3721SB Carburetor

[Kerry A.]

I have a 63 Cpe 327/300 built in May and the carburetor ID# is 3721SB. There is another stamping to the left and at the level as the ID# and it is G0. The G0 has me confused as I do not know what it represents. If it is a date code it would represent July 1960 which can't be. Also, according to the JG the model ID is 3721S and no SB is listed.

[William C.]

Re: 3721SB Carburetor

OK, I'm confused, the text says '63 Car, and 3721SB. The correct original carb is a 3461, for 1963, 3721 is a service carb (also oem in '64-65) What year abd carb are we trying to match here?

[Kerry A.]

Re: 3721SB Carburetor

I'm not trying to match anything. I have a 63 cpe with a 3721SB carb with another stamping that is G0. What is the G0 mean? It can't be July 1960. Also what is the SB mean? I have found 3721S and 3721SA and 3721SB. I'm aware the 63 327/300 carburetor is a 3461S but I'm trying to decipher the 3721SB stampings.

[William C.]

Re: 3721SB Carburetor

G0 likely 1970 date. SB was the last Service issue of the 3721, with the differences being minor jetting changes largely internal to the idle and low speed circuits. The 3721S (Later SA) was the Carter factory original ('64 up) and service replacement for all 3461 and 3721 carbs by 1968, with SB Suffixes in later years (over the counter or service)

[Kerry A.]

Re: 3721SB Carburetor

Thank you and that makes perfectly good sense. At least now I can establish a value for the carb.

[Jim D.]

Re: 3721SB Carburetor

G0 likely 1970 date. SB was the last Service issue of the 3721, with the differences being minor jetting changes largely internal to the idle and low speed circuits. The 3721S (Later SA) was the Carter factory original ('64 up) and service replacement for all 3461 and 3721 carbs by 1968, with SB Suffixes in later years (over the counter or service)

Are you saying that a 3721SB is a service replacement/over the counter carb.?

[William C.]

Re: 3721SB Carburetor

Given the date for this one, yes, I can't say for sure what the exact S/SA/SB change dates were, likely one of the carb restorers might have a handle on the changeover dates.

[Jim D.]

Re: 3721SB Carburetor

Thanks for the clarification. I misunderstood. I thought you were saying that all 3721SB's were replacement carbs.

[Kerry A.]

Re: 3721SB Carburetor

The 2 pics below are of a 3461S one dated CE3 left and the other CC3 right. Although the pics are small if you closely the primary throttle linkage on the left carb appears to be correct as it has the hole for the accelerator return spring and matches the repair manual. The primary throttle linkage on the carb on the right does not have the hole for the accelerator return spring. Which is correct? The 3721SB that is currently installed on my 63 has the same linkage as the carb on the right and once again does not have a hole for the accelerator return spring so I just hook it around the linkage itself. I'm confused.
DSC_3714[1].jpgDSC_3985_002[1].jpg

[Kerry A.]

Re: 3721SB Carburetor

I forgot to ask. My car has a May 6, 1963 build date. Will a CC3 or C3 date work for my car? Or should it be CD3 or D3?