I'm getting old!! Here's a group of racers who have never seen the inside
of a stock flathead V8....well most of them had 4 ring pistons.
Todd, are you messing with an old flathead? Anyway, I wish I was more of an
engine builder; so any of you guys who understand this stuff better then me
please sound off.
I believe the 4th ring provides more of a stabilizing function and oil
metering to the piston skirt than oil control.
Here's a specific experience I had in 1957 with my first car, a 48 ford that
I bought with a tired 3/4 race motor. When it finally needed replacing I
bought a good 59AB from a junk yard and put in new rings and bearings just
to be safe. Ran great; but burned a quart of oil every 20 miles. I mean
this thing was like the township's mosquito control truck. When I finally
realized that the answer to the problem had nothing to do with breaking the
motor in I took it apart and discovered that the new 46-48 engine had 8BA
(49-51) pistons in it. The top oil ring groove in the 8BA wanted a self
supporting oil ring because the bottom of the third groove was open part way
around. The replacement rings I bought were for the 46-48 engine oil groove
with its solid bottom with small drain holes. So the top oil ring wasn't
working at all. And the oil ring in the 4th groove below the wrist pin sure
didn't do much for oil control.
Ed Weldon
----- Original Message -----
From: "todd" <todd@twinjugs.com>
Subject: 4 ring piston knowledge(NON LSR)
> Any chance someone here has dealt with 4-ring 4-stroke pistons?
> This would be two compression rings and two oil rings, one of the oil
rings
> in the normal position(between the second ring and the wristpin), and one
of
> the oil rings below the wrist pin(at the very bottom of the skirt).
> They are all one piece rings except for one of the oil rings which is a 2
> piece ring(consisting of an outer scraper and inner spiral wound expander
> spring).
> Todd
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