- Joined
- Dec 27, 2005
- Messages
- 151
I was wondering do u add or remove shims to decrease the pressure the valve relases at? and wot is the correct pressure. and does anyone have a pressure tester i can borrow?
cash said:Think back to the days when Minis etc had oil pressure gauges. A Mini relief valve was set for 60psi, when starting cold the oil pressure would shoot up past 75psi and a cooper oil pump would push it past 90psi, while at tick-over you'd see 50psi+.
Stick an oil gauge on your Commando and I'm sure you'll see the same effect
cash said:The Norton valve is a spring loaded piston that when compressed uncovers a ring of holes. (I think that's right there's that many variants). As those holes begin to open the hot thinner oil flows faster than the thicker cold oil. And as flow and pressure go hand in hand the higher easier flow causes a pressure drop. To get the same flow of thicker oil through the relief valve holes, the piston has to be compressed further and to do that a higher pressure is achieved.
But that (logically?) being due to the lack of pressure in the system and nothing to do with the relief valve I would think? *Pressure* of course, is seen to be the Holy Grail which it isn't really, as flow is just as important, and again from your own words this would appear to be be true?Apparently the works Commandos on the Island would lose all oil pressure due to heat without detriment.
cash said:I use now semi synthetic 20/50 and before that a good 20/50. I have always seen a pressure change with temperature on my Commandos and many others, but I can't ever remember any of them using 50 oil. Do you only use 50 oil? perhaps its the perfect balance for the Norton r/v.
cash said:I was taught to do all oil pressure checks etc on a motor and it's lubricant at working temperature. I cannot for the life of me see anything wrong with that.
It might be worth mentioning that pressure is, I'm sure, set hot and at 3000+rpm
No set RPM or engine oil temperatures are given for checking pump pressure in any manual that I am aware of, although if you could say where you found this info I would be grateful?
cash said:It might be an idea to replace the timing side joint with a new one and fit it dry. There is a feed drilling there but I can't for the life of me remember what it does. I'll have to read the book.
cash said:Section C22 of the NVT workshop manual for the Mk3 850 states " Oil escaping from the valve returns to the feed side of the pump."
I knew there was a difference but could not remember the detail. As you said the Mk3 timing side cover isn't drilled, but I was unsure if my old Mk1's cover was.