idle fluctuations

[Zooted_plus]

When idling at a stop light for any period of time, sometimes my idle starts to fluctuate from about 650 to 750/800, then back down. It gets to the point where the engine wants to die. How do I get it smoothed out? play around with the mixture screws?

 

[6Stang7]

Is it only when you sit idling?

-Shaun

 

[68GEETEE]

have you checked for a vacuum leak at the manifold?

 

[hummer784]

My car also does somethign like that, but i know i dont have any manifold leaks. What gives?

 

[6Stang7]

There could be a couple things going on, but I would need to know when it happens. What the conditions are, what the engine temp is, stuff like that.

-Shaun

 

[SandSprite]

try the idle mixture screws and look/listen for a leak.

 

[Zooted_plus]

Its only when I'm idling, re adjusted the mixture screws today, made sure they are turned out an equal # of turns on each side. Still fluctuating. The other problem I'm having is with my coolant temp gauge... so I don't even know what kind of water temp I'm running at the moment.

 

[6Stang7]

Well, does this only happen when the engine has been running for awhile?

-Shaun

 

[Zooted_plus]

yes, doesnt happen when cold... only after its been warmed up.

 

[K:^P]

I'm thinking the idle mixture is running too lean

 

[geegee]

When idling at a stop light for any period of time, sometimes my idle starts to fluctuate from about 650 to 750/800, then back down. It gets to the point where the engine wants to die. How do I get it smoothed out? play around with the mixture screws?

Make absolutely sure your Holley float levels are set correctly at the bottom of the sight glass/port. Start with low float level and move up to the sight glass/port. You'll need a vaccuum guage or a tach/dwell unit to adjust the mixtures. Idle down then close mixtures evenly until the engine starts leaning out. Reverse direction on the idle mixtures (open) until rpm just tops out and no more, else until engine vacuum increases and just tops out and no more.

When opening or closing mixtures, know how many turns each is open. The end result is to have the mixtures just at max rpm/max vaccuum and equally open.