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I recently installed my first Holley, an 1848, 465 cfm vacuum secondary, with the hot air choke. I'm now learning the Holley.
It is on a pepped up 300 inline with the hp of a 360 with a 2v carb.
I am posting because of an issue that has me stumped. It starts and idles fine, but after driving a bit when I come to a light the idle drops lower and it starts to chug, as if it is going to stall. It has an auto trans. If I shift into N or P it runs smooth, but slower rpm than set. I should mention the carb was NOS, and had set on a shelf for untold years, with paper gaskets. I went through it and put in a kit.
I have had issues with header heat causing fuel boil/vapor lock and am getting ready to change header--which is right under the carb/intake--to efi manifolds. Does this sound like a heat issue? or possibly a foreign body in the idle circuit?
Hard to say. One thing I found that makes these things easy to figure out is a wide band air/fuel ratio meter. I got one from summit, wired it to a cig lighter plug and use it for diagnosis stuff. It requires installing a port in the exhaust for the o2 sensor. The benefit is knowing if it lean or rich and when instantly. Then you know what to fix.
I would look at float level and vacuum leaks. Holleys tend to have less problems with heat but thats on V8s. I suppose it could be heat related.
Autolites on automatic trans-equipped vehicles had a deceleration valve which prevented the carb from slamming shut when ya let off the pedal. I think that principle might be amiss on that Holley.
Have you adjusted the primary floats? Sounding like they might be a touch high. How did you adjust the mixture?
Hello, yes, I adjusted both float levels and set the mix with a v.gauge.
HioSilver: Yeah, I remember that valve in front of the throttle linkage on the 4100's. You may be right about this Holley needing one.
Guys, the problem may be that I have an open vacuum port for the hot air choke. How should address that issue? Does anyone run a hot air or thermostatic choke? Thanks.