"Brian D. Cain" wrote:

While we've been on the subject of general engine reliability lately
(especially
with the o-ring thread a week or two back), I've been thinking alot about
the
corner seal rubber insert "problem".  Just three weeks back when I was in
sunny Lancaster, CA rebuilding a 4-port 13BT for a comrade of mine, I
noticed
yet again that the rubber inserts on all 12 corner seals were turned into
mush.

None of them were "rubbery" anymore but were vulcanized presumably from
ages and ages of engine heat.  Most of them had also lost their shape and/or
chunks of themselves into engine heaven.  My biggest guess at a resulting
problem here would be intake charge blow-by albeit probably not significant.
I've tossed the idea around of using solid corner seals before but I fear
that they
may be more detrimental than good per the assumed added friction on the
iron facings.

In short, has anyone experimented with this or come up with more reliable
alternatives such as inserts made of a higher heat resistant material?
What do you aircraft guys usually do for these?  Tracy, on your 800+ hour
GXL
engine, have you opened it up to inspect these corner seal inserts to see
what a
constant 5000rpm can do to them over time?

Thanks.

B

I assume you mean the little cylindrical pieces with a slot
in them for the apex seal ends. I was unaware that they had
rubber in them. Must be a third gen feature. Here is an illustration
out of the third gen shop manual.

If so you should try a set made from solid teflon Brian.
I suspect you would not be able to notice any reduction
in HP due to increased (if any) leakage. It is probably
mostly a smog thing at idle.

Paul Lamar
 
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