Automatic choke setup
Thread Starter
Burning Brakes
Joined: Aug 2002
Posts: 1,145
Likes: 0
From: Texas
St. Jude Donor '09
Automatic choke setup
started 64 327/300 -4speed first time today since putting it away for the winter.
Had to take automatic choke apart as it was froze up and non-functional. Book says to set it at 1 lean. Where is 1 lean. Is it from the extreme setting on the left-? or right from the benchmark? or is it from the center benchmark -1 mark left or right. Help- Thanks Jimbo :cheers:
Had to take automatic choke apart as it was froze up and non-functional. Book says to set it at 1 lean. Where is 1 lean. Is it from the extreme setting on the left-? or right from the benchmark? or is it from the center benchmark -1 mark left or right. Help- Thanks Jimbo :cheers:
Melting Slicks
Joined: Dec 1999
Posts: 2,489
Likes: 32
From: New Smyrna Beach FL
Re: Automatic choke setup (Jimbo64)
1 lean is one mark off center in the direction in which the choke plate opens. I think your choke opens toward the firewall. So , one lean is left toward the firewall.
Safety Car
Joined: Feb 1999
Posts: 3,631
Likes: 14
From: Fountain Hills AZ
Re: Automatic choke setup (Jimbo64)
Don't be afraid to deviate some from the factory specs if you need to but they're as good a place to start as any. Over time and use, it's not unusual for resistance to opening to increase or decrease so factory specs may not be the best in your particular case. The factory specs were also a compromise to work adequately in all climates so some climates might make a adjustment desirable.
Melting Slicks
Joined: Oct 2001
Posts: 3,025
Likes: 12
From: Pleasant Grove AL
Re: Automatic choke setup (Jimbo64)
Unless you live in a very cold climate, adjust the choke to open as soon as the engine starts and will run without it. That real rich mixture is BAD for your engine.
Race Director
Joined: May 2000
Posts: 12,712
Likes: 2,271
Re: Automatic choke setup (Jimbo64)
Look for the word "lean" and an arrow on the choke housing to establish the reference direction. Setting the choke lean from the "index" (the big hash mark between the small ones) will mean less spring torque to close the choke valve.
The choke has a vacuum break that opens the valve about half way once the engine starts and develops some manifold vacuum. That's what the piston in the choke housing is for, and a gummy piston is probably the most common AFB malady.
You can remove the choke housing to disassemble and clean it up without removing the carb. Also be sure that the choke clean air heater tube though the manifold has not burned through, which will allow exhaust gas into the choke housing and foul it up in no time flat.
When you reinstall the choke housing to the main body, be sure you have a new small o-ring to seal the choke vacuum break passage.
It's my gut level feeling that the thermostatic springs loose tension with thermal cycling, so you might actually have to set it a notch rich to get proper choke valve operation. The choke valve should fully close at room temperature with the throttle lever off the idle stop. Check your choke linkage dimensions to be sure they are in spec.
The AFB is the simplest and most reliable four-barrel carburetor on the planet!!!
Duke
The choke has a vacuum break that opens the valve about half way once the engine starts and develops some manifold vacuum. That's what the piston in the choke housing is for, and a gummy piston is probably the most common AFB malady.
You can remove the choke housing to disassemble and clean it up without removing the carb. Also be sure that the choke clean air heater tube though the manifold has not burned through, which will allow exhaust gas into the choke housing and foul it up in no time flat.
When you reinstall the choke housing to the main body, be sure you have a new small o-ring to seal the choke vacuum break passage.
It's my gut level feeling that the thermostatic springs loose tension with thermal cycling, so you might actually have to set it a notch rich to get proper choke valve operation. The choke valve should fully close at room temperature with the throttle lever off the idle stop. Check your choke linkage dimensions to be sure they are in spec.
The AFB is the simplest and most reliable four-barrel carburetor on the planet!!!
Duke
Thread Starter
Burning Brakes
Joined: Aug 2002
Posts: 1,145
Likes: 0
From: Texas
St. Jude Donor '09
Re: Automatic choke setup (Jimbo64)
Thanks guys for the quick response, we'll give it a whirl and maybe she'll start working the way it was designed to.. Again thanks for the help. Jimbo
:cheers: :seeya
:cheers: :seeya
