Running in new 425 build. Oil pressure?

Discussion in ''Da Nailhead' started by Doomsday Graphix, Sep 12, 2020.

  1. Doomsday Graphix

    Doomsday Graphix 65 Wildcat

    So I have had my 425 fully rebuilt with new parts etc etc.Running in at 2500rpm I’m getting 38 to 40 psi. This is with thin running in oil. It drops off dramatically at idle. Any comments on what it should be at idle. I know oil pressure drops off on these motors substantially.
     
  2. Bigpig455

    Bigpig455 Fastest of the slow....

    40-45 at 2500+ RPM and 10 at idle is just fine. These motors never had or needed anything more.
     
  3. wkillgs

    wkillgs Gold Level Contributor

    Agree. The relief spring can be shimmed for a bit more pressure, you'll get maybe 45-50 psi at most, less when it warms up.
    The main bearings/crank get oiled first in the Nailhead. Oil doesn't get to the lifter gallery and rockers till the oil gets to the front of the engine, after the bearings got fed.
     
  4. suntreemcanic

    suntreemcanic Well-Known Member

    I just rebuilt my 425. Have real good clearances on mains and rods. With 10-30 start-up oil, I also have 38 t0 40 lbs. with a new Melling oil pump. I have not idled mine yet when warm All my lifters sound good and I am getting good oil flow to all my rockers.
     
  5. TrunkMonkey

    TrunkMonkey Well-Known Member

    My nailhead has 35-40 (Florida) hot, 15-20 at idle. And clappy as a ham.
     
  6. John Codman

    John Codman Platinum Level Contributor

    My 425 is happy with about 40 on a cool day and a hair less when it's in the 90s (which is most of the time here).
     

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