TheSaint

How do i decode the date on Holley carbs with 4 digits?

Is this correct for Holley carbs with a 3 digit date code?
First digit is the last number of the year, second digit is the month and the third digit is the week of the month

But when looking at the 4 digit carb with a 1513 date on the picture is the last digit 3=1963 and day 151 in 1963?

Or is it a newer carb?

beekey buzzard

I believe 4 digits are service replacements

TheSaint

I see so all 2818 Holley carbs with a 4 digit date number is replacement carbs but am i right when it comes to the 3 digits dates?

So if you are looking for a correct carb for your old C2 go for one with a 3 digit date if you want a correct dated carb

Mike67nv

Holley started using four digit date codes in 1973 – three digit before that. The link below shows how to interpret the codes but just know that there weren’t any four digit codes before ’73.

http://www.junkyardgenius.com/holley/datecode.html

provette67

Here is an example for an original '66 Holley
651= 1st week of May 1966
First digit is the year
Second digit is the month
Third digit is the week

dharris45

From the picture I assume you have a 65 and I believe the List 2818 is correct for 305 and 365 HP 65's. For a correct carb date, you need to look for 3 digit that start with a 5. So if your car's birthday for instance March 2nd, 1965 then you want a carb dated 531 (5=1965, 3=March, & 1=1st week) or earlier. If you are concerned with NCRS then you look for something up to 6 month earlier than the build date is normally acceptable.

TheSaint

My car is a 1964 coupe with 365 hp engine and factory A/C(C60)
My cars birthday is December 6 1963

The correct carb for my car is a Holley 2818 and i think the numbers should be:
Year-3(for 1963)
Month- October or November
Week- not the most important

karkrafter

Back to my original question , why does my 1966 Carburetor have a 1967 date code?

Nowhere Man

over the counter service replacement

Rob_64-365

My Jan 8 1964 365 also has a service replacement carb, a 2818-1. If I were one of those looking to get every judging point I could, i would start looking for a correct dated 2818 carb. Fortunately, or unfortunately (depending on your perspective on these things) I would much rather put a sniper unit on, than to find a correct, date matched 2818.