L84 Fuel Pump?

[James B.]

I currently have a fuel pump of dubious heritage on my 64. It seems to do the job but I haven't pushed the car to WOT and high RPMs since I put a new 7380 unit on the car. A couple of years ago I bought a "restored" 40083 pump at Carlisle. I put the pump on and it failed immediately. I put the old pump back on and haven't had the 40083 rebuilt as yet (am going to do it now).

I am curious if anyone knows what difference in flow and/or pressure that pump produces over say a basic 300 or 350 horse pump? I am assuming there must be a difference or it would not have been specified on the 365/375 HP cars. The more significant the difference the hard I will work to get it rebuilt quickly.

A related question. I have a vague memory that it was difficult or impossible to get a like NOS diaphragm for the pump. Something was off, color or thickness such that it would receive a deduct in judging??

Will appreciate your help/advice.

[Timothy B.]

Re: L84 Fuel Pump?

James,

The NOS pump overhaul parts are hard to come by and you probably don't want them anyway with today's ethonal gasoline. I think the 1963 L84 cars came with the 4657 pump which is the same as the lower hp engines.

I believe the main difference in the 40083 pump verses the 4657 is the volume the pump is capable of putting out, the pressure is probably the same. I also believe at high rpm, pump pressure should not go below 3psi and idle pressure is approx. 5 1/2 to 6 1/2 psi.