Service Replacement for 40433 Fuel Pump on late 66 327/300

[Michael A.]

[Joe L.]

Re: Service Replacement for 40433 Fuel Pump on late 66 327/300

I’m in the middle of the engine rebuild on my 327/300 out of my 66 roadster as part of it’s restoration. The fuel pump on it is from ~1990. It’s an AC service replacement pump, not the original 40433. The goal of the rebuild is to be a regular driver, not for show.

I’ve been told that the AC Delco 40503 is the service replacement for this. I’ve seen some posts that say that the AC Delco 40503 is no longer available but then I go on e-Bay and there are a large number of AC Delco #40503 available. Does anyone know if the 40503 that is currently offered is a real AC Delco or something that is sourced from somewhere else and just stamped AC? Any suggestions on a good quality, new service replacement alternative?

Thanks,

Mike------


1966 Corvette small blocks used a "screw-type" fuel pump of AC 40083. For SERVICE it was always GM #6415325 and it's still available today under that part number. Be advised, though, that some modification of the fuel line may be necessary to install this pump.

The type 40503, aka GM #6416712, is the 1967 pump. It is a crimped type pump. It might work for a 1966 but it would also likely require modification of the fuel line(s). It's also still available from GM and AC-Delco dealers.

The AC Division of GM ceased to exist for all practical purposes. Even when it still existed, it ceased to manufacture mechanical fuel pumps a VERY long time ago. All current mechanical fuel pumps are likely manufactured by only one or two manufacturers regardless of the brand they are sold under. Nevertheless, I would only use an AC-Delco branded pump.

For a driven car, I recommend using only a NEW, currently manufactured fuel pump. They will have internal elastomeric (rubber) parts compatible with today's gasolines.

Addendum

For many years GM has cataloged the AC 40083 as the SERVICE fuel pump for all 1966 Corvette small blocks. However, the AC type 40018, aka GM #6415616, is likely more correct for 300 horsepower engines. This is also a screw-type fuel pump and MAY not require fuel line mods. It's also still available from GM and AC-Delco dealers

[Michael A.]