Internally Cast Fuel Pump Date Code

[Bob J.]

Re: Internally Cast Fuel Pump Date Code

Joe,

I agree with Bob Jorjorian. I believe that part of the pump was cast in June 1971 (6 dots with the "71" casting). What is the complete stamping on the edge of the flange which incorporates the number 40083? Are there 2 extra letters or 3 extra numbers along with a letter?

I have owned two 40083 fuel pumps (GM # 6415325 in Gr. 3.900) over the past 30 years. Both had the "AC" casting along with a stamped steel base. One was stamped "40083" on the edge of the flange along with a "PT 5623145" casting on the block mounting face. Another one had a "40083 IJ" stamped on the edge of the flange along with "5623145" cast on the block mounting face. I believe the "IJ" part of the stamping is a date code for Sept. 1970. The AC 40083 pump (GM # 6415325) was sold over the counter for many years as the part number appears in my 1965 Chevrolet parts catalog (Oct. 64), my 1982 Corvette Parts Catalog (Nov. 81) and all the parts catalogs in between.

Is the base stamped steel or cast? I have seen both types on 40083 fuel pumps at the swap meets but most were stamped steel. I think the cast base was probably the original type and the stamped steel base replaced it since it was cheaper to make.

Dave

Dave, I've enjoyed reading your stamped date research on pumps.
On the one pictured, I think the 5324 is just the shortened casting number for the center section,which is sometimes cast with all 7 digits reading 6415324.
I have quite a few center sections around here and all have the familar casting date system with year surrounded by dots or slashes indicating month.
Regards, Bob

[David L.]

Re: Internally Cast Fuel Pump Date Code

Joe,

I believe your "40083 LL" pump was assembled Dec. 1972 ("LL") which somewhat agrees with what I believe is a June 1971 casting (6 "dots" and "71" casting). It's not a fact, just my opinion.

I believe that I still have a few original 4657 AC fuel pumps which I should take apart for research purposes.

Dave

[David L.]

Re: Internally Cast Fuel Pump Date Code

Dave, I've enjoyed reading your stamped date research on pumps.
On the one pictured, I think the 5324 is just the shortened casting number for the center section,which is sometimes cast with all 7 digits reading 6415324.
I have quite a few center sections around here and all have the familar casting date system with year surrounded by dots or slashes indicating month.
Regards, Bob

Bob,

I agree, but at this point in time it's only an opinion, not a fact.
And so the research continues.

Dave

[Joe C.]

Re: Internally Cast Fuel Pump Date Code

Thanks one and all, as I am always amazed by those gifted with forensic skills. I had planned on contributing a Restorer article in the near future on how I rebuilt this pump. I will incorporate some of the interesting theories proposed within this thread.

Joe

[Terry M.]

Re: Internally Cast Fuel Pump Date Code

Thanks one and all, as I am always amazed by those gifted with forensic skills. I had planned on contributing a Restorer article in the near future on how I rebuilt this pump. I will incorporate some of the interesting theories proposed within this thread.

Joe

Joe,
That style of dating (the year and dots in a circle for the month) is common in die casting, as in the case of your part, and plastic injected parts. It is also used in printing -- the boxes our parts come in are often dated in the fashion used here.