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Engine won't run smoothly at 2000rpm

Discussion in '40- & 55-Series Tech' started by FJAfrica, Oct 31, 2003.

  1. FJAfrica

    FJAfrica

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    OK, I know this type of topic has been covered, but I have searched the forum, and have not quite found my answer. :ban:

    Problem:
    I have just rebuilt my F engine, new rings, valves done, etc. Compression is now good, and all the leaks appear fixed. I still run stock points in a NON-USA dizzy, and have a NON-USA Aisin carb. I have set the valve clearances to spec when warm. The problem is that when the engine runs at about 1500 - 2500rpm, there is a terrible misfire, more noticable when the engine is not loaded, going up a hill it gets better when you apply more gas.

    There is a hesistation when pulling away from a stop sign. I cannot pull away from idle, the engine dies, I first have to get the engine above 1500 and then let out the clutch.

    My queries:
    Ignition system is newish, but tends to burn the points quite quickly. I will be checking the dwell angle on the weekend, but my question is, apart from the point gap, how else would one adjust the dwell angle? I have repeatedly set the timing, but the points keep burning after 1000 miles. What should the dwell be, 41 ? At what engine rpm should one check the timing, the figure varies from 650 - 950 depending on which forum you look ???

    If I look down the carb while applying the gas, the accelerator pump jet appears to be working, as a seemingly healthy dose of fuel is pumped into the manifold. When adjusting the idle mixture screw, it appears to have no affect on the engine. Could this problem be with the carb? I am at sea level, what are the correct jets to use?
    I have put new manifold gaskets on, and there does not appear to be any leaks. I can't feel any significant play on the dizzy shaft either.

    Anyone got some answers :'(
     
  2. hammerhead

    hammerhead

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    Burnt points usually mean bad condenser. Mixture screws should effect running. Does your carb have fuel cutoff solenoid valve and is it working?
     
  3. FJAfrica

    FJAfrica

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    I'll replace the condenser and see. Yes it does have the idle solenoid, and it seems to be working OK. If I disconnect it, the engine dies.
     
  4. theo

    theo

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    Also, point gap and dwell angle are mutually dependent. No way to change one without changing the other so you're doing it right.

    Not sure on jetting, but even if the jets are a little off it should run better than it is. What about checking the mechanical and vacuum advance?
     
  5. Degnol

    Degnol

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    Do you have a ballast resistor? The voltage to the Dizz should be something less than 12v except when starting. There is a wire that comes off the starter and bypasses the ballast resistor just for starting. If you are running w/o a ballast resistor, that is more than likely what is burning your points. If you are using the non-USA dizz, are you sure that the timing specs are the same? Do you have the vacuum advance hooked up to the port on the carb?
    Just some thoughts.
    GL
    Ed :) :)
     
  6. IDave

    IDave

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    I would bet on a point gap/timing issue. I have the same dizzy/carb setup. I think the point gap is a bitch to get just right sometimes.
     
  7. landcruiser

    landcruiser

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    My vote is a carburation problem. Sounds like you ae running lean. That could be caused by a faulty carb or possibly a vacuum leak, and I'll bet it runs better with the choke partially closed.
     
  8. rwlc63

    rwlc63

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    i had same problem it was a intake leak i found by running the eng. and spraying
    carb cleaner on vac lines and intake gasket and listen for rpm change.
     
  9. FJAfrica

    FJAfrica

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    A few answers:
    Yes, I do run the ballast resistor, 9V at the coil for running, 12v for starting.

    The vacuum advance appears to work fine, the timing adjustment screw at the base of the dizzy moves in/out freely when one revs the motor.

    I have just bought new points & condensor, today I will revamp the complete ignition system.

    Thanks for the tips so far, I will keep you guys posted.