What is this AC fuel pump for # 40709

[Ralph S.]

GM # on box 6470110 number stamped on edge of mounting flange is 217C40956 what is this number ? is it a replacement for a 40709 pump I bought it in the mid 80's

[Jeff P.]

Re: What is this AC fuel pump for # 40709

C-3 corvette small block.

[Ralph S.]

Re: What is this AC fuel pump for # 40709

I see the similar thread below the difference in the 40709 vs 40956 is the angle of the fuel inlet. can anyone decipher the stamped number

[Joe L.]

Re: What is this AC fuel pump for # 40709

GM # on box 6470110 number stamped on edge of mounting flange is 217C40956 what is this number ? is it a replacement for a 40709 pump I bought it in the mid 80's

Ralph------


Well, as AC fuel pump histories often are, this is a little complicated.

First the simple part. GM #6470110 is the GM SERVICE part number for the AC 40709 fuel pump. This pump was originally used on 1970-71 Corvette LT-1. It became SERVICE for all 1968-69 Corvette small blocks many years ago when the GM #6417337 AC type 40658 was discontinued by GM (but NOT discontinued by AC). The difference between the 40709 and 40658 is the configuration of the inlet chamber and the angularity of the inlet nipple. The 40658 has a short inlet valve chamber. The 40709 has a long inlet valve chamber.

Now the more complicated part. For 1972 LT-1 the fuel pump part number was changed to AC type 40956 (known in PRODUCTION as GM #6440956). However, as far as I can tell, this pump was never available in SERVICE under either an AC 40956 or any other GM part number specific to that AC type number. Instead, the 40956 was sold under AC type 40709 or GM #6470110, the GM SERVICE part number for the AC 40709. Sometimes a box carrying the AC 40709 or GM #6470110 part number would contain a 40709 pump and sometimes a 40956 pump.

So, what's the difference between the two pumps? I don't think there's any functional difference but I believe there may be a slight difference in the angularity of the inlet nipple.

Does your pump have a short or long inlet valve chamber?

[Ralph S.]

Re: What is this AC fuel pump for # 40709

Thanks Joe, It has the short chamber. What do the stamped numbers mean.

[Joe L.]

Re: What is this AC fuel pump for # 40709

Thanks Joe, It has the short chamber. What do the stamped numbers mean.

Ralph------

That's interesting. I didn't realize the 40956 had the short chamber; I thought it had the long chamber but, apparently, it does not.

As far as the stamped numbers go, the last 5 digits obviously represent the AC type number. The preceding digits/characters I believe are a date code but I have long-since forgotten how to decode these. Dave L. might know, though.

Revised Addendum-----Ralph e-mailed me a photo of his pump. His pump has a LONG inlet chamber configuration, NOT a short chamber. So, the 40956 has a LONG chamber as I have always understood.

[Ralph S.]

Re: What is this AC fuel pump for # 40709

Just sent you a photo it has the long chamber

[Kevin G.]

Re: What is this AC fuel pump for # 40709

Ralph Please check your PM's