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engine readings: minimums and maximims

Discussion in 'The Garage' started by 78Suburban, Oct 10, 2005.

  1. 78Suburban

    78Suburban 1/2 ton status

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    what is the lowest psi my oil gauge should ever read, and what is the highest?
    what about teperature?
    what about amps?

    I want to know when to shut off the engine to aviod damage, or my gauges are useless..

    I have a stock 350 from 1978.. thanks :bow:
     
  2. 78Suburban

    78Suburban 1/2 ton status

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  3. 1977k5

    1977k5 3/4 ton status Vendor

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    Your engine needs at least 7 psi of oil pressure at idle, and at least 10 psi for each 1000 RPM (i.e. 6000 RPM needs 60 psi). Temperature should be below 225. I don't know about amps, but you should read no more than about 15 volts.
     
  4. 78Suburban

    78Suburban 1/2 ton status

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    I cranked it up today (I still don't have the timing set right) and it was idling at like 30 psi.. is that bad??
     
  5. 1977k5

    1977k5 3/4 ton status Vendor

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    Nope, when mine is cold it will push 60 (aftermarket oil pump and whatnot though). You really can't have too much oil pressure. :D
     
  6. Brocky

    Brocky 1/2 ton status

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    On cold start mine goes almost max. Relaxes after. Just make sure it moves when u give her some fuel.
     
  7. MOBK5

    MOBK5 1/2 ton status

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    Acctually, I think you can have too much oil pressure. If its too high instead of lubing your bearings, you will wash them out and prob. have some spun bearings.
     
  8. 78Suburban

    78Suburban 1/2 ton status

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    but that's not likely with a stock motor, right?? :confused:
     
  9. mouse

    mouse 1/2 ton status

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    You're no where near too high. I have seen race engines produce 100 psi plus.

    While we're talking pressure, usually a high volume oil pump will give you a bit higher pressure, but more importantly, more flow.
     
  10. mciahpv

    mciahpv Registered Member

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    I would agree -- there is a such thing as too high, but you pretty much have to work to get it there (or turn about 8,000 rpm) You'd probably blow off your filter before you ran into more serious problems, although depending on the situation, blowing off the filter could be VERY serious.

    Mine turns about 60 when I first crank it (383 roller) but drops quickly as it heats up.

    If you're having trouble keeping the psi up, it probably points to some more serious internal problems, but there's always the cheap and easy redneck fixes (both of which I've used on occasion):

    1: Up your viscosity. I've run up to 50 weight -- works great here in the South, but probably not so great if you're more towards the Great White North.

    2: Monkey with your oil pump spring. Not the most sophisticated solution, but it will work, and it's free. It's amazing how much PSI you can gain from just a few tugs to stretch the spring. Again, not exactly SAE recommended, but if you're on a budget and are trying to limp things along, all it takes is a decent socket set and about an hour...
     
  11. 78Suburban

    78Suburban 1/2 ton status

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    as long as I stay above 7 psi I'm ok though, right???
     
  12. mciahpv

    mciahpv Registered Member

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    Yeah, if it's idling at 30, you're fine. That's about what mine runs once it heats up. I wouldn't worry unless it dropped below 15 or so.
     
  13. mouse

    mouse 1/2 ton status

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    7 psi at idle is a bit low, but as long as its not rattling, you could be OK for a while. You could try going to a slightly heavier weight oil, or changing the oil pump to a high volume unit to increase pressure. Generally, though, low oil pressure is a result of bearings wearing out, although leaks and other circumstances could also affect it.

    BTW, your gage could be wrong, especially if you're using an old, stock gage.
     
  14. 78Suburban

    78Suburban 1/2 ton status

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    my oil pressure isn't running on 7. its running on 30. Someone on this thread said 7 was the minimum.... I was just asking because I want to know what the minimums and maximums to watch for in the gauges I just installed.
     
  15. SUBFAN

    SUBFAN 1/2 ton status

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    30 psi is fine at idle. With that idle psi, it will probably run 45-50psi at cruise. Both are fine for oil pressure. Just watch now for variations from these. If your cruise pressure starts dropping, Shut it down and smell for gas in the oil.

    If the idle psi goes down, and the oil is good and clean, and the same viscosity, hope that it is a bad gauge/sender....
     

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