Carter AFB - Choke Spring

[bcomo]

I just rebuilt my 60 Carter AFB. Everything works great except for the thermostat choke spring. It doesn't release enough to allow the butterfly to go fully open. Everything in the choke housing is functioning fine, including the vacume piston.

My question is -- does anyone know of a source for either a new choke spring, or if I have to, a complete new choke assembly? I don't want to convert to electric choke -- and electric is all that I see listed on the web for Carter AFBs.

[6TB1RD]

Adjustment ?

Bart:

On the out side edge of the choke cover you will see what looks like a little triangle; this is the arrow that you use on the scale on the frame of the choke mount. Turn it left for lean and right for rich. Loosen the 3 retaining screws (do not remove them) and turn the cover either right or left to open the butterfly valve.

If this does not work you might have the spring on the wrong clip inside the housing (this is what was wrong with mine it slipped off when I was reassembling the choke ) it's not hard to make this mistake, but try the adjustment before you take it apart again.

Don't for get to retighten the 3 screws.

[Alexander]

Those bimetallic coil choke springs get mis-shappen with use, so it may not work properly. There is a lot of interchange with those springs. You should be able to get a new one.

[bcomo]

6TB1RD:

Thanks for that advice. Been there - done that -- over and over. The problem is with the spring itself. I've removed the choke completely, and assembled it correctly, but the spring is too old.

Alexander:

Correct -- the spring is shot. You would think that I could find a new spring, but so far I haven't. I sent 4 E-Mails asking to find one, so maybe I'll get an answer soon. I'll follow up with a post.

[byersmtrco]

Try Chrylsler. More Mopars used AFB's than Ford's. Most of the mid-late 60's and some early 70's 383's & 440's had AFB's on them. They prob had the same choke stat as the AFB used on the 430.

[bcomo]

John:

Thanks for that information on the Mopar choke. Good to know if I need some other parts for the AFB.

I found a choke spring at Daytona Carbs in FL (386-427-7108) for $5 Part #61-166. It fits all Carter AFB hot air chokes.

I spoke to a guy there named Ron who spent 1/2 hour on the phone with me telling me all about how hot air chokes work. There's alot more to how it works besides the spring.

Everyone knows that the choke gets hot air from the small exhaust manifold pipe to heat the choke spring. That heat relaxes the spring. That tube has to be clear inside -- no obstruction, or the spring will not heat up to the temperature it needs to relax (unwind). I checked mine using a large diameter guitar steel string -- very flexible. It was OK.

After the spring relaxes, what actually opens the choke is a small vacume piston, inside of the choke, that gets manifold vacume from the back side of the choke. The piston has to move freely. It can be taken apart and cleaned. Mine was OK.

There is a rubber grommet in back of the choke that seals to the carb where it gets the vacume. Bad seal, bad vacume, no open choke. Mine was fine.

So, there are really 4 things to look at: The spring, the exhaust manifold heat pipe, the vacume piston, and the vacume seal grommet.

I wonder -- who thought that gizmo up?

[byersmtrco]

The Edelbrock "Carter AFB" the I have on there has an elec choke. It really works great.

[bcomo]

Yes, the electric choke kit is available separately as a conversion for the Carter AFB. If the spring that I'm getting doesn't fix it, then I might go with the electric choke.

[bcomo]

I solved the choke spring problem. It seems that the older the hot air choke spring gets, the more manifold heat it takes to unwind the spring.

If you remove the choke cover, you'll see a loose metal plate between the cover and the choke pull-off link inside the choke. It dissapates some of the heat coming in to the choke from the manifold.

I removed that plate, and reassembled the choke without it. The choke spring now gets more heat, and works perfectly. Happy ending.