Fred Vandeman wrote:

Have my 20B in pieces for overhaul and would be quite easy to enlarge
the trailing plug hole.  So far it seems that the potential advantages
of this mod can be argued back and forth but the only potential downside
that I have heard is possibly some increased blowby......and it would
seem probable that this is not a problem.   Are there really any
practical negatives to enlarging the plug hole?  True, it may not
help.......but will it hurt?

Fred Vandeman
Velocity XLFG

It could hurt starting. There is a pressure difference when the apex
seal crosses that hole so if the hole is bigger the leak is greater.
Probably not noticeably at high RPM because the rotary is reputed
to run at high RPM without apex seals.

Paul Lamar
 
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