Questions on AC 40658 fuel pump

[Paul S.]

Hi all,

I recently picked-up the following NOS 40658 fuel pump for my '69 convertible restoration:

Pump.jpg

Stamping.jpg

Two questions:

1. The AC logo on this pump looks slightly different than the logo on other 40658 fuel pumps I have seen. (Admittedly, I've only seen a few.) Other 40658 pumps I have seen appear to have slightly larger "AC" letters without the raised circle around them. Which is correct for '69? Will mine judge ok?

2. The stamping on this pump is "1G40658". According to the judging guide, this isn't judged, but I am curious about the "1G" part. Is this a date code?

Any help would be GREATLY appreciated!


Thanks,
Paul

[Edward J.]

Re: Questions on AC 40658 fuel pump

Paul, Most of the current replacement and older (80's 90's) AC Delco pumps you'll find are not exactly as the originals, If you still have the original I believe paragon Corvettes rebuilds them.

[Paul S.]

Re: Questions on AC 40658 fuel pump

Thanks, Edward. This is actually a new old stock 40658 Delco pump, and the basic configuration is correct. (As you mentioned, the current Delco replacement pumps are very different from the 40658 pumps -- the bottom portion of the pump is much longer, and they do not have an embossed AC logo at all, among other differences.)

Unfortunately, I don't have the original 40658 pump from my car, so having it rebuilt is not an option for me -- that is why I bought this NOS one. I just want to make sure it looks correct for a '69 from a judging perspective, since these 40658 pumps were used for a number of years, and I am guessing that there may have been variations.

- Paul

[Paul S.]

Re: Questions on AC 40658 fuel pump

Bump...

Anybody ever seen an AC logo like this one on another original 40658 pump?

Pump.jpg

Thanks,
Paul

[Joe L.]

Re: Questions on AC 40658 fuel pump

Paul--------


Here are photos of one of the NOS 40658 fuel pumps I have [none for sale]:


DSCN2297.jpgDSCN2298.jpgDSCN2299.jpgDSCN2300.jpg

[Paul S.]

Re: Questions on AC 40658 fuel pump

Thanks, Joe... that looks like the other 40658 pumps that I have seen. I'm still curious about the one I posted above with the circle around the AC logo, but I think I may try to pick-up a NOS one like you posted just to be on the safe side for judging.

- Paul

[Joe L.]

Re: Questions on AC 40658 fuel pump

Thanks, Joe... that looks like the other 40658 pumps that I have seen. I'm still curious about the one I posted above with the circle around the AC logo, but I think I may try to pick-up a NOS one like you posted just to be on the safe side for judging.

- Paul

Paul-------


My guess as to the reason for the "circle": I believe that, at some point, AC began manufacturing pumps for other brands. Obviously, they didn't want the "AC" brand on those pumps. So, they came up with casting tooling that included a "removable" insert for the logo. The "circle" is the vestige of the insert. Non-AC pumps got "no name" castings, perhaps with a "blank circle".

[Paul S.]

Re: Questions on AC 40658 fuel pump

Paul-------


My guess as to the reason for the "circle": I believe that, at some point, AC began manufacturing pumps for other brands. Obviously, they didn't want the "AC" brand on those pumps. So, they came up with casting tooling that included a "removable" insert for the logo. The "circle" is the vestige of the insert. Non-AC pumps got "no name" castings, perhaps with a "blank circle".

Thanks again, Joe -- that would certainly make sense!

- Paul

[John D.]

Re: Questions on AC 40658 fuel pump

If I remember correctly original pumps have the AC in letters 3/4" high with no circle. In a pinch I put an Airtex pump in my 67 a few years back. It's configuration was almost exactly the same as the AC replacement I took off except no letters at all.

I'm not sure if I would put an older pump on with today's gas...

[Paul S.]

Re: Questions on AC 40658 fuel pump

I'm not sure if I would put an older pump on with today's gas...

Thanks, John... why would you say that? Is there something different about the way the newer replacement pumps are constructed? Or could the internals of a NOS pump actually wear out just sitting on the shelf?

[John D.]

Re: Questions on AC 40658 fuel pump

paul

I'm just thinking that the rubber parts may have deteriorated over time and they were built back in the day when there were no ethanol blended fuels.

[Joe L.]

Re: Questions on AC 40658 fuel pump

paul

I'm just thinking that the rubber parts may have deteriorated over time and they were built back in the day when there were no ethanol blended fuels.

John and Paul-------


I agree. The main thing that would concern me is the possibility that the elastomeric (rubber) components of the long-ago-manufactured pumps are not fully compatible with fuels containing ethanol. Fuel pumps are a highly safety-related item. It's just foolishness to compromise safety for the sake of a nuance like an "AC" logo. While I have many NOS pumps, I'd never actually use one on a driven car. So, that raises the question of why I won't sell them. All I can say is that's a good question that will likely remain forever unanswered.

For me on a driven car, a current manufactured fuel pump is the way to go. As others have pointed out, there is really very little configurational difference between current pumps and originals----mostly just nuances. Although AC-Delco fuel pumps are not currently manufactured by General Motors, they're still the ones I like to use. In fact, the old AC Division of GM hasn't manufactured a mechanical fuel pump in about 30 years.

[Paul S.]

Re: Questions on AC 40658 fuel pump

Thanks, guys -- good points!

Joe -- do you happen to know which current AC fuel pump would be the correct one to replace a 40658? It looks to me like that part number is discontinued.


- Paul

[Joe L.]

Re: Questions on AC 40658 fuel pump

Thanks, guys -- good points!

Joe -- do you happen to know which current AC fuel pump would be the correct one to replace a 40658? It looks to me like that part number is discontinued.


- Paul

Paul------


The AC 40709 replaced the 40658. Unfortunately, it is now discontinued from GM and AC Delco. However, you can still obtain virtually the same pump under other brands. In fact, I believe this is the same pump that was once sold under the AC Delco brand. One brand that still has this pump available is Airtex, a widely available brand, and there are likely others. Curiously, the current 40709, which Airtex and likely others still use as the catalog number for the pump, is configured more like the 40658 than the original 40709. Here are the visual differences between the original 40658 and the original 40709:

1) the 40658 has a short inlet valve chamber; the 40709 has a long inlet valve chamber;

2) the two pumps have a difference in the angularity of the fuel inlet nipple; the outlet fitting position is the same for both pumps.

By the way, the 40709 was the original fuel pump used for 1970-71 LT-1 applications.

[John D.]

Re: Questions on AC 40658 fuel pump

I believe it's AC-Delco #40503.