Having finally sorted out the engine oil pressure, I thought I'd put the original oil pressure gauge back in the car. For ages now it's had the Recetech mechanical gauge that I bought a while ago. This is a truly wonderful instrument especially from the point of view of the wonderful clarity of the display, and any other car I build will probably have these mechanical instruments in it. However, it has two problem in that it does not have any illumination (I bought the cheaper one..) and the appearance just doesn't match the other instruments.
So, I connected up the old sender again and was rather dismayed by the horrible set of readings it showed. Whereas with the Racetech instrument it never read less than about 22psi, even when idling slowly with the oil very hot and never below 40 psi with the engine operating at any reasonable rpm the new (old) gauge never seems to struggle above about 20psi.
I lent my sender to Trevor Turner a while ago and he eventually bought a new one from Greengauges and got much better readings. Like him, it has to make you wonder about the quality of manufacturing that goes on at Caerbont (the Greengauges parent company). I will certainly not be buying their instruments again.
All the same, the car's dash looks better again as the instruments at least match.
I also adjusted the car's timing again. I'm understanding rather more what to do with this now. When I had the car rolling roaded the best power was achieved with a surprisingly small initial advance (about 3° BTDC). I've fiddled about with this a lot since and it does seem to be best to leave it here. If I set it to the recommended SD1 setting (6° BTDC at 1200rpm, no vacuum) then two things happen. First of all the car is very prone to pinking. Secondly, it runs hot; not very hot but much more marginal than the more retarded setting. So, I'll leave it at about 3° as it seems much happier there.
In fact, I took the car out for a run and it ran beautifully, I'd sort of forgotten how much fun it was!
I ordered a new oil pressure sender from Merlin Motorsport and tried fitting it at the weekend. Continuing the obvious high standard of CAI instruments it read about half what the previous one did, which in itself was about half of what I got with a mechnical gauge and which Trevor Turner got from a new sender.
So, I'll have to send it back and get another one. The stunningly low quality of these instruments continues to amaze me ...
in case you've got to this frame directly and can't get out, go here.