TOTAL SEAL RING GAPS AND GAPLESS THEORY
TOP RINGS
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Conventional top rings with conventional second rings should be
about .012�. (.0035� per inch).
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Conventional top with Gapless 2nd ring sets should be around
.020�. This wider gap is needed because pressure builds up between
conventional top and gapless 2nd on the power stroke. This pressure needs to
vent after BDC of the power stroke or it will unseal the top ring in the next
cycle.
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Gapless top rings heat up more than conventional and requires
about .020" end gap to allow for expansion
SECOND RINGS.
- Conventional second rings should be about .012
(.0035� per inch).
- Gapless second rings need more end gap just like
the top gapless.
OIL RINGS
- Both rails should be .020� or more.
GAPLESS TOP VS. GAPLESS SECOND
- Gapless top rings make more power than gapless
second rings. The shape of the top ring is designed strictly for
compression and leakage is an absolute minimum. The second ring is shaped
for scraping excess oil from the cylinder wall and this compromises the
ability to seal compression.
- Gapless top ring sets make power all the way up to
infinity. Second gapless rings perform nicely up to 7850rpm. Above that
they still work, but the residual pressure from the power stroke begins to
disturb the sealing of the top ring after TDC of the overlap. After 7850
this pressure between second and top ring does not completely bleed off
during the exhaust stroke. This residual pressure carries over into the
beginning of the intake stroke and progressively interferes with the top
ring seating as RPM increases. You will notice that the top ring has a
generous gap in a second gapless ring set. The purpose of this is to assist
pressure bleed off during the exhaust stroke.
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(770) 457-2532 (Atlanta area)
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