Carb tuning
Thread Starter
|
Laughing Gas
Joined: Aug 2010
Posts: 1,049
Likes: 230
From: Amarillo, TX
Carb tuning
I've got a 60 F250 with a 292 & holley 2300 2 barrel carb. It has been running fine, but lately, as the weather has turned colder, it won't idle or run at low rpm's without the choke on. All the trucks I've worked on to this point have been fuel injected, so I know very little about carb tuning; could someone offer any suggestions?
Hotshot
Joined: Oct 2009
Posts: 16,192
Likes: 4,801
From: Burbank, WA
That sounds about normal, to me. Carbs with manual chokes typically need to have the choke closed a bit to start it and keep running before the engine warms up to normal operating temperature. In colder weather, it takes a little more choke to keep it running and takes a little longer to warm up good before you can open it again fully, which means pushing the **** in all the way to the dash. With fuel injection, the computer does all this automatically and provides the exact amount of air and fuel to work at the exact optimum settings. Fifty years ago, when your truck was new, it was up to you to do the work of a $20,000 computer today.
Logistics Pro
Joined: Oct 2002
Posts: 4,489
Likes: 5
From: Valley Center, CA
Have you tried adjusting the idle mix screws on the back of the carb? Once the engine is warmed up, you can try turning in one screw while the engine is idleing. When you hear the rpms start to drop, turn it back out about 1/4 turn. Then repeat on the other screw. Al ittle richer may help in colder weather. 
Also, you may need to set the idle up just a little. Most carbs have a small cam on the choke arm that raises the idle when the choke is applied. Jag
Also, you may need to set the idle up just a little. Most carbs have a small cam on the choke arm that raises the idle when the choke is applied. Jag
Post Fiend
Joined: May 2008
Posts: 7,641
Likes: 21
From: Poway, Ca.
Idle mixture is pretty temperature dependent especially if it was set in warm dry weather.
I would retime and reset the idle mixture with a vacuum gauge. Here's a link to ta thread with the procedure.
https://www.ford-trucks.com/forums/8...e-trouble.html post #2.
For a quick fix try backing the idle mixture screws out 1/2 turn from their present position.
I would retime and reset the idle mixture with a vacuum gauge. Here's a link to ta thread with the procedure.
https://www.ford-trucks.com/forums/8...e-trouble.html post #2.
For a quick fix try backing the idle mixture screws out 1/2 turn from their present position.
