Date: Sat, 1 Feb 1997 01:02:39 -0800
From: Mike West <mwest@CDSNET.NET>
Subject: Full-flow oil pump

  My posts and the replies to questions are slow the last few day.

 I have sundry snakes to kill and wolves to drive away from the door.

 I'll get the questions answered prob'ly this weekend.

 I finally got to do some work on my engine tonite.

 I'm working on the full-flow pump setup.

 The case was all spiffed up some time back and the ports chamfered
to eliminate the sharp edges which are pressure drops.

 I thought I was done with the pump after a mild chamfer around the
inlet of said pump.  Not to be.

 First, this is an older case with 8mm oil galleys and a single relief.

 The pump has 21mm gears (length) and an 10mm outlet.

 So when I set it up for an external outlet, I have to plug the regular
outlet and put on the new external outlet plate.

 The hole in the pump housing outlet was about 10mm so I ran a 1/4
NPT tap in the sucker and rounded up a plug.

It turned out to be perfect. The plug will go in just far enough to
fill the inside area where I would have another pressure drop if I didn't
fill that outlet well.

 I got one of the cheap aluminum plates. I don't recommend them but the Berg
cast steel job is some $50. Mine is the $10 job.

 The plate has a bad plating job and isn't even flat on the gear side.

 So . . .  I wanted to see where this outlet on the plate lined up
with the pump housing. Like, is there good clearance for the oil to
flow.

 I made a paper template of the mounting holes and outlet hole and
then cut the holes out with a razor blade.

 This, I then lay over the pump housing.

 About 1/3 of the outlet hole in the plate was covered by the housing.

 I marked the offending metal on the housing with a pencil and got out
the rotary burr I had used for porting the heads.

 By the time I got the radius cut in there to the bottom, it just matched
the pipe plug and gives me a clean continuous line of flow
out the outlet.

 Caution is the word, any nick you might get on one of those walls
where the gears turn, would be a leak.

 Right now I'm working the gear-side of the cover plate down on a mirror and
a piece of emory cloth. The mirror is my surface plate.

 A surface plate for the novices, is a flat, flat plate that you can
make something else flat with.

 Put the emory cloth on the plate with the grit up, put the part you
want to make flat on that and start pushing it back and forth on the
emory cloth, then rotate the part 45 degrees and back and forth some
more and rotate and . . . .   It's another form of "lapping"

 I guarantee you if you use one of these cheap cover plates, you will
need to do this or you will have very poor pump output.

 Once I get this flat and have checked that the gears themselves are
not more than .001" below the surface of the pump housing, I will use
it "as is" for a while.

 Added note: if the gears are not within that .001", I will "lap" the
surface of the housing till they are where they should be.

 It is some "die-cast" aluminum and too soft to last long.

 A better setup, besides the cast steel one, will be to get a piece of
1/16" X 3" square tool steel and drill it for the mounting and outlet
holes and bond it on the die cast part on the gear side.

 This tool steel flat stock is readily available in the big city at
a machine supply house. 18 inches long by 3inch is about $12.

 So I would still be in for only $22 bucks plus my labor.

 If I had six of them to build it would only be $2 more per plate.

 Still beats the $50 job.

 west     be on the road in no time?   :-)