> > Fred Vandeman wrote:
> > >
> > > As many/most of you with aircraft
instillations......I will
> > be supplying
> > > oil to the apex seals by putting 2cycle
into the fuel.
> > I'm finishing
> > > my 20B overhaul and will be closing the
front cover
> > tomorrow. Should
> > > I remove the drive gear and
shaft........or leave it
in?
> > If it were me I would take it out. No
telling what it would
> > do with no load.
> >
> > Paul Lamar
> The roll pin (red arrow in pix) squirts oil
onto the oil
pump chain. I
> was not sure if it would get enough lube
without it so I
left mine in. I
> took the gear off though, so the shaft no longer
rotates. If you remove
> the shaft, oil will just run out the end of the bore.
>
> Chuck Dunlap
Good point Chuck. Sorry I missed that.
Paul Lamar
I removed the gear/shaft asembly and threaded the shaft
(inside and out) for pipe plugs. Therefore, the shaft is
pressurized and the oil pump chain is still lubed thru the roll
pin hole.
Ken Powell
I'm replying via a web browser... So if this gets tacked onto the
front of the message instead of the end, my apologies.
I just pulled the gear and shaft for my oil injection pump, and
threaded the hole of the front cover oil supply gallery to
take a 6mm
setscrew. Seated in the oil gallery just fine, and used a little
lock-tite to keep it there.
Now the front cover of my 20B looks just like that of a 13B, and
there's no roll pin in it anywhere... just a hole. Looked
to me like
that's where the oil came out of the metering pump shaft
after doing
it's job. Guess I'll have to go back and look again. At least the
plug is reversable!
Tom Kendall
I am not so sure that lubes the chain. It might have that
effect but I think the hole is mainly for the roll pin which
I assume keeps the
shaft in place. If it were not for that roll pin the metering
pump gear could become disengaged from its drive gear upon
assemble. I
think there is plenty of oil coming out of the front main bearing
and splashing around in there to lube the chain.
Come to think of it I am sure of it as just to the right of
that roll pin is the vent for the oil reservoir for the
injection pump. That is vented to the near atmospheric
pressure in the front cover. Therefor no pressure ... no
squirt. We went around
and around about this quite some time ago.
Old message below.
Paul Lamar
**************************************************************
*********
From: Paul <rotaryeng@earthlink.net>
11/15/2000 22:36
Subject: oil injection pump
Somebody mentioned they thought the oil injection pump was
not a pump at all but just a metering device that relied on
engine oil pressure.
Not the case. The oil injection pump is indeed a pump and is
gravity fed with oil at atmospheric pressure. The pumping
action comes from the fact that the plunger moves up and down
in its bore as shown in this drawing from the Mazda book
called "Rotary Engine". The stroke of this up and down motion
hence the amount of oil injected is controlled by the
throttle opening linkage.
The mechanical pump is an off the shelf motor cycle part
bought out by Mazda. As I recall it is made by Mikuni.
Paul Lamar
Paul, you must have a different setup than my (13B 1986) which has no
reservoir or vent. The shaft will come out without removing the roll
pin. Maybe the only function of the roll pin is to reduce the pressure
available to the "pump" inlet. Maybe dumping the excess oil on the chain
is not needed. In that case, you could block off the oil passage back at
the front housing. I thought of doing that but I worried about lack of
lube on the chain.
Chuck Dunlap
I just took my shaft out.
You are right about the roll pin. It is shorter than shown in my
sketch. The oil reservoir is below the shaft.
I used a 12A cover to make that sketch. I can see from your
photo your front cover is different than the 12A front cover.
I don't see the bulge for the oil reservoir.
I still see what looks like a vent hole over near the wall
in your photo. Looks like it is cast in.
Perhaps the roll pin function is to limit the pressure
in the plain bearing for the oil metering shaft. Perhaps
it was easier and cheaper for Mazda to use a roll pin rather
than tap it and use a threaded plug.
The roll pin hole itself was necessary in the manufacturing process
to drill out the oil feed gallery below it.
Paul Lamar
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