A mechanical oil gauge may bounce if you are low on oil. An electric oil gauge may bounce if the sending unit or the gauge itself is faulty and of course you are low on oil.
how to install the oil pressure gauge on a Chevy 350 small block
The one on the top rail behind the distributor is 1/8"NPT.
In back of engine, on top, drivers side of distributor.
There is a 1/8"npt port on the back rail of the block near the distributor hole.
Check your oil pressure gauge, if your just going by what it says the gauge might be wrong Iv had this happen bout 4ish times and its always the tube running to the oil pressure gauge is pinched so its not getting a good reading.
It is on the driver side head of the engine.
Screw out the oil sending unit. Put a "tee" back into the hole. Screw in the oil sending unit for the light AND the fitting for the mechanical oil gauge.
Yes, that is a good place for an oil pressure guage. Try to keep the tube away from exhaust heat.
The temp gauge sensor screws into the driver side head atoms #2 and #3 plugs. The volt gauge hooks up to any ignition on hot wire and the other wire to chasis ground. Oil pressure gauge is just behind the distributor.
The fuel pressure is not adjustable on that vehicle.
you can buy the gauge at any auto store or even walmart and there are directions with the gauge.
195 degrees F