Tracy Crook wrote:

 A popular mod for flying rotaries is to install a spacer under the

oil

bypass valve to disable it.  The piston in the thermal pellet is

usually

removed when doing this.

Another popular mod is to install the Racing Beat under drive pulley

on

the

crank to slow down the waterpump and alternator.

If the spacer was made to fit the stock pulley before changing to

the

aftermarket pulley, the bypass valve will be in the incorrect

position

due

to differences in the pulley.  This results in low oil pressure,

similar

to

the blown out O-ring in the front cover.

This problem has shown up in at least three engines, Jerry Bass'

being

the

latest.  If you experience low oil pressure on a newly built engine,

check

this as a possibility.

Tracy Crook
tcrook@rotaryaviation.com
www.rotaryaviation.com

-Bill Hyde wrote:

Tracy, in your book you used a spacer 5/16 in. long. What would be the
proper length using the Racing Beat pulley?
Bill Hyde

If you did it the way I showed in the book, you will not have the problem.
I showed a tubular spacer that allowed the thermal pellet piston to remain
in place.  The piston would put the bypass valve in the correct spot when
the oil warmed up even if the spacer was a bit short.  I also think I sized
the spacer for use with the Racing Beat pulley to begin with.

When using the method developed by Bruce (removing the piston and using a
solid spacer) spacer length becomes critical.  In Jerry Bass' engine, it
resulted in the bypass valve leaving about a 3/32 x 3/16" hole exposed in
the eshaft bypass opening.  That's a lot of oil at 30 - 70 psi!

Tracy Crook
tcrook@rotaryaviation.com
www.rotaryaviation.com

 
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