[Healeys] Oil pressure in a BJ8

[richard mayor]

Chris,

I hate to be negative about your good oil pressure but I fear you may have
a problem.  I am assuming that you have the "high pressure" oil pump from
DW.

Based upon that assumption, I can tell you that it is the rotary style of
pump that was used on the 100-6 engines. There were many problems with this
pump.  It has a very large capacity and as such it results in a lot of
friction, or back pressure in the system. Namely, it put stress on the
camshaft gear, the driving spindle gear, the timing chain and the camshaft
thrust plate.  This was a common problem with the early 100-6 motors.  One
fix was to machine an oil grove in one side of the the trust plate. Then an
oil groove on both sides. Then a bronze thrust plate with oil grooves.
Timing chains stretched.  Cam and driving spindle gears received excessive
wear.  That is why the switch was made to the gear style pump.

The rotary style of pump is actually a very good design. Nissan used it in
the Z car motors but it was 2/3rd the size of the Healey pump so there was
much less back pressure.

Many of us racers have used the DW "high pressure" oil pumps and discovered
that at some point, all of the teeth on the cam and driving spindles have
been ground off to such an extent that we have lost all oil pressure.  On a
shelf with my "offerings to the god of speed" I have a camshaft thrust
plate that has a groove that has been ground into it almost  1/8th of an
inch from the resistance of the oil pump forcing the camshaft into the
trust plate. I am sad to admit that it took me the loss of 2 race motors to
finally grasp why this was happening and before I switched back to the 3000
gear style pump .

Jeff Jonk did an excellent article about these pumps and the damage they
cause in the Healey Marque publication about 10 years ago.

Richard

On Tue, Aug 30, 2016 at 3:53 AM, Chris Dimmock <austin.healey at gmail.com>
wrote:

> Hi all,
> Recently someone asked about oil pressures, and the oil being used.
>
> My BJ8 engine was totally rebuilt in 1998.
> Today, my wife and I went for a drive up the M1 motorway and I kept an eye
> on oil pressure. Water temp was 185 degrees all the time. Air temp was ~22
> degrees Celcius.
> Lovely day for a drive to the Hunter Valley!
>
> Hot idle. After 70 minutes at ~70 mph, idle @ 850 - 900rpm = 40 lbs.
> Oil pressure at 2,000 rpm hot driving = 50 lbs
> 3,000 - 5,000 rpm hot oil pressure = 60 lbs.
> My wife said we wouldn't make our 3rd wedding anniversary if I pulled
> 6,000 in overdrive top..... ;-)
> Denis Welch oil pump.
> Fresh Penrite HPR 40 oil and filter last weekend.
> Draw your own conclusions. Mine are:
> the thermostat is perfect, and
> so is the oil pressure relief valve.
> Best
> Chris
>
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