As for many I don’t really trust electrical o/p gauges so installed this one in our Mk2 this afternoon. Made up a bracket that fixes using the knurled console screw - so all can be returned to standard. Curiously measures exactly as the electrical gauge - original Smiths - did not know this until I recovered it, not the easiest job on a Mk 2! Paul
Nice gauge, almost looks like a Smiths item. So tell us what pressures are you getting at various engine speeds when hot. I assume this is on Mark II with 3.8 litre engine.
Hi John, my car is a 3.4 with standard oil pump. Running 20W50 I have about: 25 psi at 700rpm; 50 psi at 2000rpm; and 52 psi at 3000rpm. All with engine well heat soaked. Our XJ6 runs significantly more but has a spin on conversion and a series 3 pump. Paul
Hi Paul; where did you mount the pressure guage pickup? did you remove the old sender and replace it? It looks hard to get at… thanks, David
Hi David, correct. Removed the old sender altogether. The new gauge came with a correctly threaded union - just nipped it up on yellow plumber’s tape and routed the capillary tube through the big cable grommet in the firewall. It is difficult to get at took air cleaner and intake plenum off and used shortened spanners. Paul
Paul, That seems like very good pressures. My 3.8 with 20W50 runs about 20 PSI at 700 RPM hot and about 40 PSI at 2500 RPM hot… The 4.2 XK engine in the later Jaguars has, I believe, a larger pump and higher pressures across the board but don’t think a spin on filter would make any difference. John
Hi John, expect you’re right about the spin on. Was more of a management regime - sometimes it does not start for a fortnight - taking a while to raise oil pressure. The spin on has an anti drain back feature - makes oil pressure almost instantaneous. We don’t have that problem in our Mk2’s as the filter is at sump level. Good to understand what pressures others are running - thanks for the Data point. In the racing preparation handbook I have it suggests that oil pressure be 40psi hot, at 3000rpm for competition. Paul
One point I might note with my 3.8 rebuilt engine when I start it, is that I do not give it any throttle when I first start it for almost 20 seconds. I wait for the valves to get fully lubricated which I can hear the tone changing when they are fully lubed. I also have a spin on conversion and by my Smiths gauge, all appears well well even when VERY warm. I am running 20-50 oil during the summer and 10-40 during the winter months. At idle my engine sounds like a room full of sewing machines!!
Gerard
The only change I know of is the increased bore of the 4.2 low pressure (sump pick-up) pipe. There were also various versions of relief valve but I never heard that the main trochoid pump changed between 3.8 and 4.2 engines.
Cool. Thanks for the info. David