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RPM questions

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by mudfanatic, May 6, 2000.

  1. mudfanatic

    mudfanatic 1/2 ton status

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    Location:
    Aloha, Oregon
    My rig has been acting erratic lately.
    My truck runs very rough when cold now, oil pressure sits at around 60 psi when cold, and when I hit the gas it blows out grey smoke. When the rig warms up the oil pressure drops to between 20 at idle and 40 while driving and the engine smooths out. Until the engine hits around 160 degrees if I stop my rig will idle ok, but after 160 degrees if I stop the idle will drop to around 350-400. If I take my foot off the brake the edle goes up to around 700, unless the lights are on then it stays low. This isn't just the tach, I can hear a definite change in operation of the engine.
    Any opinions?
    need to know more specifics that I may have left out?
    it's a 77 chevy blazer with a 350, HEI, Automatic th350
    Edelbrock performer 650 CFM carb with electric choke,
    stock alternator, gage says that it puts out around 14 volts at 700 rpm's and 12 volts at 350-400 rpm's, and a constant 30 amps. New battery!but the rig is setup for duals so I think that that is why it is pumping out 30 amps, trying to charge a battery that's not there. Or maybe I don't have my Ammeter wired right.
    Dan
    '77 K5

    <font color=red>mudfanatic</font color=red>[​IMG]
     
  2. Gold Rush

    Gold Rush 1/2 ton status

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    It sounds like your rig is possesed! Seriously the high oil pressure when cold then dropping to lower after it warms up would most likely be slightly worn main bearings and the smoke is from worn rings. The low idle after warming up and running rough while cold could be your carb. I am having problems with my Edelbrock electric choke 600 CFM carb due to the change in weather to warmer conditions right now. In a week or so when the weather decides to start staying warm I'll have to change my choke settings and idle settings to compensate for the warmer weather. Don't know why but I've had to do that in the spring and fall ever since putting the Edelbrock on. Hope this gives you some helpfull ideas to check. Good luck with it.

    David 75K5

    [​IMG]
    http://www.renschler.org/~goldrush
     
  3. Eagle86K5

    Eagle86K5 1/2 ton status

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    Location:
    Whitehouse, Ohio
    When ws the last time you checked the module in the distributor. My car was acting just like that till it finally died, I found no spark. I was going to replace the coil and whatever else I could find when the chap from Autozone said it was the module. I brought it in and he tested it, there are 8 different test they go through, it failed 7 out of 8.replaced it and she ran just like a new one.

    <font color=green>[​IMG]Eagle86K5[​IMG]
     
  4. walrus101

    walrus101 Registered Member

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    Location:
    texas
    i thought the oil pressure was based on the cam, whether low or high? just a thought. my friend s-10 is doing this and his throttle position sensor is caput. i don't know if yours would have this or not.
    not much help, but just some thoughts.

    walrus101

    goo goo gaju
     
  5. Eagle86K5

    Eagle86K5 1/2 ton status

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    Location:
    Whitehouse, Ohio
    Crankshaft drives the cam, cam drives the distributor and the distributor drives the oil pump...

    <font color=green>[​IMG]Eagle86K5[​IMG]
     

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