declined the expense. I made a modification which seems to be
satisfactory. First I placed a washer between the spring and ball to
increase the blow off pressure by effectively lengthening the spring.
This raised it to C90lbs hot which worried me.
I then employed a method we used on the Cosworth pumps we used in
Formula Ford. I tapped a hole on the brass cover retaining the spring
and inserted a 6mm bolt and locknut which can be adjusted in to move a
platform the spring rests on to increase tension & pressure. This works
well, I think it is still set a bit high - 70-80lbs, possibly ok for
summer. No signs of a leak, Reason I used metric was I had a nut which
had a broad circular base larger in diameter than the hexs which I'm
sure seals it up nicely.
I believe no matter what you do to the spring the pressure at idle will
be unaffected.
Gos Cory
TC 5202, TF 5783
-----Original Message-----
From: mg-tabc@yahoogroups.com [mailto:mg-tabc@yahoogroups.com] On Behalf
Of WM HYATT
Sent: Friday, 27 February 2009 4:48 AM
To: Clive Sherriff; Mg-taBC@yahoogroups.com
Subject: Re: [mg-tabc] Oil pressure
Clive -
Racing oils, motorcycle oils, are a good choice for breaking in of flat
tappet engines. Such oils have high levels of ZDDP as these engines do
not normally use Catalytic converters. Years ago ZDDP compounds were
used in oils for their anti-wear properties, but their levels have been
reduced over the years as they have been shown have effect lifespan of
C. Converter.
Oils with a starburst API "SM" designation (passenger car oils) have a
mandated Max of .08% PPM of ZDDP whereas non SM oils such as
Racing/Motorcycle oils unconstrained by C.C mandate typically still are
available with much higher levels of ZDDP. E.g. Tom's Valvoline VR1
Racing oil has up to 1300 PPM of ZDDP. Castrol's Syntec 20/50 full
synthetic (can should say recommended for Classic Cars) i.e. non
Catalytic Conv. cars has 1200 ppm of ZDDP. Brad Penn Grade 1 Racing oil
(non synthetic) has 1500pp ZDDP. Classic Car Motor Oil
(www.classicmotoroil.com) offers an oil with 1500-1600 PPM of ZDDP
bottled by D-A Lubricant Co. www.dalube.com
ZDDP additives such as GM E.O.S,, ZDDPlus, www.zddplus.com, Camshield
www.camshield.com are available for initial break-in at each oil change
if a modern oil with API SM rating is opted for instead of possibly
harder to get & more expensive oils listed above.
Bill
TC4926
Odessa, Fl.
p
----- Original Message -----
From: Clive Sherriff
To: TWilson@indy. rr.com ;
mg-tabc@yahoogroups .com
Sent: Wednesday, February 25, 2009 5:51 PM
Subject: Re: [mg-tabc] Oil pressure
Tom,
Some seem content with 10 on tickover and 40
running. However I must admit I prefer to see
my oil at 50 / 60psi when running hot, and
about 20 at hot tickover in road use. (Racing
oil? - for a higher compression road or racing
engine I'd want a full 60 / 70 psi very soon
after my 25 psi at tickover revs)
Possibly a weak pressure spring - take the cap off
and fit a few small washers under the spring and
see what this does, (you can then replace or stretch
the spring if this seems the problem, otherwise
maybe the pump lid is worn and needs regrinding
dead flat to stop internal back oil seepage, but be
warned that less than 0.0015inch clearance
between the lid and the gears may well cause
a seizure when hot.
Rocker arm is easily checked by putting a thin
shim under the rear rocker post to block off the
oil supply and running for a short time (30 secs
should be enough, to see what that does to the
pressure.
Clive
Oxford UK
==================================
----- Original Message -----
From: Tom & Emily Wilson
To: mg-tabc@yahoogroups .com
Sent: Wednesday, February 25, 2009 8:21 PM
Subject: [mg-tabc] Oil pressure
I fired up the rebuilt "restored" engine for TC0272 this afternoon. It
started on the first crank and seems to be running pretty nice.
Oil pressure on the engine is still somewhat low. I'm using Valvoline 30
weight racing oil to break the engine in, and pressure at idle is 32
pounds.
At 3000 RPM it goes up to 40 pounds.
The only two things I didn't repair in the engine are the oil pump and
the
rocker arm assembly. So the options on oil pressure being low are these
two
things plus the pressure relief spring.
Is the pressure at a low enough level that I should be concerned about
this?
Thanks.
Tom Wilson
TC0272 & 0273
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