Any Holley experts? Carb wont stop running rich

Discussion in 'Engine Topic' started by CarAteMyMoney, Sep 5, 2009.

  1. CarAteMyMoney

    CarAteMyMoney Member

    Jun 26, 2004
    Queens, NYC
    I've got a holley 600 vac secondary on my 355, it's got ported sportsman II's, a hot cam, single plane weiand, and true duals

    I've got a holley red pump and regulator, set to 5 1/2 psi.. fuel level is below the sight plug on the float, adjustment screws are about as lean as you can go on the carb

    the idle is about 850, if i mash the gas it shoots a fireball out the carb, there's some preignition when i shut the car off, and it's definitely running rich

    where should i be looking to smooth the idle out and make it not choke me out?
  2. 79camaro2001

    79camaro2001 Veteran Member Lifetime Gold Member

    May 4, 2003
    Monroeville, PA
  3. Stroked72SS

    Stroked72SS Veteran Member Lifetime Gold Member

    Oct 26, 2005
    Bryan, Texas
    What does the car have to Idle at inPark, so it will Stay Idleing in gear??

    What is your manifold vacuum once the engine is warm ....What power valve is in the carburator??

    These are the first issues to resolve before other measures come to play...

    Let me know, and I can help you fix this issue..

    and just like
    79camaro2001 asked....what is your initial timing?? and your total timing...knowing this will help rule it out, or determine if it is a problem

    PM or E-mail me if you like.....

    Last edited: Sep 5, 2009
  4. CarAteMyMoney

    CarAteMyMoney Member

    Jun 26, 2004
    Queens, NYC
    As far as I know the carb is completely stock, and i'd like it to idle at 800-850 in neutral

    as far as initial timing, what should I have it set at? is 4 or 6 good?
  5. my71bmf

    my71bmf Veteran Member

    May 26, 2008
    Tulsa, Ok
    Initial timing is relative. Total is the important number imo. Make sure every thing inside is good and tight. I had a loose power vavle once and that fouled plugs in a hurry.
  6. Dave Nelson

    Dave Nelson Veteran Member Gold Member

    Dec 19, 2003
    Vineland N.J USA
    If the engine has backfired you will have to replace the power valve, this would cause a rich condition,and as others have said check your timing.
  7. muscl car

    muscl car Veteran Member Lifetime Gold Member

    possible causes :

    timing not set properly like to retarded .....try bumping up the initial timing and see if that helps

    possible blown power valve this will cause excessive wet/rich fuel mixture at idle

    now to fix this issue check the timing and power valve and if they're okay then i would try maybe drilling 2 small holes into the primary throttle blades to help clean up the idle circuit

    the other is placing (2) small .018 gauge wires ea 3/4 to 1" long into each idle feed restrictors of the primary side metering block .this will fool the carb into thinking it's alot smaller in cfm allowing a leaner mixture for the idle circuit

    pic of a .018 wire inserted into the IFR ports of the metering block

  8. Stroked72SS

    Stroked72SS Veteran Member Lifetime Gold Member

    Oct 26, 2005
    Bryan, Texas
    Forgot the important part...

    Your total timing should be about 38BTDC...and with the 355 if you have lass than 10-1 Compression, and steel heads, the motor should like that range very well. (although...every engine is different)

    THen once you set the timing, there's a good chance you'll need to lower your idle speed at the Carb...once you've got that where you need it, it'll be unlikely that the transfer slots are uncovered (this is what you want) if you have the idle screw open too much the transfer slots begin to bring in the main circuit of the Carb...

    CHeck your Vacuum ..warm, in gear, and take the number you get and divide it in half

    If you get 11 .in of Vacuum...Half is 5.5

    You need a 5.5 Power Valve....

    That will allow the vacuum to hold the Power Valve closed, until you tip into the throttle (Vacuum decreases) then the power valve is designed to richen the transition from the idle to main circuit without a lean condition (Stumble)

    Good Luck!!!!:cool:
  9. markw

    markw Veteran Member

    Jun 6, 2009
    A 600 vac sec carb is set up lean with a heavy secondary spring. With a single plane manifold you need 14-18 deg initial with 36 at 300 total. Try a purple secondary spring with a quick change cover. Set the mixture screws with a vacuum gage. A lean mixture can misfire and send unburned gas out the tailpipe and burn your eyes. Fireball out the carb = lean. Might need a bigger pump shooter. Make sure pump cam is adjusted properly. Set transfer slots to show .020 (seen when you flip the carb over). They should look like square holes. Stepping into the throttle slowly from idle to full throttle the carb uses the idle circuit, then the transfer slots, then the main jets, then the power valve, then the secondaries. A power valve open at idle means nothing. It only richens the main circuit which hasn't even started yet.
  10. CarAteMyMoney

    CarAteMyMoney Member

    Jun 26, 2004
    Queens, NYC
    I set the timing to 12 degrees base and the run on went away

    I took the car up and down the block and it's definitely running pig rich off idle and while it's cruising.. it's set at 4 3/4 psi or so but definitely under 5.. should I bump it up to 5 1/2 or 6?

    When I tap the gas lightly it bogs a bit and then goes, and sometimes when I slow down after going down the block it'd stall when i'd come to a stop, and start 5 minutes later or so.. it also feels pretty sluggish through the rpm range in regular driving

    I'll pick up the secondary springs, is there anything else I should look at?

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