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Technical Help!

Discussion in 'The Hokey Ass Message Board' started by Tim Gilley, Jul 5, 2016.

  1. Tim Gilley
    Joined: Jul 5, 2016
    Posts: 11

    Tim Gilley

    I have a fresh built 350 bored 30 over. Cold crank idle oil pressure is 50 to 55 psi. After driving about 30 miles idle oul pressure drops to 15 to 20. Any suggestions
     
  2. Bandit Billy
    Joined: Sep 16, 2014
    Posts: 6,528

    Bandit Billy
    ALLIANCE MEMBER

    You may not have any issue with that. I had a 71 LT-1 Vette for years that ran 40 to 50 pounds at speed but idled at 10 to 15. Solid lifter motor though, so it had restrictors in the journals. There's another thread on here that has no pressue at idle. Now that is an issue.

    My response will move you back to the top and like AAA, there will be folks by to help at any minute.
     
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  3. 1964countrysedan
    Joined: Apr 14, 2011
    Posts: 1,131

    1964countrysedan
    Member
    from Texas

  4. 69thumper
    Joined: Apr 11, 2013
    Posts: 12

    69thumper
    Member

    you need 10 psi per 1,000 rpm at operating temps. read Smoky's book " How to Hot Rod Smallblock Chevys"
     
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  5. Only drive 25 miles, welcome aboard!!
     
  6. Tim Gilley
    Joined: Jul 5, 2016
    Posts: 11

    Tim Gilley

    Rotella 15w40
     
  7. Tim Gilley
    Joined: Jul 5, 2016
    Posts: 11

    Tim Gilley

    It was the original 83 k10. So I bought a bosh. Same results
     
  8. Tim Gilley
    Joined: Jul 5, 2016
    Posts: 11

    Tim Gilley

    At speed it drops to 30 to 35.
     
  9. Tim Gilley
    Joined: Jul 5, 2016
    Posts: 11

    Tim Gilley

    I don't know if it has anything to do with it, but when I cut the truck off. It sounds like air bleeding off for a couple seconds?
     
  10. Make sure that you have not over filled the crankcase. Too high oil level will allow the crank to whip up the oil.
     
  11. Hollywood-East
    Joined: Mar 13, 2008
    Posts: 1,197

    Hollywood-East
    Member

    What is your temp. Reading? Heat will make it drop huge...
     
  12. Tim Gilley
    Joined: Jul 5, 2016
    Posts: 11

    Tim Gilley

    160 to 180
     
  13. slowmotion
    Joined: Nov 21, 2011
    Posts: 3,191

    slowmotion
    Member

    Sounds like your within a acceptable parameters to me. I wouldn't be too concerned. It's not gonna carry cold start-up psi once it's warmed up to operating temp, if that's what you're concerned about. Without digging out the old Motors Manual blue bible, I seem to remember GM calling for 10-15@idle, & 35-45@operating temps. Or somewhere's in that neighborhood. I'd drive it.
     
  14. elba
    Joined: Feb 9, 2013
    Posts: 613

    elba
    Member

    I agree with RACEMASTER . I bought a used 56 chevy that never had over 15 psi and drove it that way for two years.
     
  15. Diavolo
    Joined: Apr 1, 2009
    Posts: 810

    Diavolo
    Member

    Another chiming in that you're fine, probably even running oil a little too thick. The 10 psi per 1000 rpm is straight out of Bob's the Oil Guy as well. They seem pretty smart.
     
  16. Tim Gilley
    Joined: Jul 5, 2016
    Posts: 11

    Tim Gilley

    Just discovered something else that don't seem right. With the engine running, it has so much vacum you can't hardly get the oil fill cap off. The pcv valve seems to be free. I even removed it. It has a lot of vacum on the hose. It runs from one valve cover to the other with a t in the middle hooked to the carburetor. Should there b this much vaccum?
     
  17. You have a fresh air intake for pcv??
     
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  18. Tim Gilley
    Joined: Jul 5, 2016
    Posts: 11

    Tim Gilley

    I don't think so. Like I said, there's a vaccum line that goes from one valve cover to the other, a pcv valve on the drivers side. Teed into the carb
     
  19. So what's on the passenger valve cover?
     
  20. Yep, this is always what I thought to.
     
  21. You need to separate those vac lines down to one with one PVC valve on it. (To make sure. You have two PCV valve's ? :confused: ) Then use other valve cover to let fresh air in with a breather or vented cap.
     
  22. Tim Gilley
    Joined: Jul 5, 2016
    Posts: 11

    Tim Gilley

    No. Just one pcv valve
     
  23. Tim Gilley
    Joined: Jul 5, 2016
    Posts: 11

    Tim Gilley

    Just a nipple and a hose coming to the other valve cover where the pcv valve is
     
  24. ^^^^^ Ok, then go back to post #20.
     
  25. ^^^^^ Edit since you beat me. Picture please so we all can understand better.
     
  26. badshifter
    Joined: Apr 28, 2006
    Posts: 3,164

    badshifter
    Member

    Ok, slow down. The pcv valve is SUPPOSED to go from the back of the carb, (manifold vacuum) with ONE hose to ONE valve cover. The OTHER valve cover gets a BREATHER. Period. No T's ever. The PCV needs to pull air through, not create a vacuum inside the engine.
     
  27. deucemac
    Joined: Aug 31, 2008
    Posts: 1,055

    deucemac
    Member

    Your PCM system is a problem for sure. You should have clean filtered air enter one valve cover and travel through the engine by vacuum generated by the PCV valve scavenging blowby fumes and then carried to the intake to be burned . Run a hose from the air cleaner or use a filtered oil filler cap so that clean air only enters and a single nose from the opposite valve cover with the PCV in it . Preferably, the valve should be placed in a grommet at the valve cover. Make absolutely sure that there is a baffle at the point where the valve is plumbed or you will have oil consumption problems. That should cure your air noise upon shut down.
     
  28. Then the oil leaks begin. ;)
     

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