idle engine speed
05-18-2013, 03:11 PM
#1
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idle engine speed what are you guys idleing at? when hot, if i get her down to like 1000, i start to get a slight off idle stumble. thats with 22* at 1000 ramping to 32 at 3000 then flat from there. i would think im still to rich because if you touch the accelerator pump it bogs down. i dont have any idle air bleeds to play with only a few drilled throttle plates. just curious to see where you guys are at and where your timing is at an idle. thanks, paul
05-18-2013, 09:57 PM
#3
I had trouble getting my idle down to a reasonable speed and had issues with it stumbling a tad with slight throttle movements off idle. It was a real pain when cruising. Turns out I had the idle screw backed all the way out such that the butterflies were against the stops and not touching the screw at all. That caused too little of the transfer slot to be open resulting in stumbles off idle.
To fix this I set the idle speed screws so I had 20 thousands of the transfer slot visible in the primary and secondary, then dialed back the 500 RPM timing set point to adjust the idle speed down to 800 RPM. The car runs perfectly now. I can't remember the exact value I used at 500 RPM. But from 1000 RPM and up I have more normal values. I do run vac advance. I think I had to keep the static + vac advance under 20° to get the idle speed where I wanted it with the blades still open the right amount.
I think the reason my car idled so fast is I am running a stock LS2 cam that is pulling something like 23 inches of vacuum.
By the way, it is pretty easy to drill out air bleeds and tap them for set screws you drill yourself. That is what I had to do to get my transition circuits tuned right.
To fix this I set the idle speed screws so I had 20 thousands of the transfer slot visible in the primary and secondary, then dialed back the 500 RPM timing set point to adjust the idle speed down to 800 RPM. The car runs perfectly now. I can't remember the exact value I used at 500 RPM. But from 1000 RPM and up I have more normal values. I do run vac advance. I think I had to keep the static + vac advance under 20° to get the idle speed where I wanted it with the blades still open the right amount.
I think the reason my car idled so fast is I am running a stock LS2 cam that is pulling something like 23 inches of vacuum.
By the way, it is pretty easy to drill out air bleeds and tap them for set screws you drill yourself. That is what I had to do to get my transition circuits tuned right.
