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Thread: Cold starts on carbs with no choke

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    Mechanic beeRS's Avatar

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    Cold starts on carbs with no choke

    What is it supposed to be like starting a twin carb engine from cold where no choke is fitted?

    I've just fitted twin IDF's to my Pinto and when starting from cold it cannot hold an idle and misfires intermittently from all 4 cylinders for the first couple of minutes. Once its warm it run fine.

    Is this to be expected?

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    Re: Cold starts on carbs with no choke

    yes

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    Bodger capri dave's Avatar

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    Re: Cold starts on carbs with no choke

    ive run weber 45 dcoe carbs on a daily use road car in the coldest months of winter.

    2 pumps of the accelerator pedal before firing up, and just keep her tickled for the first couple of miles...

    you wont have a reliable tick over for a couple of miles, and you may hear a bit of spit back from the inlet trumpets.
    Last edited by capri dave; 12-06-2016 at 14:46.
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    World Champion Decade Plus User meXEco's Avatar

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    Re: Cold starts on carbs with no choke

    Same as above, few pumps on throttle then just keep her going for a few minutes then good to go.


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    Spanner Monkey

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    Re: Cold starts on carbs with no choke

    What idle jets you using BeeRS.
    My Engine is fairly mild and after set-up by RR I checked and saw the only jets they never changed was the idles which are 55's
    Starts first time and ticks over at a steady speed hot or cold.

    Is it set-up correctly?

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    Mechanic beeRS's Avatar

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    Re: Cold starts on carbs with no choke

    Hi Again Yellowtaxi,

    Indeed you were right to be suspicious about the idle jets. My engine builder dyno'd the engine (out of the car) with the Weber's fitted. I thought what I got was a sorted package. That was January this year. With the engine in the car I've now had it set up again on a rolling road and the only jets they changed was the idle ones. Not sure what size they used, but the car starts much better now. Almost idles good straight from cold!

    Its funny how one guy's idea of a 'set up' engine is different to another's. The dyno guy says the only proper way to set up an engine is on the dyno. The Rolling Road guy says that the rolling road is best.

    Anyway - its running well now. 177bhp at the flywheel and 155 at the wheels. Pleased with that.

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