Holly Carburetors - 4 digits

[Robert K.]

Could anyone tell me what this means.......

Holly Carburetor (Front)
3902353 - EU
LIST 3659
0230

Hollly Carburetor (Rear)
3902353 - EU
LIST 3659
1200

I did some research and found that 3659's were the front and rear carbs for the tri-power however, they should only have 3 digits for their date code. I also found some information in the NCRS archieves that talks about "replacement carbs." that were sold (i.e. not put in at the factory) and were 4 digit date codes based on the Julian calendar. If that is true, that would mean that the front is from Jan. (what year?) and the rear is from April (what year?). I don't know if this is correct or what the "0" stands for as the last digit. Also, would these be the correct carbs to use (would they pass judging standards) on a 3894374 ('67) intake? I have a third (center) which has the 3 digit code.....

Thanks for your help!

[William C.]

Re: Holly Carburetors - 4 digits

The are correct replacement carbs, and as such would recieve a minor deduction for the date code. Without some digging, all I can say is they were likely produced after 1971.

[Gerard F.]

Re: Holly Carburetors - 4 digits

More likely 1980,possibly 1990. They didn't switch over to 4 digits until after the 72 model year. Not sure when they switched to hex fuel bowl screws, but if they have slotted fuel bowl screws it is probably the earlier year.

Jerry Fuccillo
#42179

[Joe C.]

Re: Holly Carburetors - 4 digits

First digit for service replacement, Julian dated carburetors produced after 1973 (?)indicates the year of production (i.e "front" 1980 "rear" 1981). Last three digits indicate the day of the year, and can be 001-365(6).

Joe

[John H.]

Re: Holly Carburetors - 4 digits

Joe -

1973-up Holley 4-digit dating is the other way around - the first three digits are the Julian date, and the fourth digit is the year of manufacture.

[Joe C.]

Re: Holly Carburetors - 4 digits

Bob,

See John H correction, which is the correct correction. The correct last digit is the year, not the first, as I incorrectly stated.

[Robert K.]

Re: Holly Carburetors - 4 digits

Joe/John,

Yes, that's what I thought also. However, I still don't understand (is there another way to determine) what "decade" the "0" would stand for? Note that both of the carbs have a "0" as their last digit....... any thought for me here?
Also, for the center carb (3902355, LIST 3660) which is dated 864, would that be looked at as a correct "replacement"?

Sorry to keep bothering you guys with these questions........

Thanks again,

Bob

[John H.]

Re: Holly Carburetors - 4 digits

Bob -

There's no sure way to identify the decade the "0" goes with, although carb details may help (type of bowl screws, etc.). Your center carb dated 8 6 4 would get a 20% deduction (about 3 points) for the date, as would the other two carbs with later 4-digit service dates.