Help on Holley dates

[mcditalia]

I'm still learning here so bear with me.

What is a "service dated" carb? The link below has a 66 holley application (#3367) that would suit my needs but not sure of the service date code of 3482.

Click here: eBay Motors: 1966 CORVETTE NOS HOLLEY LIST 3367 (item 4590347703 end time Nov-20-05 16:20:26 PST)

Found another auction for "restored" Holley #3367 with date code 5A3, seller indicates this reflects 1965, November, 3rd week.

Yet another auction with D474 date code. This is a used Holley #3367 bought from the current Corvette Central catalog.

How are date codes deciphered for Holley's and is there a difference with service dated carbs?

 

[IH2LOSE]

Here are some notes I have on holley date codes

A carb note .the carb has a 3 digit date codefirst digit =year 5=65 6=66secound digit=month 1=jan 2=feb 3 =march 4=aprill 5=may 6=june 7=july 8=august 9=sept 0=octA=NOV B=DEC

THIRD DIGIT=WEEK 1=FIRST WEEK 2=2ND WEEK 3=3RD WEEK 4=4TH WEEK 5=5TH WEEK

 

[BarryK]

I agree with Larry on the date coding:
1st digit is year, 2nd digit is month, 3rd digit it week.

I believe, but may be wrong, that later dated units had a 4 digit date code but I'm not sure when that started. My Holley 2818-1 is a 4-digit date code so it's a service replacement unit.

to answer your question of "what is a service dated" carb - that's a carb that is the proper type and model for your car but has a later dating than your cars production date. It may be a year or 10 years later. Typically it was because something went faulty with the original carb so it was replaced but with another one of the same model.
At least, that is my understanding of it, but if i'm wrong I'm sure plenty of people will correct me.

 

[IH2LOSE]

As for the differance between a service replacement unit and an original I am not sure what the differances are

From the notes I have the middle unit you listed is the only one I could figure out the dates for and they corospond to what you have listed.

Now If your question has to do with the differences the NCRS would score you I think one of the judges here will help

I am just trying to get a better education with judging myself

This is what I think I have learned so far.

Anydate coded parts on our car must be dated prior to the actual build date of our car.As far as the NCRS is concerned for judging this date can be up to 6 months before the assembly date of our car.

I hope John z jumps in here I need some clarafication on this also

 

[JL66REDCPE]

The 4 digit date on service replacement holley carbs is typically decoded as 1st three digits = julian date; 4th digit = year

 

[BarryK]

Hi John, thanks for that info on the 4-digit dating. Now, on the last digit being the year, the last digit on my 4-digit dated Holley is a "4". I know that doesn't mean 1964 or else it would be a 3-digit code, so is it possible to determine if it is 1974, 1984 or 1994? I assume it's not 2004 as Holley doesn't make the 2818-1 anymore but I don't know when they stopped.

I'm assuming this date code means the 201st day of 19x4 but I don't know that year the "x" would be

 

[JL66REDCPE]

Yep, the last digit is tough to figure out -- it is either from the 70's or 80's. I am not aware of any way to determine the decade. Maybe someone else will chime in. Holley started using the 4 digit date after the 1972 model year.

 

[BarryK]

thanks John. Yep, either '74 or '84 is what i figured but had no way of knowing which. Guess it really doesn't matter in either case, I was just trying to learn more about the dating codes myself so was looking to see if there was an answer to that somewhere.

 

[JohnZ]

There's no way to determine the decade for the 4th digit of a 4-digit date-coded Holley, except that it's always 1972 or later; that's the year they started using the 4-digit date code.

From a judging perspective, a correct carb with a service date would lose 20% of the assigned originality points; carbs usually are allocated 40 originality points, so it would get an 8-point deduction for not having the correct date for the car.

 

[mcditalia]

Interesting stuff,

I would have thought the original Holley date codes would have corresponded to the usual letter format:

A= January
B= February....etc.

The "A" in the middle carb I listed was said to be November. Anyone know what the rest of the months correspond to?

Now all I have to think about is if I want to try to find an "original" Holley and hope I get lucky with a good date code or get a service replacement. Actually how realistic is the 5A3 carb I mentioned with an 11-16-65 stamp on the motor block? 3rd week would start on the 15th (Monday)wouldn't it? One day to get on the motor sounds right

I keep telling myself that I'm not looking to get NCRS top flight or anything but I'm still torn on this issue with many parts. The carb has to be replaced anyway since it is a "universal Holley replacement" and was told is junk.

 

[BarryK]

See Larry's (IH2LOSE) response, he listed all the months by number and letter.
The "A" is November. The carb that is dated 5A3 would be from 3rd week in Nov. '65 as the seller states.

 

[mcditalia]

Woops,

I think the fancy colors that IH2lose used threw me for a loop

 

[IH2LOSE]

Woops,

I think the fancy colors that IH2lose used threw me for a loop

Sorry i was running late for a class this morning,I just cut and pasted from one of my spead sheets I have for date coding on my 66 .

I use the excell spread sheets for everything

 

[JL66REDCPE]

MC -- do you by chance belong to the central new jersey chaper of ncrs ???

 

[mcditalia]

JL,

Nope, just the National, but was thinking of joining this chapter. Got the forms, never filled them out.

 

[JohnZ]

Interesting stuff,

I would have thought the original Holley date codes would have corresponded to the usual letter format:

A= January
B= February....etc.

The "A" in the middle carb I listed was said to be November. Anyone know what the rest of the months correspond to?

Now all I have to think about is if I want to try to find an "original" Holley and hope I get lucky with a good date code or get a service replacement. Actually how realistic is the 5A3 carb I mentioned with an 11-16-65 stamp on the motor block? 3rd week would start on the 15th (Monday)wouldn't it? One day to get on the motor sounds right .

The carb is dated back from the car's final assembly date, not the engine assembly date - the carb was installed at St. Louis, not at the engine plant.

The month code (second digit) for 3-digit Holleys goes 1 thru zero for January thru October, "A" for November, and "B" for December.

 

[paul67]

This Holley is:

3906631
List-3810
1557

So that is the 155th day of 1977?

 

[BarryK]

Paul
I don't know how long they continued production on the 3810 carb so could be '77 or '87.
First 3 digits are Julien date, last digit as year so as you already know it's the 155th day of either '77 or 155th day of '87.

JohnZ mentions there is no way to determine which decade based on the date codes

 

[JohnZ]

This Holley is:

3906631
List-3810
1557

So that is the 155th day of 1977?

Yup, early June, but more likely 1987, based on the hex-head bowl screws.

 

[paul67]

Thanks John. That coincides with the 1988 body-off restoration. And subsequent ownership by an older gentleman who never drove it. I have been able to trace the history of this 1967 back to Florida in 1986 (I have a copy of the title to a used car dealer). It drifted up to NJ in 1997. Again never driven. Then I hit a wall. I did a VIN ad on the NCRS Driveline but no replies.

Then on to PA and again never driven. Strange car. But I enjoy it. The pic shows a frame view from the year I bought it. It looks the same today.

When it was painted last spring it turned out to be no-hit but with some minor stress cracks that were taken care of. So I am thankful for the basic integrity of the vehicle and will sell with a good conscience!

I have a window sheet that shows an original sale at Montgomery Chevrolet, 110 Main Street, Mobile, Alabama. But I do not put much credence in that document as that dealership does not show up on the internet.