[Tom Vaught]

Going to post some info on how to identify different Holley Carbs today with some pics.

All Holley carbs, except for prototypes that may not have been stamped, will have a 'List Number on them. The List Number could be in various places depending on the carb but the parts will be stamped with a number and sometimes with a Ink Stamp too.

So the List Number will have a Carb Model Number and a Date Code on the carb. Most times on the air horn but in the case of Dominator Carbs it could be on the air cleaner "Ring" or possibly on the side of the mainbody.

Here are some pics as examples:

The 1st pic is a "Chevrolet" production carb and has a Chevy number as well as a Holley List Number and "Vintage" of the carb.
In this case "-1" which means that it is a very early carb in that "List Number" history.

The 2nd Pic is also a Chevy type carb with a "Chevy Part Number and list number but does not have a "Vintage" Number.
Basically the carb is calibrated with the same calibration that was offered in the 60s and 70s.

The 3rd Pic just shows the same info I have posted previously. Pic 3 covers the Square Bore 4150 type carbs and Pic 4 covers the Spread Bore carbs.

Pic 5 shows the list number stamped on a Dominator 4500 Carb (a "List Number" and Date Code".

As mentioned above a "-1" carb would be a 1st Production Run type type carb but if you had a 4150 Double Pumper with a "-6"
on the air horn you would have the first Double Pumper Carb with "4 Corner Idle" Capability. There would have been 4 other changes
to the carb, after the "-1" carb before the "-6" was released.

So this "identifier" helps a lot in swap meets with the "age" of the carb.
Typically the base of the Throttle Body will be stamped with the List Number as well as the Metering Blocks.

The Float Bowls will not be stamped.

Tom V.