Idle Speed / Tap Throttle Back to Idle

[bigboi]

So I have been messing with my carb again. I just keep trying to make adjustments to "get it right".

Here is what is happening...

I am idling around 850-900. When I tap the throttle when in neutral to rev the engine it takes a while to drop back down to 850-900rpm. When I say it takes a while, it takes longer than it should. Before I used to blip the throttle to rev the engine while in neutral and the idle would come right back down to 850-900rpm fairly quickly.



Does anybody know what I need to look at from an adjustment standpoint to remedy this issue?

Another thing... I was reading. If the car is idling and I manually shoot the front pump shot and the cars RPM goes up and then gradually back down I am running too lean. I read that if I manually bump the front pump shot and the engine stumbles I am right on the money. Well... I can't get it right on the money.

Anyhow... I am rambling. Any suggestions as to what to adjust next to get the idle to come back down quickly after I tap the throttle to rev the engine while in neutral let me know.

Thanks,
Brian

[DCx]

is it a demon? my demons idle will stick after a drive around the block or a rap of the throttle. its irratating when your car is stuck at 1200. i can get out of the car and press on the linkage and she returns to 900.

i have been over the demon so many times it makes me sick. i even took it to the carb shop who went through it as well.

needless to say a new holley is in the mail.

[bigboi]

It was actually a vacuum leak in the intake manifold gasket. I couldn't figure it out so I slapped a new set of gaskets on and waaalaaa! Problem fixed. Sometimes it's the simple things.

Brian

[Shaker455]

Hanging in there Brian?

[Tech @ BG]

It was actually a vacuum leak in the intake manifold gasket. I couldn't figure it out so I slapped a new set of gaskets on and waaalaaa! Problem fixed. Sometimes it's the simple things.

Brian

Thats good to hear. It's funny how the carb always gets blamed for everything when often it is something else that was causing it like in your situation. Glad you got it correctred.

In regards to the other poster looks like the new Holley has a similar issue as the Demon did so maybe in his case it wasn't a carb issue afterall.Here is his posting from the Camaro board about the new carb.
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MY FIRST 69
Senior Tech


Join Date: Feb 2000
Location: San Bernardino, CA
Posts: 1,174



i still notice a slight increase in rpm after the car reaches operating temp and is revved up pretty good.

hood space is limited with my stock cowl hood. i need to cut the bracing around the stock opening so i can fit my 14'' air cleaner on there. the ls1 sits a bit more forward than a stock sbc, i used a popular setup to mount it and i think it fit great.

im yet to jet down the carb.
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[6'9"Witha69]

My very first instinct was vacuum. Not much else other than a sticky main shaft and inadequate return spring will cause the condition noted by the OP.

[Tech @ BG]

Butterfly position and idle mixture screw location can also have an effect on it.