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Old 05-17-2018, 07:51 PM
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dlloyd dlloyd is offline
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Join Date: Apr 2013
Location: Perry, Fl
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Quote:
Originally Posted by Dick Boneske View Post
If the choke is functioning properly, it should idle around 1700 rpm when first started (fast idle cam). When the engine is started and the choke pull-off sees engine vacuum, blipping the throttle should bring the idle down to about 900 rpm until the choke spring sees some engine heat from the choke heater tubes. Then, the idle should drop to whatever you have it set to with the idle stop screw. With a fairly mild cam on a 421, idle should be around 700 rpm.

It sounds like your choke may not be closing when the engine is cold, so idle mixture is a too lean. After the engine warms up, and can run on a leaner mixture than when cold, idle speed increases. I would expect this would also result in backfiring and poor throttle response when the engine is cold.

There may be a vacuum leak complicating the problem as well, but confirming whether you have an operational choke would be the first step in troubleshooting.
Dick, you really know your stuff!
You described exactly what is happening at start up.
I screwed up the choke setting by listening to a so called mechanic that told me I should set the choke wide open cold especially in the summer.
I am learning this stuff the hard way.
So tell me the proper way to set the choke.
While motor is cold do I adjust it fully closed?
Thanks so much for all you guys help!
I don’t know what I would do if not for all of you guys answering my questions.