Vintage Mustang Forums banner

1 - 7 of 7 Posts

·
Registered
Joined
·
13 Posts
Discussion Starter #1
With this car being my first carburetor engine vehicle, I finally found the sweet spot with cold starts. Tap on the gas pedal 3 times and start the car. The auto choke does its job. My fast RPM sits at 1,600. I give the gas pedal a tap after a minute and it idles at 900. I'm wondering if 1,600 is too high for the fast rpm. Any dangers with letting the car idle at 1,600 RPM for a minute or two?
 

·
Registered
Joined
·
4,855 Posts
leave well enough alone
 

·
Registered
Joined
·
9,029 Posts
Most of the pedestrian engines had a high idle RPM spec from 1200 ~1600. Some of the CJ/SCJ and Boss engines were upwards of 2400 rpm cold idle.

1600 should be fine. If it bothers you, lower it down a couple hundred rpms.
 

·
Registered
Joined
·
4,765 Posts
Fast Idle is a single screw adjustment on the screw riding the cam with the ^ showing the location of the screw on the cam at fast idle for Autolite 2100 and 4100 carbs. Might be opening a can of worms here, but if everything is operating as it should, that's all you should have to do to knock it down a bit. Shouldn't take much adjusting to do so.
737142
 

·
Registered
Joined
·
1,467 Posts
The Ford fast idle specs are in the back of the Fuel section of the shop manual.

It lists numbers anywhere from 1200-1900 depending on the application, so you're right in the middle. If you wanted to check exactly what it should be for your engine/transmission/carburetor combo though that'd be the place to check.
 
1 - 7 of 7 Posts
Top