Carb Question Regarding Carter Carb
Can anyone decode a Carter Carb for me. I do not have the judging manual for a 65. A friend of my just bought a 65 to restore and the carb that can with the car is a Carter and the number on the front is 3720SB and then on the bottom is A7. His car is a 65 327/300hp powerglide. Any help is appreciated.
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Re: Carb Question Regarding Carter Carb
I did some previous research on 3720s carters and (date) A7 = JAN. 67, also, I picked up the idea that 3720SB is used for both a/t + manual trans. 3720SA is used for auto trans. only. I have a 3720SA dated B4 = FEB. 64, if your build date supports a 64 carb. if needed. Steve -
Re: Carb Question Regarding Carter Carb
Steve
What is confusing to me is this the number A7 listed under the carb number. I thought only Holleys carbs were used in 67 not carters.Comment
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Re: Carb Question Regarding Carter Carb
I checked 67 chiltons and in fact, carter stopped 1965. So, now I am getting really confused about the date. Chiltons list 3720SA for 1965 only, 3720S for 1962-1964 only, 3720SB is not listed, a guess is that 3720SB was a service replacement, but keep in mind this book was for 67 and older vehicles. SteveComment
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Re: Carb Question Regarding Carter Carb
I am thinking you are correct about this unit somthing just is not correct with the numbers that are on this unit. I did not think myself that this unit was not original to this car from the info I have. Thank you for the info it has been very helpfuComment
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Re: Carb Question Regarding Carter Carb
The 64 Corvette Shop Manual lists;
-3721S (3851761) for manual transmission cars.
-3720S (3851762) for automatic transmission cars.
The 65 Corvette Shop Manual lists;
- 3721SA (3851761) for manuals &
- 3720SA (3851762 for automatics (Note: same p/nos, as the 64's).
The 1963 models 3460S and 3461S are also identical to the 3720S and 3721S, only they were exclusive to the 63 (L-75 [300hp] & L-76 [340hp]). As the 3461S was used on the L-76, it had richer jetting and that jetting carried over to the 3720S and 3721S in 1964. However, since the 64 and 65 applications were only on the L-75 engine, the updated SA and SB versions of the 3720 and 3721 models had various jetting revisions (leaner)dealing with the primary main jets and metering rods, (as well the Idle jets [richer] in the primary venturi clusters), and the secondary main jets (leaner).
The 3460S and 3461S carbs differed in their throttle linkages in that only the 3460S used with automatics had the lower hole for connection to the transmission linkage. Most 3720S and 3721S I have seen all have that connection hole. Besides the throttle linkage variations for the transmission connection, some models have a hole for the throttle return spring in the throttle arm, while others do not and you must connect the spring to the accelerator rod in place of the cotter pin.
I have both a 3720SA (K4 [11/64]) and a 3721SB (E9 [05/69]). The 3720SA was substituted by the Corvette Service Garage that stole my original 3461S, and I purchased the 3721SB in 1980 as a service replacement carb. The latter suggests to me that the service carbs were made at least into mid 1969.
I know of all the above variations, but I would need a lot more study and sampling to determine where to draw the lines as to which carb had which features. Just when you think you have it figured out, then a new wrinkle rears it's ugly head. Much of what is written in aftermarket service manuals is wrong and no one will ever take the time to correct them, so don't accept them as gospel.
Stu FoxComment
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Re: Carb Question Regarding Carter Carb
Stu
Thank for the info, I hear you.Comment
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