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Holley 4 Barrell - High Idle

1435 Views 2 Replies 2 Participants Last post by  droptop85stang
Hello Everyone,

Sorry if this is a noob question.

My 85 has a stock holley 4 barrel. When I bought the car almost 2 months ago, it idled at 1000 rpm. It would occasionally have a sporadic idle between 700 to 1600 rpm or so, but it would not last long.

Lately, when I cold start the car it would idle around 1800 - 2000 rpm until the pedal is tapped once (it did that before which I think is normal). When the gas is tapped during the cold start the rpm's would drop down to 1000 rpm. However as the car warms up, the idle climbs up to 1500 to 1800 rpm and stay there even while driving. Between shifts, the idle would drop down to 1000, if I don't put the car into gear it climbs back up to 1500 to 1800 rpm while just coasting.

Unfortunately, I do not know too much about carburetors yet. Does anyone have any ideas or can someone recommend a good carburetor book. Well, I guess I'm assuming that it is the carb.

Thanks in advance!
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We don't do the "noob" thing here so don't worry about that.

What you describe sounds like a vacuum leak. The engine warms up, and the leak opens up. Use carb cleaner and spray around the gaskets around the carb and intake. You're listening for any change in how the engine is running. If it changes at all, then where the spray was is where the leak is.
Thanks EagleAutosports!

I'm not sure where to spray. I sort of tried that already. I used carb cleaner and sprayed all around the carb. I thought something might have been dirty or something. No change in the idle. When I sprayed carb cleaner in the carb (while the car was running), the idle would drop and then increase. When too much carb cleaner was sprayed in the carb the engine stopped.
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