[Healeys] Oil Pumps

richard mayor boyracer466 at gmail.com
Mon Dec 30 18:47:14 MST 2019

[image: DSCN4774.jpg]

100/6 rotor style oil pumps were an engineering disaster. While the design
itself is OK, the large physical size of the rotors in the pump creates a
lot of resistance and stress in other engine components. It puts great
pressure and increased wear on the oil pump driveshaft gear and the
camshaft great. This back pressure also results in the camshaft being
driven forward more forcefully into the camshaft thrust plate. It also
stretches the timing chain.

As this problem became apparent, Austin modified the camshaft thrust plate
with the addition of a circular oil groove.  When that was not sufficient
they changed the thrust plate to a bronze type of material with a circular
oil groove. Eventually they replaced the rotor style pump with the gear

I the photo I have attached, the plate on the left is the stock steel
thrust plate. The middle plate is a late 100/6 bronze style thrust plate.
The thrust plate on the right is the result of using a Denis Welch 100/6
"high volume" oil pump. The cam has ground itself into that thrust plate
about 1/8th inch.   Look closely at the oil pump driveshaft in the photo
and you will see that the gears have been sheared off. The gears on a very
expensive Denis Welsh camshaft are also sheared off.

Calling a 100/6 oil pump a "high volume" pump is like calling a prostitute
a "social worker". They both do the job but the consequences can be tragic.

My advice:  Do not use a 100/6 oil pump.  The gear style pumps are more
than adequate.  And, don't believe everything you read in the Denis Welch

If you insist on using the 100/6 oil pump then you should  get the
Torrington bearing camshaft thrust plate from Denis Welch as well.
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