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Thread: gassy carbs

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    Jedi Warrior Sopwith_Camel's Avatar
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    Lightbulb gassy carbs

    well I'm close the carbs SUs type HIF4s are idling high. but I'm not stalling out.
    today it was warm enough I could get the choke off yes its 49 degrees in mid norway.
    I have the jet adjustment screws about two turns down.
    the issue is Im bogging down on the test drive when I give its some "welly" at about 2500rpm
    Question so less gas with the idle screws or with the needle jets adjuster?

    tomorrow is to be 4c so I have another shot at this, but only 4.5 hours of day light. I do need to get the power on to get up the hill to the house.
    its a sobering thought that when Motzart was my age he had been dead for 12 years.
    Shaggy 70 Spridget
    Kitty 67 Jag MK2
    Folly 70 MGB-GT
    welly 95 Jag XJ

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    Yoda PAUL161's Avatar
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    Re: gassy carbs

    Two things to think about, make sure the dampers have oil in them and make sure the floats are not set too high. Are the butterfly discs opening equally, meaning one is not leading or lagging the other? Are your air cleaners original, are they clean? Some after market air cleaners are too restrictive and can cause a rich mixture, if you have after market air cleaners in your situation the best way to check is to take them off and run the engine without them for a test. Just throwing a few things your way, maybe one will help. PJ

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    Jedi Warrior Sopwith_Camel's Avatar
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    Re: gassy carbs

    Ill check the oil again first thing tomarrow. sun rise 10:02.
    but the air filters are off while I'm working on it.
    its a sobering thought that when Motzart was my age he had been dead for 12 years.
    Shaggy 70 Spridget
    Kitty 67 Jag MK2
    Folly 70 MGB-GT
    welly 95 Jag XJ

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    Jedi Knight
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    Re: gassy carbs

    I may have missed a earlier post about this car but I would start at the distributor. Be sure the mechanical advance is not seized. Have timing set at 32 degrees before top dead center at 3000 rpm with vacuum disconnected and then mess with the carbs. If you think its lean then pull the choke out as you are about to hit 2500 rpm ( your bogging point ) and see what happens with a richer mixture. Good luck getting the little car running proper!

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    Jedi Warrior Sopwith_Camel's Avatar
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    Re: gassy carbs

    the vacuum advance has is ok, no the issue is with the carbs, I rebuilt them last year and just haven gotten them tuned up right.
    it was running ok today but still not giving me power when I put my foot in it.
    Im going to run out of warm weather soon.
    steve
    its a sobering thought that when Motzart was my age he had been dead for 12 years.
    Shaggy 70 Spridget
    Kitty 67 Jag MK2
    Folly 70 MGB-GT
    welly 95 Jag XJ

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    Freshman Member Gokart's Avatar
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    Re: gassy carbs

    Do you know of a garage locally that has a CO2 exhaust meter and (and a rolling road is handy). If you can find one and they can spend a little time fine tuning your car for not too much of a cost, that would give you a better idea of how close you were and what they did to bring things to optimum.

    I did this. It took the garage 1/2 an hour and cost me $50. They said I was pretty close and it was only a bit of fine tuning to get it right. But having that sort of diagnostic equipement makes it a lot easier. They had the car running at 3000 rpm on the rolling road to get the optimum flow and were checking the timing at the same time.

    I had followed the SU tuning instructions prior to the garage fine tuning. I used my ears and tube for the air flow rather than a flow meter.

    If the carbs smell gassy that usually indicates the mixture is rich, which is a common MGB/SU tuning fault/problem.

    I have to wonder with the exceptionally cold conditions if the weight of the oil in the pots may be too thick from being colder than optimum.
    Cheers Rob

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    Freshman Member Gokart's Avatar
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    Re: gassy carbs

    Sorry, just noticed that the thread was from last year. New here and was looking back on some threads.

    Did you get your car tuned properly?
    Cheers Rob

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