Please someone tell me how the timing case gets the lubrication it needs. I understand that the oil pressure relief valves diverts some oil to the case but my question is this ; Does the pressure relief valve divert oil to the case only when the pressure of oil exceeds the limit that the relief valve can stand or is oil somehow fed to the timing case in a steady stream via the relief valve ?
What should the maximum oil pressure be for a 1962 Norton 650 SS before the relief valve diverts oil please?
In order to check oil pressure I can remove a 5/16 BSF bolt from a position just below the oil pressure relief valve assembly and attach a banjo bolt and banjo to feed an oil pressure gauge but as space of only 8mm from bolt thread to the obstruction of the pressure relief valve assembly does anyone know of a supplier of a suitable banjo construction that could accommodate such a restriction please?
I would not worry about…
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The pressure relief is set…
The pressure relief is set to 50 psi, needed for cold starts and thick oil. As Robert says the timing chamber is well oiled by splash through the main bearing and holes drilled into the side into the crank chamber. Rule of thumb is you want to add a worry gauge is 10 psi per 1000 rpm but it will drop as the oil thins out, the revs rise and the centripetal forces at the big ends pull the oil out faster than the pump can supply. A simple oil light that goes out at 10 psi is much more useful.
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Oil Flow
From the oil pump, the rockers are HP oiled for late engines. Early are from scavenge low/puke pressure return line
The intake rocker side has a drain passage on the extreme right
It drains down the head passage to meet the rear of the barrels behind the RH cylinder.
It continues down to the cases and further 1/2" then right turn/horizontal to drain out and into the timing chest
When full it drains out the rear passage to the rear of the oil pump and across to the rear wall of the cases to become "scavenge" for the oil pump to return to the tank
Yes this is in addition to over pressure relief when cold Warm engines almost never exceed pressure relief and therefore dump into the timing chest.
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Irving (author of the…
Irving (author of the classic "Tuning for Speed") writes in "Automobile Engine Tuning" "a copious supply (to rocker shafts) ...given more in the interests of silence than preventing wear". So the reason for the change to high pressure rocker feed was probably only to make things quieter. Seems logical...has anyone has any trouble from the old low return pressure rocker feed?
The oil pump was first used in the 30's to deliver lots of oil at very low pressure, because ball bearing engines had nothing to block the delivery to raise pressure. With the Dommie etc, the only plain bearings are in the big ends, and as John says the rotation sucks oil out of the pump anyway.
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I would not worry about lubrication in the timing area. Its a malestrom in there , and there is not much that needs more than a dribble . Too much and you will drown the ignition system. Norton did not recommend the fitting of oil gauges as the pressure could vary so much that owners would worry. My 1960 big ends are still hanging in there although i would have said the wear i found there in 1990 was worrying enough .