Friend has 77 C3 350 / Auto. The fuel pump is an edlebrock hp unit. If the car is parked nose down, fuel runs into the engine. If the car is parked nose up and doesn't get driven for awhile the fuel bowl in the carb and fuel pump dry out and the car has to be put nose down.

The fuel draining from the tank to the engine has led to a rebuild, after damaging the engine when he tried to start it while the cylinders were swiming in fuel.

First why is the pump allowing fuel to flow unchecked with the car off, and what would be good solution. The new engine is a 400 hp powerplant and needs good fuel flow.

Thanks

 

No need for a fancy fuel pump on a 400hp motor. Get a stock replacement from NAPA.

Also, what carb is he using? Fuel should not just flow downhill into the engine past the filter and needle/seat.

 

Stock pumps are good for far more than just 400HP.

 

Bad float in the carb or dirt in the needle/ seat.

 

Does he have a fuel pressure regulator? Sounds to me like the pump is forcing fluid past a closed needle & seat.

 

Not to be contrary, but in my experience a 400 HP engine will starve for fuel if you hold your foot in it to 6500RPM (with the cam profile in This motor it probabaly quits pulling at about 6000 anyway) I have done this too many times racing. The fuel supply lines on these cars in stock form are not big enough and the stock pump will not keep up on these cars making that much power you will end up with some 17:1 AF ratios. or leaner Ask any Drag Racer. If your running a big block and do a hard launch and don't have and upgraded fuel system you will bust your mouth and nose on the steering wheel when the car noses over...

The edelbrock High Volume low pressure pump is what you need. The line feeding this unit from the tank needs to be a -8 as well as to the carb. Take the fitting out of the carb drill it and tap it with a 3/8 tap and put a -8 AN Fitting there.

"If you don't really run this car that hard forget the above paragraphs"

Your problem sounds like a leaking casting, the body of these carbs are notorious for leaking from the well plugs, or you have a bad needle and seat. I have even seen people over tighten these carbs and crack the center section. Dissassembling the carb and filling the float bowl up and letting it sit will show the leak.

If its the needle and seat I prefer replacing the stock needle and seat with the one piece flat disc type. It will also hold more pressure. I quit building carbs a while ago www.jimboscarbs.com but Going from memory the P/N is 4-556 and can be had from Daytona carb parts. Just for the record a Q-JET when correctly built will out perform a Holley everytime on the Dyno.

FWIW, Jim