Very late into the 1964 model year, Chevrolet advised dealers of a change in carburetors earlier on the 1964 Corvettes. The date given of 11/26/63 was at the Carter carburetor plant. By the date of 11/26/63, almost 6,000 1964 Corvettes had left the St. Louis plant with the first design AFB carburetors.
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Subject: Recalibration of Carter AFB Carburetors
Model and Year: 1964 800 & 1000 Series with 327" Engines
Source: Chevrolet Central Office Technical Service Bulletin
Bulletin No: DR #674
Section: VIm
Date: May 28, 1964
TO: ALL CHEVROLET DEALERS
To minimize hesitation on acceleration and improve overall engine performance, the Carter AFB Carburetor used on 800 and 1000 Series vehicles with 327" engines was re-calibrated effective at the source approximately November 26, 1963. Carburetors incorporating the latest calibration may be identified by the following numbers which are stamped on the metal identification tag.
3720SA - Units with Automatic Transmissions
3721SA - Units with Manual Transmissions
If hesitation on acceleration is encountered on early production vehicles, the carburetor should be rebuilt using the parts listed on Page 2 of this bulletin.
| VEHICLES WITH POWERGLIDE TRANSMISSIONS | ||
|---|---|---|
| PART NUMBER | QUANTITY | DESCRIPTION |
| 3862088 | 1 | Primary Cluster (choke side) |
| 3862089 | 1 | Primary Cluster (pump side) |
| 7009575 | 2 | Primary Metering Jet |
| 1460475 | 2 | Secondary Metering Jet |
| VEHICLES WITH MANUAL TRANSMISSIONS | ||
| 3862090 | 1 | Primary Cluster (choke side) |
| 3862091 | 1 | Primary Cluster (pump side) |
| 7009575 | 2 | Primary Metering Jet |
| 1460475 | 2 | Secondary Metering Jet |
| 3821716 | 2 | Metering Rod |
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.
© Copyright General Motors Corporation. All Rights Reserved
Article ID: 128
Created: July 6, 2014
Last Updated: July 6, 2014
Online URL: https://www.corvetteactioncenter.com/tech/knowledgebase/article/1964-corvette-service-bulletin-recalibration-of-carter-afb-carburetors-128.html