[Healeys] oil pump

Bob Spidell bspidell at comcast.net
Tue Oct 30 10:21:54 MDT 2018

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 
> <mailto: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
>     <mailto: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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