Having some experience with Detroit racing iron here's my beliefs/observations.
The Teflon buttons are a trick used with full floating wrist pins to keep them
in position in the piston. You can cut grooves in the ends of the pin bores and
use snap rings, but a failure to retain the snap ring in the groove is quick
death to a cylinder wall.
The missing ring is indeed to reduce friction. This allows more horsepower to
be made if you compensate for the loss of the ring. To compensate for the
missing second compression ring the top ring is fitted with the absolute minimum
end-gap possible to eliminate blow-by, or a special gapless top ring. If you
set the end gap too tightly you wind up with the problem you found- a severely
broken ring. And of course as soon as the ring begins to wear the gap opens and
the horsepower starts to fall off.
I've seen engines set up this way with pieces of rings scattered through many
of the bores. It seems this setup is usually used in combination with higher
compression ratios. Too low octane fuel and resulting pre-ignition breaks the
top land of the piston and lets the ring escape into the cylinder. During high
rpm valve overlap (both valves open) the pieces escape into the intake manifold
and find their way into "healthy" cylinders as well trashing the pistons,
valves,and sometimes the head(s). All this trouble was for a motor that was
only driven a quarter mile at a time. :-)
Remember, when modifying for performance: If some is good, more is better,
and too much is just right!
Clay_Scott@HP-Loveland-om10.om.hp.com
______________________________ Reply Separator _________________________________
Subject: Re: "No more 'ring around the piston' "?
Author: Non-HP-triumphs-owner (triumphs-owner@triumph.cs.utah.edu) at
HP-Boise,unix2
Date: 7/21/95 10:23 AM
On Fri, 21 Jul 1995, Andrew Mace wrote:
> Only one thing was strange: I have yet to find any evidence of the middle
> ring! And this brings me to my only real question at this point. Does anyone
> have any good ideas as to 1. where the middle ring went or 2. why it would
> not have been used when the engine was last assembled (long before we got the
> Fellow Scions, I humbly ask your advice, speculation, WAGs, learned
> treatises, etc.
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