Idle speed increase - 440 w/4 bbl and 4 spd

[paladin06]

I noted while driving to a crusie in on Friday night, that once the car gets warn, the idle increases about 500 to 600 RPM. The car has a Dominator carburator on it. Any ideas why?

 

[krowbar]

You don't have a choke so its running rich when cold to keep it from stalling. Then it warms up and smooths out.

 

[paladin06]

Then do I just need to adjust the idle speed?

You don't have a choke so its running rich when cold to keep it from stalling. Then it warms up and smooths out.

 

[krowbar]

I have a holley 850 with choke so plate removed. I start it and have to keep it running for a couple minutes. Then it idle at about 650rpm after it warms up about 850rpm. When I drop it in gear back to about 650-700rpm. Mines lopey with the purple cam and sounds mean at that idle speed in gear.

 

[paladin06]

My problem is very similiar to yours. Once I engage the clutch the idle backs off. Perhaps it's not a problem. I know nothiing about Dominator carbs. Perhaps I need to educate myself.

I have a holley 850 with choke so plate removed. I start it and have to keep it running for a couple minutes. Then it idle at about 650rpm after it warms up about 850rpm. When I drop it in gear back to about 650-700rpm. Mines lopey with the purple cam and sounds mean at that idle speed in gear.

 

[krowbar]

My problem is very similiar to yours. Once I engage the clutch the idle backs off. Perhaps it's not a problem. I know nothiing about Dominator carbs. Perhaps I need to educate myself.

If you're running a standard I would just adjust the idle down,but you will have to keep it running until it warms up a bit and idles on it's own. No choke is sometimes a pain...

 

[cwhubb]

I noticed the same thing with my 950hp once it warmed up I had to turn the idle down, as a side note my 950 wont idle without me stepping on the gas or holding the throttle open a litte, just one of those trade off things

 

[Garys1969RR]

My Holley 780 does the same thing. Idles a lot faster warmed up than cold. And I am not running a choke. One thing to be sure and check is that you have to plug off the choke vacumn port on the carb after you remove the choke mechanism. That actuates the choke pull off. I didn't plug mine, and it had a vacumn leak. Had a flat spot at off idle, and wouldn't idle right. Made a big difference after plugging it.

 

[krowbar]

I had to put a new baseplate on mine because it was sucking air past the throttle shafts.

 

[paladin06]

Yep, it's plugged.

My Holley 780 does the same thing. Idles a lot faster warmed up than cold. And I am not running a choke. One thing to be sure and check is that you have to plug off the choke vacumn port on the carb after you remove the choke mechanism. That actuates the choke pull off. I didn't plug mine, and it had a vacumn leak. Had a flat spot at off idle, and wouldn't idle right. Made a big difference after plugging it.

 

[paladin06]

I got a digital timing light today and looks like the car is at 8 degrees advance and 746 RPM idle speed.

I did have to adjust the level in the forward bowl. It was way to high. It was about about at the 3/4 mark on the glass. The aft bowl level was just below the 1/2 mark. I have not yet checked the idle mixture. Your thoughts.

 

[krowbar]

Its a good idea to get everything adjusted right first. 8 deg sounds a little low.? Is the motor stock? adjust the floats and idle mix to most vacuum you can get. Then check idle speed and timing.

 

[paladin06]

The motor has been rebuilt, 30 over and I believe the cam is stock if not it may be a little over stock. The shop manual I have says the timing should be 7.5 degrees, is that incorrect. Also the car still has the points ignition system.

Its a good idea to get everything adjusted right first. 8 deg sounds a little low.? Is the motor stock? adjust the floats and idle mix to most vacuum you can get. Then check idle speed and timing.

 

[krowbar]

You can try bumping the timing up a little. If its running good I wouldn't mess with it though. The only reason I would bump it up would be the quality of todays fuel. Make sure you check the dwell and point gap too. I did away with the points in all my older vehicles. If all you're concerned with is the idle fluctuating......you might have to live with it like that, or get a carb with a choke.

 

[paladin06]

I have experienced an occassional back fire through the carb.

 

[Funship32]

Just for giggles I'd make sure your intake bolts are cinched down. Sounds like once it warms up, you may be getting a vacuum leak which would cause some of your issues.

 

[paladin06]

Hummm, I did not check that but I will.

Thanks

Just for giggles I'd make sure your intake bolts are cinched down. Sounds like once it warms up, you may be getting a vacuum leak which would cause some of your issues.

 

[paladin06]

OK, adjusted idle mixture, none of the four screws where the same. Adjusted the timing and idle and she sounds great. The throttle response is awesome. She sounds so much stronger.