WNDOPDLR

I think the fuel pump on my 60 is giving up the goast. Fuel drains back out of the carbs while the car sits overnight, and my suspicion is that a check valve in the fuel pump has failed. The fuel pump on the car at present is a screwed together type and I have no idea if this is correct or not. If I need to replace the pump, I might as well use the correct pump, and, if this is the correct pump, I can just rebuild it.

My two questions:

Is this the correct pump for a 60?

If so, where can I get a rebuild kit?

Thanks for looking .

Bill Pilon

Carbs draining down don't have anything to do with the fuel pump, once the fuel is in the carb bowl the fuel would have to run uphill to get back to the fuel pump. By the way most old carbs do leak down over a period of time.--Bill

Frankie the Fink

I don't know if the fuel pump could have a siphon effect on the carb or not - however no carb should leak down overnight.

The '60 should have a screw together fuel pump and you can get a rebuild kit or get a nice AirTek replacement pump from almost anywhere. Beware tho some of the rebuild (and aftermarket pumps) have excessive pressure due to thicker diaphragm rubber and tougher springs.

But again, the pump may not be the problem. If you remove the air cleaner in the morning and work the throttle sharply by hand do you see a healthy squirt of fuel from the primary bore nozzles ?

John McGraw

It is almost impossible to answer if it is the correct pump from the information given. The pump for your car is a AC 4656 pump, and that number should be stamped in the mounting flange.This is one of the most valuable AC pumps out there, but unfortunately, this is one of the most counterfeited pumps out there. There are lots of people re-stamping 4657 pumps as 4656, but there are subtle differences, that are the true mark of a real deal 4656 pump. If you post some pics of the pump, there are lots of guys that can tell you if you have the real deal. If it is a real 4656, it is worth at least $200, even as a non-working core. It would most assuredly be worth rebuilding. There are lots of functional replacements for the car, that can be bought pretty cheap, but don't get rid of the old pump, until you know what you have.

As others have said, carbs will not drain down because of a bad pump. the fuel level is lower than the needle and seat, so it is impossible for the pump to siphon the float bowls dry.




Regards, John McGraw

WNDOPDLR

Thanks guys for the responses. In answer to the question about accelerator pumps working after the car sits NO. That is what made me think the gas was draining back. After I turn it over and the fuel pump re-fills the carbs, everything is fine. There are no obvious fuel leaks in the car, but the float bowls seem to be dry. I think I will remove the carb tops this morning before I crank it and see how much gas is in the float bowls.

John- thanks for the feedback about the 4656 pump. I bought a cheap replacement at O'Reillys and will switch it out until I can get the fuel pump rebuilt. When I get the old pump removed, I will post some pics if I can figure out how to do that or at least respond to everyone with the number stamped on the old pump.

This is not an NCRS car. The current engine is a 327 with an Edelbrock manifold and two Edelbrock carbs. The fuel line between the carbs and the fuel pump is an assemblage of parts never seen by GM. It has worked well for 10 years, but the past year has developed this fuel/starting problem, and, after much grumbling and procrastination, I figure it is time to fix it.

Thanks again for all the help guys and I will get back to you.

John McGraw

There are several makes of carbs out there, that have a design defect that allows the float bowls to drain down when not in use, the gas actually drains in the intake manifold. Spread bore carbs like the Quadrajet, are the worst offenders of this problem, and there have been several attempts to cure this problem, some are effective, and some are only effective for a period of time. The metering rod wells are bored completely through the carb, and then the wells are plugged with lead plugs at the bottom of the wells. These plugs will start to leak after a few years, and you have to install one of the fix kits.

Check the web for known problems with your model of Edelbrock carbs, and you will probably find a similar problem.

Also, with modern gas, it is very common for the fuel bowls to simply boil the gas out of the bowls, due to engine heat. If you start the engine and then shut it off before the engine gets hot, and the bowls stay full, then you have a percolation problem. About the only thing that can help, it to block the heat riser passages, and to put an insulator under the carb base.


Regards, John McGraw

John McGraw

I just went to Edelbrock's website and looked at what they sell. It appears that the majority of the carbs that they sell are Spreadbore carbs, and they look like clones of the Q-jet carb. I would bet that the same defect that affects Q-jet carbs, is also applicable to Ebelbrock carbs as well. I would bet that the metering rod wells are leaking into the manifold, when left sitting.



Regards, John McGraw

WNDOPDLR

Thanks again John.

3310vette

Attached are two photos of a real 4656. The 3rd photo is what a typical restamp looks like where the seller grinds down the casting line and stamps over the smooth area.