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Thanks for the Weber help, the fix was...

Discussion in 'Technical Q&A' started by Doug, Apr 4, 2004.

  1. Doug

    Doug Formula 3

    Nov 13, 2003
    1,467
    Louisville KY
    Full Name:
    Doug
    #1 Doug, Apr 4, 2004
    ...larger idle jets.
    Back to the symptoms, in case anyone has similar problems. The car is a '76 GT4.
    Car was crackling/popping and backfiring on deceleration and the rpm wouldnt drop when I shifted. My idles were 45 and my mains were 130. The car came with a set of 135 mains and I ordered some 50 and 55 idles. I put in the 135 mains and the 55 idles and everything is cured. I understand that the original leaness was due to too small idles, but I can't figue out what caused the rpm to stay high when shifting. Go figure.
    If anyone is interested in some 45 and brand new 50 idles as well as some 130 mains, let me know or make an offer on some or all.
     

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  2. f355spider

    f355spider F1 World Champ
    Rossa Subscribed Owner

    May 29, 2001
    17,306
    USA
    #2 f355spider, Apr 4, 2004
    Doug,
    great info! What your plugs for loading up....I know when I richened my main jets, I needed to go up one heat range on the plugs to keep from fouling...I think I was using a NGK 6, but the car needed a 5. But I went up several sizes...they are 125s on a 78-79, and I went to a 140.

    Dave
     
  3. pma1010

    pma1010 F1 Rookie

    Jul 21, 2002
    2,559
    Chicago
    Full Name:
    Philip
    #3 pma1010, Apr 4, 2004
    Doug
    It was probably richening the mixture when you closed the throttle.
    Glad you're set.
     
  4. Doug

    Doug Formula 3

    Nov 13, 2003
    1,467
    Louisville KY
    Full Name:
    Doug
    #4 Doug, Apr 4, 2004
    Philip, how does it run rich on smaller jets when I close the throttle. That is what confuses me. I put in larger idles and that cleared up the problem.
    Dave, I am running Champion N9Y's based on some advice from this board gapped at .26. I also have a single dist. electronic conversion with a Mallory Unnilite ignition.
     
  5. Peter

    Peter F1 Veteran
    Rossa Subscribed Owner

    Dec 21, 2000
    6,406
    B.C., Canada
    #5 Peter, Apr 5, 2004
    Hey, that's what happened to my car too! Previous mechanic installed 45's for whatever reason. Car stumbled alot when pulling away from stops. Put in the correct 55's and beauty since.
     

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  6. snj5

    snj5 F1 World Champ

    Feb 22, 2003
    10,213
    San Antonio
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    Russ Turner
    #6 snj5, Apr 5, 2004
    Doug - am looking at a Mallory Unilite single distributor as well - who did yours and what did your best advance settings turn out to be?

    many thanks
    Russ
     
  7. Doug

    Doug Formula 3

    Nov 13, 2003
    1,467
    Louisville KY
    Full Name:
    Doug
    #7 Doug, Apr 5, 2004
    Russ
    Mine is a homke fabricated unit by the PO. He used an original distributor and then fabricated it to accept a UNilite ignition and a Mallory cap/rotor. I am out of town for a few days, but I can get you the part numbers when I get home if you would like.
    I set the advance at 1000rpm to 7deg. I can't recall the higher rpm advance off the top of my head.
     

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