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What could cause fast idle when hot?

2355 Views 5 Replies 3 Participants Last post by  Andrew
My "new" 74 GTV idles around 1000 rpm when I first start it. Once it has been running a couple of minutes the idle speed is around 1500 rpm. The engine has 40 dcoe 138 carbs, electronic ignition (RML ARPI 4101 R) C&B 47 cams.
Any suggestions on where to start looking would be appreciated.

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Check and make sure that your dist advance is not advancing. Usually, timing is at 700-800 rpm with 4 deg... If you know what your max advance is set that and work back. I would also set Idle at 800 rpm. You will also be a little lean when the engine is not at running temp, this will cause a slight change in idle as well. Good luck...
Thanks for the suggestions. I have to take the linkage apart to see if I can get it to idle any slower. Right now, the idle speed screw is all the way out.
My battery is in the trunk, does it make any difference where I get the power for the timing light?
Function and adjustment of the TA can also affect idle speed, hot and cold.
Andrew, I'm running Webers.
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