Identifying big block fuel pumps

[Ed M.]

I have just removed the fuel pump from my car. It is a long base AC pump with a cast top and gold dichromate bottom. The numbers stamped on the lower part of the mounting flange are 289K40482. I assume this is a julian date. What does the K represent? I also assume this is the correct pump for a 427. How else can I be sure this is an original pump? Thanks for the help.

[Joe L.]

Re: Identifying big block fuel pumps

Ed-----


AC Type 40482 is the correct fuel pump originally used for most 67-69 Corvette 427 installations. The last I checked, it was still available from GM under the original SERVICE part number, GM #6416741(assembly line fuel pump part numbers were NEVER available in service, but the pumps are, generally, identical to service pumps). I've never been able to learn what the other stamped coding on the pumps denote, but I'm still looking to find out.


Modern-day GM replacements for fuel pumps are usually configured slightly differently than the originals. Often times, the "AC" logo is absent or otherwise positioned on the pump's upper casting. Most current production pumps no longer use the "stamped in" coding, but now utilize laser printing. As far as I know, AC-Delco no longer produces mechanical fuel pumps in-house, as they did for many years. Nowadays, I believe that the pumps in Delco boxes are manufactured by other vendors to GM.


I DO NOT RECOMMEND using old fuel pumps in driven cars and I DO NOT RECOMMEND using any "rebuilt" original "crimp-type" fuel pumps. In a Corvette, if the fuel pump diaphragm fails, most of the fuel in the tank will siphon out onto the ground. If the car happens to be sitting in your garage when this happens, you can have quite a problem on your hands. This very thing happened to me about 20 years ago. Now, I change fuel pumps just like oil filters, except on a more extended schedule(about every 3-4 years).

[Joe L.]

Addendum To Above Post

By the way, I forgot to mention that ALL Corvette big block engines originally used only the "crimped" type fuel pumps. The "screw-type" pumps were only used on small block engines and this usage ended after the 1966 model year.