Page 2 of 2
Re: Which Oil is Best ?
Posted: Tue Apr 22, 2008 6:33 pm
by Toby
After our discussion on sunday, I watched my gauge and I seem to have 80psi cold, dropping to 65-70 when hot. I'm using a non detergent straight 40.
Re: Which Oil is Best ?
Posted: Tue Apr 22, 2008 11:52 pm
by 1936morriseight
Highlander,
As a Morris Eight owner myself, 1936 Series I Tourer, I think it unlikely that the two pumps you have are Morris 8, as they differ in many ways from S.V. Minor pumps. I notice however that there was a change in part numbers for the S.V. Minor oil pump body, idle spindle, spindle & gear and driven gear at engine number 5501. Prior to 5501 the pump body was 36682, idle spindle 36694, s&g 36691 and the driven gear 36693. From 5501 onwards the pump body was 36880, idle spindle 36883, s&g 36881 and the driven gear 36882. Perhaps the pump was increased in size at engine number 5501, hence your two pumps with deeper gears.
Jeff
1936morriseight
Re: Which Oil is Best ?
Posted: Wed Apr 23, 2008 9:16 am
by Trevor Wilkinson
The later SV oil pumps look the same as the early one but have a deeper pump housing and gears giving a greater volume.
I am running my SV minor on a 10/40 part synthetic oil and driving pressure when hot is 70+ psi. The idling hot drops back to 15/20 psi. From cold the pressure is off the dial.
The first thing to check for a low pressure reading would be the pressure relief valve and spring.
Re: Which Oil is Best ?
Posted: Wed Apr 23, 2008 12:04 pm
by 1936morriseight
Alister,
It may be worth checking the condition of both of your spare larger capacity pumps before fitting either, the following instructions apply to the Morris Eight pump, but may also be applicable to the Minor, as they both use a similar pair of rotating gears housed in a cast body.
Measure the radial clearance between the teeth of the gears and the pump body, this should not be more than ·006"
Check the end float on the gears using a straight-edge, this should not be more than ·003"
The Eight can also suffer low oil pressure, due to air leakage on the suction side of the pump.
Jeff
1936morriseight
Re: Which Oil is Best ?
Posted: Wed Apr 23, 2008 2:57 pm
by Ian Grace
Interesting. I wasn't aware that there were two depths of SV oil pump gears. Ther are three depths for the OHC pumps - the usual, then I have seen a very shallow one - which may have come from a very early engine (if it had not been heavily machined down at some point) and a deeper type fitted to later M Types.