Fuel Pumps - Was there a difference?

[Donald H.]

In 66, the base 300 HP engine uses the 5594657 (4657) fuel pump and the L79 350 HP used the 6440083 (40083). There are a number of visible differences in the two pumps physically. The most obvious one is the fuel inlet and outlet locations.

Was there a performance difference in the two pumps? Did 40083 have a higher pressure or flow volume?

Thanks,

Don

[Gary B.]

Re: Fuel Pumps - Was there a difference?

Don,

These are what the Airtex reproductions are listed at:

40083
Minimum Free Flow Rate (gph) : 45 GPH @ 1800 RPM
Minimum Pressure Rate (psi) : 6.25
Maximum Pressure Rate (psi) : 7.5

4657
Minimum Free Flow Rate (gph) : 50 GPH @ 1800 RPM
Minimum Pressure Rate (psi) : 5
Maximum Pressure Rate (psi) : 6.5

Gary

[Donald H.]

Re: Fuel Pumps - Was there a difference?

Thanks Gary,

So there was a different performance spec for 66. Sort of funny that in 67 the base 300 hp and L79 350 hp both used the same fuel pump 6440433.

Don

[Joe L.]

Re: Fuel Pumps - Was there a difference?

Thanks Gary,

So there was a different performance spec for 66. Sort of funny that in 67 the base 300 hp and L79 350 hp both used the same fuel pump 6440433.

Don

Don-------



For 1967 Corvette small blocks changed to the Unitac type, "crimped" fuel pumps. This change in design may have offered features that eliminated the need for different pumps. By the way, big blocks always used Unitac type pumps.

[Gerald C.]

Re: Fuel Pumps - Was there a difference?

Joe,

I have a 1967 350 hp and I'm trying to get some information. The build date is 2/9/67. I see that the pump has a "code" on the flange of AG 40433 or is it AC 40433? If that's not the correct code, where would I find a date code?

Thanks,
Jerry

[David L.]

Re: Fuel Pumps - Was there a difference?

Back in 1992 I had a service "40083 IJ" fuel pump ("IJ" = September 1970). Before I sold it I made 2 drawings (top & bottom) because it was different from the 4657 fuel pump which I had several original as well as a few NOS 4657 pumps. The 1963 and 1964 4657 AC fuel pumps did not have a 2-letter date code. As best as I can remember the first 40083 pumps made did not have the 2-letter date code. There is also a hole on the 4657 pumps that have a 2-digit casting year and 1 to 12 radial hash marks ((month of the year). In Feb. of 2011 I started a AC fuel pump date code thread.
Dave

[Terry M.]

Re: Fuel Pumps - Was there a difference?

Just saw this post. I have a 1965 Fuelie. Attached is a photo of the fuel pump that I removed. The pump has the required 3 gussets. That said, the number on the flange is 40083KH. I don't know if this is the car's original pump. I have owned the car since 1990 (never driven, sat under a cover awaiting restoration until now) and I believe the car was not used before that since maybe the early 1980's. It is a 17,000 mile car (per odometer) with factory 4.56 gears. Unlikely that it is really a 117,000 mile car. Anyway, safe to say the fuel pump could be original to the car or, I suppose, could be a service replacement.

Some have reported the letters following the 40083 are a date code. Is there other info to substantiate this. Thanks for any responses.

Terry

[David L.]

Re: Fuel Pumps - Was there a difference?

Terry,
About 11 years ago I started a thread called "AC fuel pump date code research" (see attachment below). This research was based on all the AC fuel pumps that I obtained from Chevrolets in the bone yards, the swap meets, and a survey on this web site as well as a survey the NastyZ28 website. What stated me was when I purchased a complete 327 engine from a a bone yard in Orange, MA, for only $25 which had all the original components with dates that matched up with the dates on the block, including the 4657 AC fuel pump.
IMO, the "40083" pumps installed on 1965 Corvettes originally did not have the 2-letter date code stamped after the AC part # "40083". I am not sure when the 2-letter date code was added to the "40083" pumps. The "40083" pumps were not supposed to be rebuilt, much different design than the "4657" pumps. I believe that your "40083KH" pump is dated November 1968. From 1965 to 1990 is 25 years and things can change. If you have any doubts you should do some additional research.
Dave

https://www.forums.ncrs.org/showthread.php?84774-AC-fuel-pump-date-code-research-data&p=540380#post540380

[David L.]

Re: Fuel Pumps - Was there a difference?

Joe,

I have a 1967 350 hp and I'm trying to get some information. The build date is 2/9/67. I see that the pump has a "code" on the flange of AG 40433 or is it AC 40433? If that's not the correct code, where would I find a date code?

Thanks,
Jerry

Jerry,
I believe the "AG" stamped on your fuel pump is a date code for January 1967. This is one more plus for my AC fuel pump date code theory (see the attachment below).
Dave

https://www.forums.ncrs.org/showthread.php?84774-AC-fuel-pump-date-code-research-data&p=540380#post540380