Would you please help decipher the numbers on the Holley dual-line (not double pumper) carb on my 72 LT-1? It appears to be era correct. I want to know whether or not it could be original and don't have a book on these. Any help would be greatly appreciated.

Stamped on the front of the primary butterfly housing:
3999263 GA
LIST 6239-1
0787

6239-1A 72 Holley 4-brl 350 Camaro Z-28 & LT-1 Manual trans

Does yours have an A after the last number?

PS...

Im not an expert in NCRS unless its the backwards way and I dont know much about Holly's.

There was no A following the 1, but I'll check again just to be sure. TTT.

FWIW, I have what I believe to be an original carb off a '72 LT-1 (at least that's what the guy that sold it to me told me) and it doesn't have an A at the end either.

My 72 LT-1 has
3999263
LIST 6239-1
2542

254th day of 72

Looks like it's........
dated
0=1970
7=month
87= week made

3999263= Chev # the GA are modification codes
Holley # List 6239-1
Hope this helps

I think yours is

2=1972
5= month
42= week

3999263 again the Chev# with no mods
Holley number =List 6239
Looking at the NCRS judging Manual
I think this right, if not maybe someone can correct me? WB

War Bonnet, I thought I read somewhere that sometime in late 72 Holley went from 3 digit date code to 4 digit. 3 digit was as you discribe. 4 digit went to Julian date code. Julian day 1 thru 365 with last digit being the year. I am going by memory though so you now the old saying. Memory is the secound thing to go......can't remember the first.

Bullshark

The Mrs. can tell you what went first

About the codes I don't see any changes listed for later produced 72's, but the manuals have been wrong before. Do you know when you car was built, and does it match up to the week or close to it? WB

Were there that many weeks in 1970?

I believe it's from the begining of the production year? (Sept)
I'm tranfering info from the 70-72 Judging Manual ??? Would be nice to know the cars vin# see if it's a later prod.WB

If you want my VIN, it ends in 13949. Believe the trim tag decodes to assembly beginning in Feb 72, but need to verify.

I read the manual again, your # say's it's a 1970 Holley
Maybe Bullshark can verify his vin against the week. When reading the dates on a Rochester it's the first three digits are the day the fourth is the year. WB

WB, I can't verify VIN right now, the car is offsite in storage. But, It is a late year build because it has A/C

Bullshark

Thanks WB. Do the four-digit numbers on the metering blocks denote dates as well, or something else? Also, do you know of any Holley docs to decode the GA mod codes? I'm good with online searches but would prefer to start narrower.

Interesting that both of these 1972 Holley 6239 carbs on E-Bay also have the GA codes (same seller):
1. http://cgi.ebay.com/ebaymotors/1972-...spagenameZWD1V

2. http://cgi.ebay.com/ebaymotors/1972-...ayphotohosting

He claims the three digit date codes represent (in order) the last digit of the year, the month, and the week of that month. 181 = 1971, 8th month, 1st week.

WB, now I am really confused. I checked my 70 LT-1 and it has a List 4555 with a date code of 9A2 which is 1969 Nov - 2nd week. The cars build date was jan 22 1970. Other List 4555 carbs on ebay have:
044 = 1970 april 4th week in that month
022 = 1970 Feb 2nd week of that month
051 = 1970 May 1st week of that month

Month designators go 1-0 - Jan thru Oct. A=Nov and B=Dec

Three digit date codes only have 1 to 5 weeks in a month nothing bigger.

I thought four digit date codes went like

First three digits = Julian day 1- 365 (366 leap year) and last digit =year 2-72, 3-73 or 83 etc. etc.

Hope someone can shed some light on this subject??????

Bullshark

http://www.chevellestuff.com/generic/holley_carbs.htm

I found this site and it lists a different way they date the carbs and its broken down by "Pre 72" and "Post 71". This site says Corvettes are not included but maybe it will help.

I cant find anything on Corvette specific date codes though other than what I first posted. Sorry

No thats a part number only. Not sure what the modification to the carb relate to the codes, I'll check the manual tonight. WB

You must be correct, but there is nothing in my manual on four digit codes on Holley's??? Can someone else jump in here? TIA WB