54 fuel pressure

[Guy M.]

Anyone know what the pressure should be? Im having trouble with alot of spillage on the rear, the middle one drips and the forward one seems fine. My freshly rebuilt pump might be a bit much. Many thanks

[Chris S.]

Re: 54 fuel pressure

very little - spec is 3 to 4 psi (off memory)
leakage out of the carbs is normal (reason so many caught fire....)

How much fuel?
I get prob 8 drops out of my front one - after I shut it off.....
middle is 2 or 3 and none out of the rear.

Who rebuilt your carbs
There are a bunch of tips and tricks out there -
couple I have heard - but did not try
1. drill a small hole in the fuel pump diaphram - keeps the pressure down
2. tilt the engine - more towards the passenger side

the fuel pumps in these cars really dont suck fuel - they push it up to the carbs.....

I had carbs rebuilt by Daytona in Florida
a little leakage out of the carbs is normal

to protect my steering column - I took a heavy bath mat to a seamtress we know
cut it into strips and added velcro
I wrap the steering column with it.

at a show after operations - I remove the wrap......

[Guy M.]

Re: 54 fuel pressure

Thanks Chris. A fried of mine specialized in Corvairs which the Turbos used these carbs. He did a great job. When I start it , it kicks off normally and after 10 seconds the rear dumps alot of gas then the engine stumbles. I shut it off and gas poures out of the rear, a good 1/4 cup or more and the middle dribbles like yours and the front doesnt dribble at all. Its interesting the rear dumps so much. Pretty slick how you protect the steering colume. I'm at a loss. Icant seem to locte the operating pressure of the carbs in order to test the pump. Thanks again

[Chris S.]

Re: 54 fuel pressure

It is 3 to 4 psi - I double checked.
sounds like the float is mal adjusted or the pump is putting out too much pressure
it should not dump that much....

[Cathy S.]

Re: 54 fuel pressure

When I had a sticky float I also thought that my pump was putting out too much pressure. When I looked it up I found 5-6lbs to be normal. I have 5lbs with small leaks very seldom. The corvair rebuild kits contain better needle and seats than the vette kits. The vette kits are all brass where the corvair have a special plastic tip on the needle that seals alot better. Solved my leaking problem. I agree if its dumping the float is too high. I purposly set my floats a little lower than spec.

[Guy M.]

Re: 54 fuel pressure

Thanks guys, I really appreciate it. Was thinking about putting a Holly reg in which will limit it to 4 psi but I hate the thought of seeing it there. Jurys out

[Troy P.]

Re: 54 fuel pressure

No question that fuel pressure can be a problem and that Viton tips on the needles are a good thing. But I thought it might be useful to point out that the rebuild of a Corvette Carter differs from a Corvair carb in case your friend didn't know. Obvious difference is in the choke so I can assume he caught on to that. Two other differences I recall are that the fuel bowl cover gaskets are not the same (Corvette has one hole in a different place) and the metering rod settings differ as well (Corvette rods should be set deeper thus cutting off more fuel). If the car accelerates and runs great, other than the carbs leaking, he may have caught those two differences. Also there were different pump diaphrams in various rebuild kits.

To relieve pressure from the fuel line after shut down you can drill a tiny hole in the non-return flap valve in the top section of the fuel pump. This will let some of the fuel in the lines past the pump to work its way back into the pump and thus relieve the pressure stored in the lines. That pressure is what is causing the leaking. The leaks stop after enough fuel comes out to relieve the pressure.