at a time to increase stability and don’t have a lot of the fly end hanging out. This way they won’t grab the wheel and bend.
Ron Flood
Cedar Machine
North Branch, MN
September, 2022
