carburetor dating help

[Jeff C.]

My '65 has the matching 327/350hp L79, but it has the incorrect steel intake (looking for a 3844461 intake if anyone has one for sale). Anyway, I was also curious if the carb was correct or not. According to my chevy casting numbers book, Holley carbs have a three digit date code. My carb has a four digit code. Here are the numbers, can anyone tell me if I have the correct carb for my car? List = 2818-I Date code = 3165 Thanks!

[Frank C.]

Re: carburetor dating help

Jeff....I don't have the info at hand right now, but I can tell you that your carb is a sevice unit which was not installed at the factory....Regards Frank

[Joe C.]

Re: carburetor dating help

Jeff,

The proper carburetor for your car will have a three digit alphanumeric code, signifying the year, month, and week-of-the-month of manufacture. For example:

5D4

where:
5 = 1965
D = April
4 = 4th week of the month

The carb should be dated within 6 months of the assembly date of your ENGINE.

Joe

[Joe C.]

More

Service carburetors, manufactured after the sixties (someone will chime in with the exact date)have a four digit "Julian Date", where the first digit is the year of manufacture (3, in your case is probably 1973), and 165 is the 165th day of the year.

Joe

[Jack W.]

Re: carburetor dating help

actually, I think the correct carb date will be three numbers, unless you have a Nov (A) or Dec (B) manufactured carb

ex:

531 = 1965 March 1st week

they (holley) went to Julian (4 number) date code in 1972 or thereabouts

[William C.]

Re: carburetor dating help

Also, as the carb was installed at St Louis, the carb date is unrelated to the engine build date, only the 6MO window before the Car Build is needed.

[Jeff C.]

Re: carburetor dating help

I forgot to mention, the carb has a GM part number too, its 3849804 Does this help?

[Gerard F.]

Re: carburetor dating help

Jeff,

You have the correct carb and part number for a 1965 327/350or365HP car but the carb is a replacement carb. With a date code of 3165, the carb is a 1975, 1985, or maybe even a 1995 replacement carb. If it has slotted fuel bowl screws vs hex and other slotted screws, it is probably a 1975 carb. Otherwise it is probably 1985, and up.

They changed the date code from 3 to 4 digits after the 1972 model year. 1973 and up carbs have the 4 digit date code with the year preceded by the day of the year. I guess they didn't expect these carbs to last more then 10 years

Jerry Fuccillo
#42179

[Joe C.]

I Stand Corrected.....

.......on two counts. First, the carb should be dated within 6 months of your car's build date. Second, it is NOT an alphanumeric code, but a numeric code. The second digit only goes alphabetic in Nov (A), and Dec (B).
My apologies.

Joe

[Frank C.]

I,m a little confused

because of the Julian dating. It's been posted here that the original dates ( 3 digit ) on factory installed 2818 carbs vs. 2818-1 service carb dates were ( 4 digit ). Wouldn't that only apply after they reached the 100th day?

[Jack W.]

Re: I,m a little confused

Q: "It's been posted here that the original dates ( 3 digit ) on factory installed 2818 carbs vs. 2818-1 service carb dates were ( 4 digit ). Wouldn't that only apply after they reached the 100th day?"

First of all, don't get too hung up on the 2818 vs. 2818-1 as being relevant to the oem vs. service carb issue, 2818-1s were installed on 65 L76 and L79, AFAIK.

as for the date distinction, three numeric vs four numeric date codes is an easy way, since Holley dated their carbs using the three number system (year - month - week of month) until 1972 or so.

revisiting the year - month - week of month format, it makes no difference once the 100th day of the year is passed. If the carb was built on April 2 1965 (after 100 days into the year as near as I can count) then it would get a date code of "541" => year = 5, month = 4, week of month = 1

[Gerard F.]

Re: I,m a little confused

Frank,

The 2818-1 was a factory carb if it had a three digit date code of Year-Month-Week within the production year of the application, which preceded the vehicle assembly. For a 2818-1, the first digit would be 4 or 5 for 1964 or 1965.

A service replacement 2818-1 could have a three digit date code up to 1972 if the date code was after the vehicle assembly date. A 5A3 date code (1965 November, third week) would be a replacement as the date would be in the 66 production year. A first digit of 3 would be 1963, and a first digit of 2 would be 1972.

Supposedly, in 73 or thereabouts, they started the 4 digit code which was Day of the Year with the Year after. 0025 could be Jan 02, 1975. The first three digits could theorectically be up to 365 (or 366 in a leap year).

Since the 4 digit date code had only 1 digit for the year, the date code would repeat every 10 years. 0025 could be Jan 02, 1975, 1985, or 1995 if they still produced that model (list no) of the particular carb.

Slotted fuel bowl screws and other slotted body screws are indicative of pre-1980 carbs, although I'm not sure when exactly they switched to the hex fuel bowl screws.

Does this stir up the mud?

Jerry Fuccillo
#42179