Scions:
Just put together my TC's head last night and, as I always do at this
point, wondered about the utility of the little o-rings that go under the
valve stem keepers. Now that I have someone to ask, I'll do so: How could
they do any good?
I understand the theory - they prevent oil running across the rocker arm
and directly down the stem where some of it, aided by the intake vacuum,
could find its way between the stem and the guide and get into the
combustion chamber. But, as anyone who has removed the oil filler cap from
an idling engine can tell you, there is oil flying all over in there. I
can imagine it what it must be like at 3000 rpm and 60 psi oil pressure,
but dare not look. In this environment, it intutitively seems that there
would already be so much oil on the valve stems that the guides would have
to be severely worn before the presence of any additional oil affected the
amount that gets burned.
Has anyone ever (inadvertently, I suppose) tested this by leaving the seals
out? My guess is that with a reasonably good stem/guide fit, there would
be no effect. Of course, even with new guides and valves, I put the things
in, as always. Erring on the side of the gods, I guess, and, if nothing
else, they do help to hold the keepers in until the valve-spring compressor
is released.
Russ Wilson
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