Holley Carb Ink Stamp decode
 

Has anyone been able to decipher the ink stamp codes on production line Holley carbs? Specifically, I am interested in 1970 List-4555 for the 1970 Z28. Below is a photo I pulled from a Nova site www.chevynova.org, showing the ink stamp on top of the front fuel bowl, but there are also ink stamps on the top of the rear fuel bowl, secondary vacuum canister and another 2-digit stamp on either the driver's side airhorn or top of front fuel bowl. I would like to correctly reproduce the stamp markings on my 70Z project, but would like to understand the logic/meaning of the codes.

BTW, based on another ink stamp code, I believe the code in the above photo is 4702N4. At tfirst glance I thought the "0" was a "C".

For what it is worth, these photos are from Jason Ayers 1100 mile survivor 70 Z28, automatic.

"For what it is worth, these photos are from Jason Ayers 1100 mile survivor 70 Z28, automatic."

Thanks Rick. Comparing the 4490 carb markings to the 4555 markings, the front airhorn stamp matches the stamped List # and the secondary vacuum canister stamp is the same for both with either "7540" or "754D"....no sure if the last digit is alpha or numeric. I am guessing the stamp on the side of the airhorn could be a date or assembler #. But the six digit stamp on top of the fuel bowls has me baffled.

The 4555 carb referenced has an 021 (1st week of Feb 1970) date stamp on the airhorn. The 4490 carb has an earlier 012 (2nd week of Jan, 1970) date stamp.

This is where us Deuce guys go for LT1 detail pics, just page down - the ink stamps on the 4555 are all there, and its an 021 built Holley....

http://chevynova.org/1970LT1_Engine.html

:)...us Z28 guys also.

Not to hijack this thread (sorry Steve), but can anybody confirm the spark plugs on the reference Deuce engine have been changed? The 1100 mile Z28 has one stripe plugs Acniters and I've seen others that show one stripe as assembly line fitted.

Not mine:
https://www.ebay.com/itm/NOS-AC-R43-...09037?var=null

I also have used information from the motor to restore my 70 z28 motor. My motor after it came from the hot tank had the very same paint marks. Steve Maybe Eric Jackson will see this post and give us a answer.

I wanna see the date on the AC spark plug box. If it's not 1970 dated, it's not real.

Could be a case where there isn't a box? If its an assembly line only item, how would there be a box? Maybe they "walked" out the door back then?
But I agree, I would need some kind of origination evidence or something before spending that kind of money.

Back to the original topic and again sorry for the hijack, but Steve did you come to any conclusions about the ink stamps?

Hi Dave - Nope...not as far as deciphering the codes. My plan is to duplicate the data/fonts on rubber stamps based on the myopic info available....then be prepared to change/correct it if new info becomes available.

Pictures of similar plugs at http://www.1970z28camaro.com/engine/ along with pictures of carb stamps.

Thanks for the update.

Those are on I bet just about every GM Holley from that era. I wonder if the NCRS-Corvette guys know? Maybe not what they are supposed to be on each car, but at least what they mean.

"Pictures of similar plugs at http://www.1970z28camaro.com/engine/ along with pictures of carb stamps."

Yup, very well known site and that car remains a benchmark for Van Nuys built 70 Zs. But, it is a TH400 car, so the carb is different than the 4555 4-speed Holley along with the stamps.

"I wonder if the NCRS-Corvette guys know?"

I still need to check with a friend that has some very good connections in the NCRS...thanks for the reminder :)

Holley Carb Ink Stamp decode
 

I believe the ink stamp codes on the bowls are for either the bowl or bowl/float assembly codes for manufacturing use on assembly. I have seen the same codes for different year carb bowls, so it would rule out a DATE code. The same goes for the vacuum diaphragm, spring, and housing assembly. Just my opinion. Don.

Don - I tend to agree...just wish there was some document trail or evidence verify.

BTW, I spoke to my friend who has restored some nice mid-year Vettes and has been involved with the NCRS for years...basically, no clue, so maybe the ink stamp process was something implemented by Holley after '67??..maybe beginning '70? Not a lot of data points out there, so it's just speculation at this point.

The C3 NCRS guys don't know either... I have been all over the NCRS for the last 2 months researching my 71 LT1.

Thanks for the input James...not sure which direction I'll take on my 70Z project. Might reproduce the stamps and if new info comes to light at a later date, wipe them off with lacquer thinner and start over...

Steve,

Not sure if you are following this thread anymore, but more on this on the Camaros.org site:

http://www.camaros.org/forum/index.php?topic=19212.15

Thanks Dave...no, I had not seen that thread. Unfortunately, there is no discussion on decoding the stamps....just find the correct font, which is, in itself, an excellent step forward :)