How come my Holley carb's idle has to be kicked down manually when I put it in PARK? I can also push the throttle lever down myself to lower the idle. It idles at 1100-1300 RPM when put the tranny in PARK after driving. I then can kick it down to 750-800 RPM. I also can't adjust the idle any lower than 750. My Holley is a 4 barrel,600cfm, electric choke, 4160 Silver Series,universal carb,with Ford kickdown. It is bolted to a 305 H.O./Auto. Can a vacuum leak on the base cause a slightly high idle like a closed choke can even though that is rich, not lean like a vacuum leak? Thank You in advance.

 

It sounds to me that your fast idle isn't disengaging all the way.Is your choke working right?Mine has a fair bit of tension at the straight up and down/warmed-up position.If it is,you could try adjusting the fast idle cam under the choke assembly.My Holley gave me a problem with a fast idle,but it ended up being the secondaries set screw was holding the secondary blades open slightly.This doesn't sound like the same symptoms as mine had though.

 

Thank you for the information, MTCAMARO! I thouught the fast idle only worked when the choke was on. Then it drops to normal idle when the choke opens. I take it ,that the fast idle cam can affect normal temp idle too?

 

I'm far from a Holley expert,but i do know that if you have a weak electrical connection at the electric choke,sometimes it won't go to full open enough to stay off the fast idle cam.It will keep slipping in and out of fast idle like your's seems to do.I can tell you this from experience.The choke will warm up from engine heat enough to kind of look like it's working.I'd make sure the choke is getting a good, keyed 12 volt connection(At full warm,the choke should be straight up and down.if you try to pull it down slightly and let go,it should snap back to full open)If it is working,and the choke is just out of adjustment,you can try loosening the choke housing screws and adjusting the choke tighter buy rotating the housing.(mark the housing with a sharpie pen so you know where you started before you begin).If everything checks out,then you can look at adjusting your fast idle cam.I hope this helps you out.

 

Thank you so very much for your help! My choke is pretty tight,and the fast idle screw is at 1200rpm. The fast idle screw only kicks up the idle when the choke is closed. It kicks the idle down ehen the choke opens. Then again I'm not a Holley expert either.LOL I love this message board!

 

Your welcome Firechick.One more thing i thought of,and forgive me if this sounds kind of obvious, but do you have a stiff enough return spring hooked to your carb ?This could also cause your problem .I had to use 2 springs on an edelbrock carb that i used to run.One spring wasn't stiff enough to close the throttle blades all the way.

 

The hanging idle problem is going to be either a hanging up fast idle cam or insufficient return spring(s). Always run 2.

You should be able to lower the idle lower than 750. Back out the set screw on the secondaries, make sure they're closing. Make sure the screw is out on the primaries too. If it still won't go lower..it's a vacuum leak. Happy leak hunting