Updated: Nov 3
For the most part if it is a factory carb it’ll have a manufacturer part number. That will be on the top line. Ford carbs are included in these photos.
Ford part numbers are fairly simple to understand.
9510 is an internal part number for carburetor.
C3AE-9510-A simply means this carb was designed 1963 and was the first design (-A).
Please understand as there is confusion here. This is an engineering code. The part was designed in 1963. The Holley code tells when it was actually cast. It is common that a 1963 design has a casting date of 1968.
Next line will say “list”
This is the numerical listing, aka Holley part number. This is what your carburetor is.
List 3793, 4118, 2143-1, 4412 pictured.
Ok last/bottom line is date code. Early versions had a three digit code.
It goes YEAR, MONTH, WEEK.
So first number is the last digit of the year. Sevond number is month. 1-9 is Jan to September. 0 is October, A is Nov, B is December.
So 722= second week of February 1967.
605= fifth week, October 1966
073= third week, July of 1970.
4B2= second week, December of 1964
Ok, four digit codes come later.
First three numbers = day of the year. Last digit is the year.
So 2391= 239th day of whatever freakin year ends i
If you have no list number, measure the venturi, measure the throttle bore. Throttle plates are stamped with numbers like 107, 109, 118, 172, etc. This will at least tell you what size.