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
Subject: [FlyRotary]
Re: OIL METERING PUMP
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
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.
----- Original Message -----
Sent: Monday,
October 04, 2004 7:05 PM
Subject: [FlyRotary]
Re: OIL METERING PUMP
Subject:
[FlyRotary] OIL METERING PUMP
Richard;
Thanks
for input on this. That relieve hole looks very large and not likely to
blocked, especially on a newly rebuilt engine. Or am I looking at the wrong
thing; how does the oil get into the recess?
Oil
entering the pump can leak past the adjuster shaft if the seal was bad, right?
And what happens to the oil that enters the piston with the blocked exit port
as the piston moves to eject the oil? I was thinking it gets forced back
past the piston into the drive area where it can then leak past the adjuster
shaft, but I guess the feed oil is in that area anyway. Still; it seems
forcing the piston against the oil with no exit port would put high stress on
the drive plate, no?
Al
Al,
here is some more info on the OMP
oil feed.
Oil is coming into a recess in the
pump drive shaft. The thus formed cavity has a relieve hole as shown in the
pic, making the pressure in the cavity practically even with the crank case
pressure, depending someway on the flow rate. The roll pin in the relieve hole
is to make sure there is no air pocket in the cavity, which is connected to
the pump intake.
Each out put is driven by a
separate piston and two are together
per stroke. Each stroke is small enough not to create
a problem when you block a line off. It Would not hurt the pump if two
outputs are connected for double oil flow.
I hope it is clear, and not confusing.