Oil cannister regulator
- Thread starter lenmissy
- Start date
Len I believe you are talking about the fitting at the inlet of the oil filter?? It has about a .070 hole. The other regulator would be the bypass valve in the front of the valve valley under the intake manifold. Later oil pumps also have a bypass valve. These valves open and dump oil causing low oil pressure and are controled by spring pressure. You need to test any pump before installing to see it produces enough pressure and also adjust the bypass on the pump. The valley bypass is adjusted with a mechanical oil pressure gauge, the spark plugs removed, the cylinders lubricated and the engine spun with 12 volts. Use a spacer made of 1/8" pipe about .150 long on top of the spring if the pressure is low. Test it and adjust the thickness of the spacer to raise or lower the pressure. Do not streatch the spring it won't stay there. G.M.
The specification for the hole was .057 - .061
51 MERC-CT
Well-known member
This is a stock fitting with provision for oil pressure gage.
Don't think there are any new replacements available.
You could get brass fitting that would work, solder to plug, then re-drill accordingly.
I wasn't sure of the exact size of the restrictor hole but 31 years and 107,000 miles ago I drilled the one on my 39 out to .080. Also increased the size of the restriction hole in the filter return stand pipe to over .125. Engine still runs quiet and has 15 lbs pressure at idle and 45 lbs when the speed is increased. Engine has had nothing but Castrol 20/50 from start up. Also had the pan off for a leak at 75,000 and it is perfectly clean with no sludge at all. I wonder what this engine would look like with the 40s or 50s oil? G.M.