Sorry,
But how can you influance oil pressure at idle by tinkering with the
spring
pressure of the relief valve.
IMHO you can up the oilpressure at idle by diminishing the clearances of
big-end and main bearings or by making certain oil galleries a smaller
bore.
The only purpose of upping the spring tension of the relief valve
is to make oil pressure higher at higher revs.
Or do I miss something here?
Lex.
Holland.
-----Oorspronkelijk bericht-----
Van: Paul.Kile@Aerojet.com [mailto:Paul.Kile@Aerojet.com]
Verzonden: vrijdag 18 februari 2000 18:40
Aan: 'Susan and John Roper'; Rich Atherton
CC: buick-rover-v8@autox.team.net
Onderwerp: Motor oil
Rover motors have been very reliable with low oil pressure at idle, but
MG
saw fit to uprate the oil pressure relief valve spring to give about
15-20
PSI at idle when they built the MGB-GT V-8. The reason here was
probably
more for owner piece of mind than for engine longevity. MG owners who
were
used to looking at 4-cylinder engine oil pressures would have been
horrified
to see their pressure drop off to <10 PSI at idle! Most GT V-8s were
also
equipped with a 0-60 PSI oil pressure gauge instead of the 0-100 PSI one
used in the 4-cylinder cars, again to allow the needle to swing over to
a
position on the gauge that people were used to seeing and were
comfortable
with.
Remember that the V-8 engines were originally designed for cars that had
no
oil pressure gauges, only idiot lights. And if you set your idiot light
to
turn off at 4-5 PSI, you would never see a problem. I think if you
start
looking at nominal oil pressure values for most American V-8s, you will
see
a similar pattern to the Rover motor.
Cheers,
Paul Kile
1974 Factory MGB-GT V-8
-----Original Message-----
From: Susan and John Roper [mailto:vscjohn@huntnet.net]
Sent: Friday, February 18, 2000 9:03 AM
To: Rich Atherton
Cc: buick-rover-v8@autox.team.net
Subject: Re: Motor oil
Rich, "This guy" that I cited, Smokey Yunick, is one of if not the most
respected race car designer/builder ever with one hell of a portfolio
when
it
comes to building engines that perform and live. I personally have run
a
Rover
engined race car for 5+ seasons with 10# of pressure at idle and no
bottom
end
failures, and know others who have run with less, same result. Perhaps
you
should measure the oil pressure on production Rover V8s, which also run
many
miles with a reputation for solid bottom ends. You will find that they
make
about 40# at maximum pressure and very little at idle. This is not a
subject
for guesses and old wives tales. There is solid data available. As for
the
drive gear, no one has "improved on it" as you suggest, and if it fails
in
service the results can be very expensive. The problem with the gear is
not
material, but the size of the drive and the power that some have
attempted
to
transmit through it. You might want to look at the Rover motors from 94
to
date
and notice that the front cover remains much the same, but that Rover
has
seen
fit to replace the oil pump with a design driven directly off of the
crank.
I
guess they just could not figure how to "improve" the original design.
I
would
be most interested in any configuration that you have come up with that
will
give 30-40# at idle and only 70 at full pressure and operating temp. In
my
experience that is not possible. John
Rich Atherton wrote:
> So you are saying that you would Want this guys idea of 10 psi per
1,000
> rpm? No thank you ! Please.!. I do NOT want my engine to be idling
with
> only 8 psi of presure...That's a HUGE indication something is broken
or
> severely worn. NOPE Gimee 30 -40 at idle, and 60 -70 at anything
over
> 1,800 or so, and I'm very happy. I will gladly give what little
horsepower
> that hivol pump will draw compared to the benifits of have plenty of
oil
> when and where I want it..
>
> As for the drive gear, as I remember, it's easily replaced at the
bottom
> of the distributor, and yes it was a weak area, but as in all things,
it
can
> be improved upon. Porpoer cam cutting of the drive gear, and using
bronze
> driven gear....although as I remember reading somewhere, the broze may
wear
> far too quickly...the driving of the pump shaft is where I remember
the
> problem being. It's been a while but as I remember it's a pin that
drives
> that pump shaft...this can be changed. there is nothing that can't be
> improved upon..
>
> Rich
>
> ----- Original Message -----
> From: Susan and John Roper <vscjohn@huntnet.net>
> To: Rich Atherton <gumby@connectexpress.com>
> Cc: <buick-rover-v8@autox.team.net>
> Sent: Thursday, February 17, 2000 9:43 AM
> Subject: Re: Motor oil
>
> >
> >
> > Rich Atherton wrote:
> >
> > > Most of the posts on this subject have missed a serious
concern.
> One of
> > > the weaknesses of the Buick/Rover motor is the oil pump drive.
the
gear
> on
> > > the end of the dizzy that drives both the pump and ignition has
limited
> > > capability. Any increase in pressure by viscosity or increased
spring
> > > pressure on the valve increases the load on that gear. Excessive
oil
> pressure
> > > not only unnecessarily loads the weak gear but also soaks up
horsepower.
> > > Smokey Yunicks's rule of thumb is 10# per 1000 rpm. Me, I trust
Smokey.
> John
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