[Healeys] oil pump

Michael Salter michael.salter at gmail.com
Tue Oct 30 10:49:54 MDT 2018


Yes, absolutely true Bob.
Decreasing oil pressure can certainly be an indicator of increasing
clearances.

M

On Tue, Oct 30, 2018 at 12:22 PM Bob Spidell <bspidell at comcast.net> wrote:

> re: "... delivery pressure itself is not that important and is really just
> an indicator that oil is being delivered to the bearings ..."
>
> Pressure is useful as a trend indicator.
>
> On 10/30/2018 8:54 AM, Michael Salter wrote:
>
> I have a book "Repco Engine Service Manual" produced by Repco of
> Repco-Brabham fame that I use as my bible for engine building.
> On the subject of oil pressure it states that delivery pressure itself is
> not that important and is really just an indicator that oil is being
> delivered to the bearings.
> Of much greater importance is "thin film pressure" which is generated by
> the engine forces on a bearing which can be as high as 8000 p.s.i. at high
> RPM and is determined by the oil type and temperature, and the engine
> design.
> Based upon this I believe that concentrating on having good oil pressure
> at idle is wasted effort. What is important is that the engine has some
> pressure at idle but good pressure in the normal operating range.
> A pump which puts out a huge volume uses excessive horsepower and can
> result in accelerated wear of the pump drive.
>
> M
>
>
> On Tue, Oct 30, 2018 at 11:30 AM Bob Spidell <bspidell at comcast.net> wrote:
>
>> I'll offer what I know/have heard*.  I have the 'high capacity' type in
>> my BJ8, which is what the DWR techs/sales people recommended for a road
>> car.  Older 6-cyl cars had a rotor type pump.  They (the rotor type) are
>> supposed to be more efficient--i.e. they pump more oil--at lower RPMs.  At
>> some point it was discovered, probably from service bay repairs, that this
>> type of pump put an excessive shear load on the bevel gears on the cam that
>> drive the pump, causing them to wear out.  Later cars started getting the
>> gear type pump, which is less efficient at lower RPMs but puts less of a
>> load on the cam, and is probably less expensive to manufacture as well
>> (esp. if the gears are the sintered iron variety).  I think the bevel gears
>> on the cams were re-engineered, IIRC they got an additional tooth to spread
>> the load.
>>
>> The Welch HC pump is the rotor type.  I did a full engine rebuild and
>> installed the DWR HC pump; I didn't notice any pressure change worth
>> mentioning--I 'gained' 15 PSI at idle when I had my gauge overhauled--but
>> the 'high capacity' I believe refers to volume rather than pressure (which,
>> of course, is mostly dictated by engine speed).   The 'standard type' pump
>> is a gear type, hence it's more appropriate for high-RPM race engines as
>> pump flow is proportional to RPM, and at 6K RPM or more you'll get plenty
>> of oil with less load from the gear type.
>>
>> I'm not positive, but if you look at the photos closely, you can see the
>> 'gallery plug' on the top of the case.  I suppose it allows inspection of
>> the innards of the pump without having to break the case.  I believe it's
>> threaded so not likely to pop out.  If you're getting a new pump you'll
>> likely need a new drive shaft and, surprisingly, DWR sells it cheaper than
>> our (US) vendors sell it at (I think they might import the DWR shaft).
>> * apply appropriate grains of salt
>>
>> Bob
>>
>> On 10/30/2018 5:12 AM, simon.lachlan at alexarevel.plus.com wrote:
>>
>> Hi,
>>
>> Has anyone got the Denis Welch oil pump ENG672M? See:-
>>
>>
>> https://www.bighealey.co.uk/performance-parts/austin-healey/engines/3000-bottom-end?page=3
>> Their text:- “Heat treated castings for longer life and removable
>> gallery plugs to be sure it is clean are advantages of both types of oil
>> pumps we offer. We recommend the high capacity for all road engines using a
>> standard type crank up to 6000 rpm and the standard pump for race engines,
>> steel cranks or anything over 6000 rpm. Both are precision machined and
>> assembled in-house to control the highest quality.
>> - ENG672 is the standard type.
>> - ENG672M is the high capacity pump.”
>>
>> What are “removable gallery plugs”?
>>
>> Is it just me or is the above a bit counter-intuitive? “High capacity”
>> for road cars and “standard” for race engines? Surely the highest capacity
>> is needed where the engine is working hardest ie racing?
>>
>> And don’t I remember that, with the standard BMC pumps, the older type is
>> reckoned to be better than the newer type? Is this something similar to
>> Denis Welch’s two pumps?
>>
>> Anyhow, if anyone’s got one…..what’s it like? Did the oil pressure
>> improve at all?
>>
>> I’m guessing that most people will have fitted one as part of a big
>> rebuild thus they won’t have straightforward “before and after”
>> comparisons. I’m thinking of fitting mine to my engine as part of a small
>> winter project and hope I can squeeze a few more psi into the system.
>>
>> Thanks,
>>
>> Simon
>>
>>
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