I’m at dragway 42

Discussion in 'Small Block Tech' started by Mark Demko, Jul 24, 2020.

  1. Mark Demko

    Mark Demko Well-Known Member

    Another curious question, if I were to remove the power valve, which IM NOT:rolleyes: what jet size would provide the same amount of fuel that the power valve adds, or is that one of the unknowns and the reason why some racers remove it?
     
  2. Bens99gtp

    Bens99gtp Well-Known Member

    I don't know why some don't run it.......I run it in mine with no issue.

    But if you remove it you need to add about 6-8 jets to balance things out.

    Another of raceway dont make even 5" of vacuum so getting the pv setup can be a slight pain
     
  3. telriv

    telriv Well-Known Member

    In a full race condition you DON'T WANT a P/V determining amount of fuel, AND you cannot cross jey as easily.
    A P/V is normally used for street/race where fuel economy is an important factor. Not so much in a racing situation.
    JMHO

    Tom T.
     
  4. Fox's Den

    Fox's Den 22 years of racing the same 355 Buick motor

    Without the PV on the street you would be way over rich. It is really a race only item since you have to jet it up fairly high.

    When I had the TA 510 cam in the vac was at 5 so I had to put in a 2.5 power valve

    You want the pv to come in before the engine pings at 1/3 throttle. There is that point before cruise to where it comes on at doesn't take that much throttle to get to the 6.5 pv in most carbs so you could try a 4.5 or a 5.5 see how it is at it's part throttle push.

    You would have to use a vac gauge while you are in 3rd gear and probably going around 45 -50 and see how much it takes to get to 6 or 5 or 4 on the gauge if you want to play with something like that.

    mostly you put the 6.5 in there and leave it alone unless the cam brings it on too soon then go lower.
     
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  5. Bens99gtp

    Bens99gtp Well-Known Member

    by the birthsheet it has a 4.5pv.

    What I have been told by general rule of thumb. 1/2 of what ever idle vacuum reading is generally a decent starting point.


    The lower the number the slightly more delayed the power enrichment is. The higher the number the sooner it kicks in


    But this is a starting point it can take some tweaking.

    I run one in mine it does help keep my car from loading up on the return road.....I tried it square and you could clearly hear it struggling running 3000 down the return road under light load......even with it I feel I need to play with my intermediate air bleeds
     
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