40956 fuel pump date code?

[Tom S.]

I have an nos AC Delco fuel pump that is stamped "256 R 40956" on the bottom/rear flange. I figure the 256 is the day of the year, the 40956 is the part number, What year does the "R" stand for? I can't seem to figure it out. Any ideas?

[Loren L.]

Re: 40956 fuel pump date code?

If forced to GUESS, I would go for "R" =s "service replacement".

[Terry M.]

Re: 40956 fuel pump date code?

I have an nos AC Delco fuel pump that is stamped "256 R 40956" on the bottom/rear flange. I figure the 256 is the day of the year, the 40956 is the part number, What year does the "R" stand for? I can't seem to figure it out. Any ideas?

The 1970-72 TIM&JG has just exactly what you have, but states the letter code for the year is "not known."

We didn't spend a lot of time or effort on trying to decode the letter = year because this is not a feature that can be easily judged. Again, contrary to popular belief, we had to draw the line somewhere and you have just found it.

If someone wanted to start a survey or cars with known original fuel pumps I suspect the year code could eventually be determined.

[Mike E.]

Re: 40956 fuel pump date code?

Tom, I have H for 1968, J for 70, K for 71, L for 72 pumps in my stash of pics and boxes. Based on that, I would guess 1977 on yours.
Regards,
Mike

[Tom S.]

Re: 40956 fuel pump date code?

Thanks Terry and Mike for for your input. I know the judging manual says that the 70 and early 71 AC Delco fuel pumps used the two letter code and that sometime in 71 (maybe as early as Jan 71) they started using the 3 numbers for the day and a letter code for the year. The example they show in the judging manual for the later shows 3 numbers for the day and a "W" -year not known. Maybe, just maybe when they changed to the 3 numbers and a letter they also continued the sequence of letters after "K - 71", L -72, etc to get to R-77 such as Mike suggested. It's a guess? What puzzles me is that the manual says that the date code and part number should be stamped on the bottom/rear flange, which this particular pump has. I always thought that the later replacement pumps had the stamping in the wrong place (on the top/rear or top/front of the flange). This pump also has a smooth finish to it as the manual says originals do and not a textured finish, as later replacement pumps usually have. I will continue the research and hopefully figure it out. Thanks again

[Tom S.]

Re: 40956 fuel pump date code?

and thank you Loren too, I welcome any input on this question.

[Mike E.]

Re: 40956 fuel pump date code?

Tom, on the side of the body on each side, above the crimped area, are there two small holes or one? And then again up below the cast AC on each neck--two holes or one?
Thanks,
Mike

[Tom S.]

Re: 40956 fuel pump date code?

Mike, I have attached some photos of the stamped area and the weep holes. Let me know what you think, Tom

[Tom R.]

Re: 40956 fuel pump date code?

The revision team for the 3rd edition of the 75-77 TIMJG found the following, currently under review by the NTLs. I'm including a full page from the mechanical section for the fuel pump that includes 70-77 part numbers as well as date codes. Note neither O or Q was not used as a year code.

All fuel pumps use a Julian date code (three digits), followed by the last five digits of the part number. A letter year is used for the calendar year of pump assembly, 1974=N, 1975=P, 1976=R and S=1977. A pump with the code 117S41240 is April 27, 1977 date code. (Fig. M 13.1 and 13.2) A fuel pump installed on a 1977-built in 1976, is expected to show a 1976-year code.

1975-77 _fuel_pump_01Mar21.pdf

[David L.]

Re: 40956 fuel pump date code?

About 10 years ago I started a thread about date codes on AC fuel pumps.
Dave

https://www.forums.ncrs.org/showthre...mp+date+coding

[Mike E.]

Re: 40956 fuel pump date code?

Let me test something out here:
When did AC change from a month/year designation (like LH) to a Julian date/year designation (like 219K)?
Based on the original pumps I have seen, I don't think it was a specific date, like "starting Jan. 1, 71, all pumps will be Julian-dated", but that it was phased in, depending on what model pump it was, and how often they ran production batches of those pumps. I think that it was some time mid-1970 when they started the process.
I would be happy to be proven wrong!

[Mike E.]

Re: 40956 fuel pump date code?

Tom,
I really like the looks of that pump. Production-line pumps in 70-72 used the double hole in those locations. (like the one in your pictures). At some point later on, service replacement pump castings were revised, and they went to a single hole in each of those locations. They also changed the configuration of the lower outlets on many of those pumps along the way on the service replacements. Locations and directions stayed the same, but a square area became tubular, etc.

Mike, I have attached some photos of the stamped area and the weep holes. Let me know what you think, Tom

[James G.]

Re: 40956 fuel pump date code?

Did all the 40956 pumps have the inlet pointing toward the frame?
My original pump on 1971 #21783 is dated 168K40709 - the inlet points toward the motor mount on the pass side.
Other than the inlet direction the external features of the pump are the same as the one pictured above ie weep holes smooth surface etc.

[Terry M.]

Re: 40956 fuel pump date code?

Let me test something out here:
When did AC change from a month/year designation (like LH) to a Julian date/year designation (like 219K)?
Based on the original pumps I have seen, I don't think it was a specific date, like "starting Jan. 1, 71, all pumps will be Julian-dated", but that it was phased in, depending on what model pump it was, and how often they ran production batches of those pumps. I think that it was some time mid-1970 when they started the process.
I would be happy to be proven wrong!

I am not sure if you mean mid-model year 1970 or in the mid'70s, but FWIW my January 29 built 1970 has the LH... code. That is not the actual letters in the code (I don't think). I used to have photos of that code, but my computer ate them.