"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

Huuummm-
I have taken apart and rebuilt a few engines and those 'plastic' inserts
were always there in the high mileage rotaries I did (almost all in one
piece). They were kind of stiff compared to new ones (always replace
that insert). AND use the FD flat springs under them instead of the wire
spring if doing engines before the FD version.
[Marc Wiese]

 
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