Oil Pressure anatomy and gauge meanings

[Dominic Torreto]

Just wanting to know what are bad specs for oil pressure is to high or to low. What kinds of things cause to low of oil pressure or to high and what are basic oil pressure readings for a high performance 440 mopar 1970 charger. Any little knowledge greatly appreciated.

 

[70rr-brian]

For starters I wouldn't trust the stock gauge any further than I could throw it....(OK, bad example I could probably chuck that thing a few hundred feet.) But seriously, an aftermarket gauge is the only way to go. That said, I will give you my observations from having "stock" oil pumps and high pressure oil pumps.

On the stock pump when cold with 20w50 oil I would expect inital idle pressure to be around 60. Once up to temp idle around 20lbs and cruising between 40-50.

With high pressure when cold with 20w50 around 80 on initial idle and at temp about 30 at idle and cruising between 60-70.

The stock pump is probably OK for most street driven applications less one exception... A solid roller. These need higher idle pressures and using a high pressure pump is good for these apps.


Low oil pressure could be a bad pump, collapsed oil filter...could be a bad sending unit and everything is actually ok.

Just my 2 cents.

 

[Dominic Torreto]

I appreciate the info as for the aftermarket oil pressure just got a digital one. My stocker isnt even working. I put positive electricity on the wire and the gauge still did not move so I bought a new gauge. If that doesnt work I am going to change the oil pressure switch.

 

[RustyRatRod]

10 PSI for every 1000 RPM is the accepted minimum.

 

[Meep-Meep]

My stocker isnt even working. I put positive electricity on the wire and the gauge still did not move so I bought a new gauge.

Problem: You need to ground the sending unit wire in order to make the stock gauge read. If still no response then your problem is confined to the dash or perhaps the sending unit wiring connection.

Normal oil pressure is quoted at I think 50 lbs at 1500 RPM. The exact info is in the FSM. The high perf "black" relief spring will put the PSI to 70.

Lower than factory spec oil pressure can happen from things like internal clearances growing due to use assuming the engine is unaltered and no screw ups from poor assembly along the way. There are plenty of man made oil pressure issues like forgetting a galley plug or putting parts together that don't meet spec. These days I imagine using 5/20 oil can cause some low oil pressure readings!

 

[red 69 runner]

install a mechanical gauge that will give you the best reading.

 

[daredevil]

For starters I wouldn't trust the stock gauge any further than I could throw it....(OK, bad example I could probably chuck that thing a few hundred feet.) But seriously, an aftermarket gauge is the only way to go. That said, I will give you my observations from having "stock" oil pumps and high pressure oil pumps.

On the stock pump when cold with 20w50 oil I would expect inital idle pressure to be around 60. Once up to temp idle around 20lbs and cruising between 40-50.

With high pressure when cold with 20w50 around 80 on initial idle and at temp about 30 at idle and cruising between 60-70.

The stock pump is probably OK for most street driven applications less one exception... A solid roller. These need higher idle pressures and using a high pressure pump is good for these apps.


Low oil pressure could be a bad pump, collapsed oil filter...could be a bad sending unit and everything is actually ok.

Just my 2 cents.

Whats the basis for the solid roller to need more pressure?.

 

[Dominic Torreto]

I had to buy a special socket. I also got the aftermarket digital gauge to work good with it. I have to say though this thing is really fun to work on and on top of that being an import 4 banger person I really learn things a lot easier on the mopars than on the importants and I can comprehend on how things work on the mopar big blocks than you can with a fuel injected sophisticated car.

 

[70rr-brian]

Whats the basis for the solid roller to need more pressure?.

“Going to a solid roller in a street application, the biggest thing is the bearings on the wheel and axle. It’s important to keep oil on that, so that is where the pressurized oil is beneficial. The solid roller stuff is designed for high rpm for a short amount of time and drag racing. In a street application, guys will believe the engine is staying at low rpm and is just idling around, so that will be easy on it. In truth, at low rpm the crank is not slinging much oil up to the lifters, so there isn’t any oil up into the wheel and into the bearing. The result, especially with high spring pressure and aggressive lobe design, is you end up killing the bearing on the lifter, causing a failure."

- - - Updated - - -

I had to buy a special socket. I also got the aftermarket digital gauge to work good with it. I have to say though this thing is really fun to work on and on top of that being an import 4 banger person I really learn things a lot easier on the mopars than on the importants and I can comprehend on how things work on the mopar big blocks than you can with a fuel injected sophisticated car.

You getting decent oil pressure then I take it?

 

[RustyRatRod]

Not necessary with MRL roller lifters. The wheels are lubricated with pressurized oil.

 

[cr8crshr]

My 383 build...Yes still struggling with it...when fired up using a high volume oil pump is at 80PSI with a mechanical gauge along with the dash idiot light. FSM [Factory Service Manual] specs are 60 - 65psi. Most FSMs will say the same thing...Hemi's not included here for discussion purposes. That is using 30 wt oil too...

 

[70sixpack]

Quick question. Have a 70 GTX with the rallye gauges which I just rebuilt and when I turn the key to the on position the oil pressure gauge pins to 80+? any ideas...

 

[okiemopar]

Sounds like a bad gauge. some thing is not right with it

 

[70sixpack]

Sounds like a bad gauge. some thing is not right with it

It worked 2 years ago, that is when it was pulled apart for a full restoration. Not sure why it does not work now?

 

[okiemopar]

If it is pegging out sounds like it is grounding out. May have shorted on the inside of the gauge. Mine stopped working and I got new gauges from Classic Ind.

 

[70sixpack]

I found it it was the circuit board. Mine had a few pins loose, so I bought one off EBay. I did not know it was repaired until I received it. I installed it anyway and that was the cause of the problem.

 

[okiemopar]

I gebought a new circuit board with the electronic limiter built in it with the gauges, my new oil gauge just reads up to 30-35 lbs and it dropped just a little so I hooked up a temp. mech. gauge and it reads 50 lbs at idle. So my new gauges are a way off. My new gas gauge never worked right it would go up tp 1/2 some times and 3/4 some times but I just started watching my miliage and gassing up that way. Glad I checked out my oil pressure before I pulled the motor