> > > Paul Lamar
 > >
 > >
 > > > perhaps a toothed belt drive system would be better. It requires less
 > belt
 > > > tension.
 > > >
 > > > smale@ncinternet.net

I have never had such a failure, and have never seen one until this dreadful
picture came up. On one hand the shape is not ideal, and it could succumb to
an overtightened belt. On the other hand, they don't fail in street service
with the fan flange bolted on over the front. If high RPM was a problem, I
should have a box full of failed pulleys. I don't. I did not pass up the
chance to use all 8 bolt holes. Notice that some pumps have only 4 holes as
well as some pulleys. If so, just add the holes. If there is any discomfort
left at all, add a thick plate over the front of the center section. The
failed pulley looks as though the fasteners came loose first. This would do
in any installation. Also the plastic nature of the material just begs for a
cover plate and 8 bolts.

On another front: My friend (A mechanical engineer) went racing at Gingerman
last weekend and hosed 2 new motors. He used the 2 MM rotors with the 3 piece
seals against everyone's instruction. In one it just flaked off a small piece
of seal and blew it out the exhaust without damage to the engine, other than
lost power. On the second engine, a rotor and rotor housing are gone. Stan
the engine man said the three piece apex seals are no good for real high RPM.
Obviously. He says if you want that higher compression rotor, to mill the
slots to 3 MM and use the stock two piece seals. This is just a problem above
9,000 rpm so don't have a cow about the data. Just don't go there.

If you run one without a prop, and no rev limiter, keep in mind that they can
get to 9,000 with a quick throttle blip. The flex plate is not much mass. A
guy asked me one day what was the terrible sound his engine made when he
revved it up in neutral.
It was the rev limiter on his MSD. He had carbon seals so it was not hurt at
all.

I got mine running today. I had a dental deal going today and took the whole
day off.
The new oil sump tank seems to work OK. I left the breather line off for a
few seconds and blew oil all over everything. The breather hose flows the
wrong way around. The scavenge pumps pull so much volume that it has to pull
it from the top of the tank or the excess gas volume comes out the top of the
tank where the breather hose is ported. Except for that, it runs fine. Starts
instantly with 6 years on the rotor housings.

Lynn E. Hanover

 
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