[Healeys] oil pump

Bob Spidell bspidell at comcast.net
Tue Oct 30 18:54:59 MDT 2018 

Probably due to aeration (foaming) of the oil due to cavitation. When I 
was bringing my BJ8 home from my dad's after after installing a rebuilt 
engine, I cracked the pan on the concrete lip of his shop (but didn't 
realize I was leaking).  As I drove home, I saw the pressure at speed 
drop from 55psi to about 35psi and thought: "Hmmmm ... that's odd."  
Stopped on the driveway for just a couple minutes while I opened the 
garage door and when I pulled the car into the garage there was a small 
puddle on the driveway (mystery solved).   Welded the pan and added a 
couple quarts and drove it a couple hundred miles--at normal 
pressure--before replacing the pan.

The oil pressure gauge indicates both long-term trends (e.g. bearing 
wear) and short-term (oil loss).  If you had an oil temperature gauge 
you'd see the temp go up if you're losing oil, as the oil becomes less 
viscous.


On 10/30/2018 4:24 PM, Michael MacLean wrote:
> Well then please explain to me how a Bugeye I owned in 1971 would drop 
> from 60 PSI at speed to 40 PSI over a period of time.  When I checked 
> the oil it was a quart low.  Adding a quart, the "at speed" pressure 
> returned to 60 PSI.  I mean it was great to have a low oil indicator 
> like that, but I never understood how it worked.
> Mike MacLean
>
>
> On Tuesday, October 30, 2018 2:22 PM, Michael Salter 
> <michael.salter at gmail.com> wrote:
>
>
> 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 
> <mailto: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 <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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