"I don't believe there was a DATE CODE during this period"
There were definitely date codes on Holley carbs of this era. Stamped on the highest part of the bowl cover. If these were hand built outside of the normal Holley 4000 production line, I guess it would be possible to be stamped in a different area, or not stamped at all.
Also, these carbs had a totally unique base casting (throttle body). Not like any other Holley 4000 made.
Sal
AA Carbs were used on the Phase 1 vehicles - both passenger cars and T Birds.
AB carbs were Phase 2 installed on both passenger cars and T Birds
Oldmics
This was on a 1957 D/F Ford (phase one) sold at Maywood Bell Ford in the city of Maywood CA December 1956 (according to previous owner), I bought this over 15 years ago, it's time to sell, look for more Supercharger parts soon, sold as is no returns, it took me over 25 years to find a real supercharger carburetor.
I asked the EBAY seller what the date code is. He said "621". That is the first week of Feb. 1956. Doesn't make sense. Sounds way too early, but maybe they did build them that early. I kind of doubt it though.
My gutt feeling is that the carb has been worked on somewhere along the line and the bowl cover was changed.
Doesn't help answer any questions, but does add to the confusion.
Sal
The very first factory-sponsored supercharged Thunderbirds were actually 1956 models built by Peter DePaolo Engineering in Long Beach, Calif. Several 1957 Thunderbirds were then similarly modified for racing.
1957 Ford Thunderbird D/F-Code Phase I
For the 1957 Daytona Speed Weeks, Ford prepared an armada of special cars including 15 supercharged versions of the Thunderbird. That weekend Harold Mauck ran 138.755 mph for the Two-Way Flying Mile and Ford subsequently put the F-Code supercharged Thunderbird into production.
The D/F-Code was part of a Ford Motor Company Supercharger Program to homologate Ford’s superchargers into NASCAR. As part of 100 supercharged cars, they made 15 Thunderbirds. These had their radio, heater, clock and lighter deleted as well as black tires, no fender skirts and small hubcaps.
All 15 cars were built on January 25, 1957 using a single carburetor engine, McCulloch VR57 Phase 1 supercharger and a heavy duty three-speed manual transmission.
Later that year, Ford offered the F-Code Thunderbird which used the same Paxton-McCulloch VR57 supercharger, supercharger but with the full array of options
NASCAR's Grand National race series had started to gain traction in the South. Carl Kiekhaefer's Chryslers and Chevrolet's new lightweight V-8 threatened to end Ford's stock car racing dominance in the South. So in 1955, Ford's Robert McNamara turned to one of his advisors, Harley Copp, a racing enthusiast, to see how they could remedy the situation. Copp suggested they hire DePaolo to form a stock car program for Ford. DePaolo's success came not so much in running the program as making smart hiring decisions.
As Tom Cotter and Al Pearce wrote in Holman-Moody: the Legendary Race Team, DePaolo technically owned the whole operation, called DePaolo Engineering, to keep Ford from appearing to support racing. "DePaolo did the hiring and firing, and built the specialty parts and pieces needed for racing," Cotter and Pearce wrote.
But DePaolo wanted to base the program in Southern California, to stay close to Bill Stroppe's operations (see HMM#61), and only reluctantly established a shop in Charlotte, North Carolina. Nor did DePaolo directly run the program: He still kept an office in California and hired driver-mechanic Buddy Shuman (and then Red Vogt after Shuman died in a hotel fire) to actually run the Charlotte operation. At the urging of Ford executives, DePaolo also kept a promising driver named Ralph Moody (see HMM#21) on the payroll, but made one key decision in May of 1956 when Stroppe's parts truck driver walked into his office in Los Angeles and asked for a job.
DePaolo recognized John Holman's outstanding knack for organization and decided then and there to hire Holman to replace Vogt. Under Stroppe's management, DePaolo Engineering finally started to win races a month later, and with nine checkered flags from the team, Ford took the NASCAR manufacturer's championship that year.
DePaolo Engineering even had a hand in building one of the famed Battlebird '57 Thunderbirds.