FUEL OR SPARK

Discussion in 'General Chevy & GMC Pickups Talk' started by 74X4Burb, Apr 26, 2005.

  1. 74X4Burb

    74X4Burb Member

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    I got my 71 running realy good, until it grabs 3rd and I kick in the secondaries. then it just starts missing like theres no tomarrow this truck has always done this, no matter what carb I have on it what I set the timming at. it just starts running like crap when i open her up,it has a hesatation right off idle too but then again thats only if I lay into hard. is it fuel or my spark?.it has an edelbrock carb new fuel pump line & filter. origanal points distributor(new points),would changing that out for an HEI unit make a difference?thanks.Karl

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    Last edited: Mar 16, 2011
  2. dvalentine

    dvalentine Charter Member

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    "would changing that out for an HEI unit make a difference"

    Most likely yes, and in a positive way. No more points !

    You said that it did the same thing even after switching carbs. Based on that, check the vacuum advance module on the distributor, or just replace it...

    DVal
     
  3. 74X4Burb

    74X4Burb Member

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    I changed th dis. to a different points distributor with knew points but it dident change a thing.theres still a hesatation and the secondaries dont work. now what.this thing is driving me crazy.theres alot of potential in this ol horse I just dont know how to get it.Thanks.Karl

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    Last edited: Mar 16, 2011
  4. dvalentine

    dvalentine Charter Member

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    Is the vacuum advance line going to the correct port on the carb ?

    DV
     
  5. 74X4Burb

    74X4Burb Member

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    Good question.I'll let you know when I get a knew water pump on it.thanks.Karl;-)

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    Last edited: Mar 16, 2011
  6. 74X4Burb

    74X4Burb Member

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    I got the truck back together dident change a thing switching vacum ports though. I did put that carb on my suburban and it ran like a top.Karl

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    Last edited: Mar 16, 2011
  7. MY 57 CHEVY

    MY 57 CHEVY Guest

    Check the The weights in the dist. they may be stuck.
     
  8. 56bassman

    56bassman Member

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    Ok. Since you changed the carb to another vehicle and it ran ok its probably not the problem. First thing I would do is take a look at the spark plugs to "read" them. Also what kind of condition are your plug and coil wires in? Is the carb vent being blocked from the lid being turned upside down or a aftermarket lid thats too close? Last thing could be a weak coil crappin out under load. hope this helps. Ed
     
  9. 74X4Burb

    74X4Burb Member

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    My spark plugs are that nice light brown color.spark pug wires are new.put a new coil in but dident help.could it be a battery cable? I havent checked those latley. or maybe my transmission?.Thanks Karl

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    Last edited: Mar 16, 2011
  10. 74sbc

    74sbc Member

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    [updated:LAST EDITED ON Jul-08-05 AT 08:45 PM (CST)]check your alternator and alternator belt, your alternator belt may be bad and start to slip when you get too much torque behind it.
     
  11. Headwind

    Headwind Member

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    You said you put a new Edelbrock carb on it? You need to change
    the jets in the carb.
     
  12. 74sbc

    74sbc Member

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    [updated:LAST EDITED ON Jul-16-05 AT 02:15 AM (CST)]my friend had a truck that has the same problem, it was the PCV valve, he ripped out all that emissions crap and it runs beautifully now. :+ it only did it when he got to like 3 grand on the tach, then it would jerk like hell
     
  13. 74sbc

    74sbc Member

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    >my friend had a truck that has the same problem, it was the
    >PCV valve, he ripped out all that emissions crap and it runs
    >beautifully now. :+ it only did it when he got to like 3
    >grand on the tach, then it would jerk like hell





    ............Sorry meant EGR valve!
     
  14. Headwind

    Headwind Member

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    If the carb worked good when you tried it on a different engine & you have gone through all the other suggestions made it seems that perhaps the fuel pump pressure should be checked. If pressure drops below 2.0 psi you may need a pump with more capacity. That would explain why your truck has always had this problem no matter what carb is on it........
     
  15. Headwind

    Headwind Member

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    It shouldn't drop below 2.0 psi when the engine is running at high rpm or with the throttle wide open.
     
  16. 74X4Burb

    74X4Burb Member

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    put HEI on it dident change nothin.should I go with smaller or bigger jets in the carb?.I have changed the fuel pump twice with no results.should I try a stronger alternator? how do I switch over to the new style alternator?.Thanks.Karl

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    Last edited: Mar 16, 2011
  17. dvalentine

    dvalentine Charter Member

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    Karl, Have you set the distributor timing properly ?

    DV
     
  18. 74X4Burb

    74X4Burb Member

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    set it with a vacumm gauge and a light. its at about 15 BTC.Karl

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    Last edited: Mar 16, 2011
  19. Shane_68C10

    Shane_68C10 Member

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    Its your intake, its probably a single plane made for high rpm applications like a racecar, put an edelbrock torker II or Performer on it unless you already have one
     

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