Carter AFB - 3721S - or is it?

[Mark H.]

II recently purchased a Carter carb for my ’64 L75. I thought I purchased the right unit, but now see the following discrepancies. There is no date code. Each foot has 2 mounting holes (rather than 2 singles and 2 doubles). The casting number on the body is 0-1523; the air horn casting number is 6-1585. The choke does not have the air fitting in the center of the cover, it is at the 5:00 position under the cover. The cover says “Carter Climatic Control” and bears the number 175 X4785. The port for the vacuum advance tube is outboard of the passenger side idle mixture screw. There is also what looks like a name plate riveted to the front of the curved part of the air horn (if you look at the front of the carb it would look right back at you), but it doesn’t say anything. The linkages also do not appear correct, and the brass “things” that stick out into the barrels of the carb do not look like they stick out as far as the ones in the manuals I have.

Can anyone help me identify what I’ve got here? My car is a driver; I am trying to get it back to stock configuration or close to it. The unit generally looks clean and in good shape. I’d like to salvage it if I can. Opinions? If it becomes a paperweight, that’s OK too.

[Duke W.]

Re: Carter AFB - 3721S - or is it?

What makes you think its a 3721S? If it has the triangular metal tag attached to a bowl cover screw that says 3721S, it doesn't mean much.

The Carter number and date code should be stamped on the main body mounting flange right side front face, above the date code, but if the date code is gone the Carter number is probably gone, too. Does that surface look like it's been filed?

Since AFBs are a family that are made up from a variety of standard parts it's pretty easy to build a mongrel, and I bet a lot of the old AFBs left out there are far from their original configuration.

Duke

[Mark H.]

Re: Carter AFB - 3721S - or is it?

3721S is stamped on the main body mounting flange in the place you describe (right, or passenger side, front face)but there is no date code.

[William C.]

Re: Carter AFB - 3721S - or is it?

Pontiac carbs were not stamped and used the choke mechanism you describe. I smell something. What does the throttle linkage arm look like?