whoya

iTrader: (1)

Im getting a lower oil pressure reading in my old (89) dash gauge, dropped 10lbs over this season. So I hooked a mechanical one up to the back top of the block and the reading there is fine (20lbs higher).
Can there be a difference from just above the oil pad ( stock sending unit) compared to the top back of the block?
I didn't hook it up at/above oil filter pad because I wanted to compare the two and its a little bit of a pain to get to.
Thanks

ACrooks69

iTrader: (1)

My elec oil pressure gauge varys and drops down to about 50lbs from 65 abover 4300 to wfo 5500 down at the oil pad. I have a Dart SHP block with priority main. Up at the distributor, it says at 65 and doesn't vary at all. No clue why, but at least I'm not crazy. BTW I have a SBC.

mike tkach

iTrader: (3)

i dont trust the electric oil pressure guages,mechanical is much more accurate.

whoya

iTrader: (1)

Thanks guys

I wanted to make sure the oil pressure should be the same thru out the motor if read at a different spot. Was going to pull the motor because I was getting a reading of 45lbs on my Elec dash gauge at wide open throttle. The mechanical at top of the block is showing 67 at wide open throttle. Guess im good as I talked to an engine builder and said im fine.

Rookie

iTrader: (4)

I think it would vary in different parts of the block. Pressure should be the highest after it leaves the pump and before the greatest restriction. Pressure could be lower on the backside of the greatest restriction. Maybe higher before the crank and lower before the lifter valley. It is not a closed pressure system.

Agree electric gauges and senders do go bad. Mechanical are the best.

My Addiction

Pascal's Law, Pascal's law or the principle of transmission of fluid-pressure is a principle in fluid mechanics that states that pressure exerted anywhere in a confined incompressible fluid is transmitted equally in all directions throughout the fluid such that the pressure ratio (initial difference) remains the same. The law was established by French mathematician Blaise Pascal.

Rookie

iTrader: (4)

I understand pascals law, but that would be on a closed (confined) system. Oil running out the tops of pushrods leaking back to the block/tank is not a closed system. It should have the capability of max pressure after the highest restriction but if the restriction is not there it won't make the pressure. Not refuting just wondering. If it takes 80PSI to get through the crank but only needs 50PSI through the lifters I don't see it attaining the 80PSI after the crank.

I also could be looking at this all wrong though.

whoya

iTrader: (1)

I figured for sure it would vary in different locations. Maybe I should do a search how oil is routed thru a motor. Or I should just hook up my mechanical gauge to the other pain in the azz spot to get to.

Pinkley933

Spin them out.

mike tkach

iTrader: (3)

it has been my experiance that no matter where you attach a mechanical perssure guage,the pressure reading will be the same within a few lbs,atleast on a bog block chevy engine.i have tried it on the pad above the filter,in any of the threaded areas that oil flows through,and at the oil thermostat block[sc800 merc].we must remember that pressure is caused by resistance of flow,and in the case of an engine,the oil pump is capabal of producing more flow,and pressure,but has a bypass valve .the total pressure is changable with shims or different springs in the pump.what is important is the pressure in the oil gallys in the block,they feed oil to all aspects if the oiling system.