Holley surges while cruising

Discussion in 'Troubleshooting & Diagnosis' started by atakrator, Oct 13, 2009.

  1. deputyrob

    deputyrob Veteran Member

    866
    0
    Jun 22, 2008
    Canal Fulton Ohio
    my 700dp is doing this also, and i rebuilt it. so...you spray the Gumout in the holes while the motor is running right. plus i'll back the air bleed screws a tad. good info, thanks.
     
  2. Bikefixr

    Bikefixr Veteran Member Lifetime Gold Member

    1,643
    20
    Mar 13, 2006
    Jtaddeo: Your Holley 1850 is a 600, not a 650 cfm.

    To flush the bleeds out..look straight down into the carb. Open the primary choke blade. At the front of the carb you'll see the accellerator pump in the middle. Off to either side you'll see 2 small brass, pressed-in orifices. 4 in total. These are the bleeds that send air into the emulsion tubes and mix with the gasoline. There are 2 small diameter ones and 2 bigger ones. Run a length of fine wire down into those and swish it around. The blow your Gumout tube into these and blow out any crud and clean it out. Watch your eyes for blow-back.

    I do the blow-out while it's running.
     
    Last edited: Oct 16, 2009
  3. deputyrob

    deputyrob Veteran Member

    866
    0
    Jun 22, 2008
    Canal Fulton Ohio
    i got how to flush out the bleeds, and when i rebuilt my 700 i cleaned it very well and blew the crap out of everything with air. but does the engine need to be running... or does it not matter.
     
  4. Mr. Fast Eddie

    Mr. Fast Eddie New Member

    9
    0
    Oct 12, 2009
    East Tennessee
    I agree with the previous advice concerning Holley's and dirt. Aside from dirt, one thing you didn't mentioned was, your manifold vacuum. If you have a pretty rumppity cam, you may not have much vacuum. That being the case, you may need to change your power valve out for a lower numbered one. The stock power valve that comes in a holley will usually work in mildly modified engines...up to a point. If your engine has a pretty radical cam for the street the low vacuum allows the power valve to open while at cruise, causing it to surge and hop instead of simply run smooth at that rpm. This is caused by a low vacuum signal. Your car will run great under full or partial acceleration, but hops and skips while cruising. Typically whatever your vacuum is you will need a power valve with a number 1/2 that. If your engine is like mine, it has around 8-10 idling. I used a 5 power valve to remedy the situation. Many years ago I lost an engine by not fixing it soon enough. The extra raw gas went down the back of the intake and washed the back two cylinders rings out before I got around to sorting out the problem. That sucked on a new rebuild. Improperly adjusted/set up carburetors can kill your engine. Just my .02 cents. Eddie
     

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