[Healeys] Oil Pump

richard mayor mayorrichard at hotmail.com
Wed Mar 5 19:01:19 MST 2014


Jonas,

The vane style oil pump was"original" only to the 100-6 motors. The change
over to the gear style pump came with the 3000's. The rotary vane style pump
puts out a greater volume but the down side is that it puts a lot of back
pressure on the driving spindle and the teeth on the camshaft, which forces
the camshaft forward into the thrust plate.  This was a problem with the
100-6's. Austin tried a couple of fixes. One, they tried a spiral oil groove
in the thrust plate. Two, they tried using a bronze thrust plate. Neither was
satisfactory.

Racers that have used the rotary "high volume" pumps from DW, that are
essentially 100-6 oil pumps, have had disastrous results for the reasons
stated above.  As an aside, did you notice that DW also sells those camshaft
thrust plates that have those needle bearings (forget the name right now)  but
there is no tie-in to the claim that the high volume oil pump is good up to
6000 RPM.

While the rotary vane style is a good design, the actual pump itself was just
too big for the application. In comparison, the 1970's - 80's Datsuns (Nissan
engine) Z cars used exactly the same rotary vane style but the pump is about
2/3rd the size of our Healey pump.

40 psi running and 20 psi idle is great.  Why is the owner complaining?  10
psi for every 1000 rpm is fantastic...and that's for a very expensive race
motor.

If you do replace the pump, and you buy one of those "County" brand pumps, be
sure to ignore that piece of paper with the dire warning to not open up the
pump as you may miss-align the precision alignment of the gears. Because, as
you may find, as I did when I decided to try a County pump a few years ago,
that the casting was so bad there was a large void inside the pump body where
the gears turned, that your new County pump would be worse than a pump that
came out of a blown-up engine that had sent all kinds of metal debris through
the pump that destroyed the gears.  I'm not exaggerating.

Richard

> From: jpaynepbr at cox.net
> To: healeys at autox.team.net
> Date: Wed, 5 Mar 2014 11:51:07 -0800
> Subject: [Healeys] Oil Pump
>
> We are rebuilding the engine from a '61 AH 3000.
>
>
>
> While the tolerances on the old pump check out (per my machinist) , the
> owner of the car was complaining of low oil pressure (40 psi running, 20
PSI
> at idle).  There was nothing on the top or bottom end suggested major
> problems to the main or rod bearings nor the typical rockershaft issues.
>
>
>
> Effectively, the cam and lifters failed and the valves and guides were shot
> on the motor.
>
>
>
> All of that said, there are some options for the oil pump as follows:
>
>
>
> Replace with new gear type - readily available.
>
> Replace with original style vane type - on backorder with all known
> suppliers with no delivery date in site.
>
> Re-use the old pump as is
>
> Obtain a re-built pump (I have no idea where I'd have this done)
>
>
>
> I was told that the gear type makes pressure at high rpm and the vane style
> at low rpm - if this is true, given this owner's driving style, I'm not
sure
> that a high rpm pump is the best way to go.
>
>
>
> Jonas Payne
>
> PBR Consulting Services, LLC
>
> 702.882.6711
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