Removed and disassembled the injection/metering pump today to determine
cause of oil leak.  There is a seal on the output adjustment shaft that was
compressed and hard (looked baked) and obviously not sealing (used pump from
Atkins).

One interesting note - the output adjustment (arm normally connected to the
throttle linkage) is not a proportional control; it is basically a two
position setting, low flow at low end (idle), and high flow for anything
just above idle position.  So in our application where we just tie it off,
the arm position is not critical, anything about 10-15 degrees or so off the
low stop is as high a flow setting as it is going to get.

Not able to determine the internal porting, but it does not appear to be
positive displacement to each of the 4 ports.

Al

(snip)
 the oil entrance is right behind the relieve hole on the other side of the
shaft bore, coming out of the cover wall.

Oil will leak out when the shaft is bad. Under normal condition, there can
be no pressure buildup in the pump, because it is all open to the crank case
via the oil inlet and relieve hole. BTW, the shaft has a flat section on its
running surface toward the pump for oil feed.

The actual pump does not have a drive plate. The picture shown on the ACRE
site has no resemblance with the physical design of the real pump. There are
even functional differences. The most significant functional difference is
that the piston makes two strokes per revolution.

Richard Sohn
N-2071U
unicorn@gdsys.net

-Al Gietzen wrote:

Just a further note on the metering pump; that seal for the adjustment shaft
is apparently hard to come by, so I found that two 1/16 x ¼ i.d. x 3/8 o.d.
O-rings side by side in the groove solved the problem just fine.

Also, as noted below, the position of the adjustment arm is not critical as
long as it is somewhere off the bottom end.  A nice way to anchor it is to
remove the arm, turn it over, place it back on the shaft and mark where it
hits the stop pin.  Then cut off the arm, notch it to fit the pin, and
reinstall it (still turned over from the original position, of course). See
attached photo.  It results in positioning the adjustment about half way
between the stops.

Al

While  we are on the subject Richard had one disassembled at Rotary Roundup.
Here is one of Al's pictures and one of mine showing the pump disassembled.

BTW I don't recommend this 2 rotor 13B pump for use on a three rotor. Not enough apex seal 
cooling and lube oil for all three rotors.

Paul Lamar

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