My first carb swap, not sure how to run the fuel from the stock tank/pump? The lines are still there from the original 305. Can I run the stock pump, and block off the one on the carb motor? Or can I unplug the stock one and just use it for a sending unit, and run the lines to the pump on the motor? Just looking for the easiest route. Thanks!

 

If the mechanical pump on the carbed engine has a return line, connect the supply and return lines from the stock pump to the mechanical pump. Leave the oil pressure switch in to power the stock pump while the engine is running, and use a wire from the starter solenoid to the fuel pump relay to power the pump while you're cranking.

 

What if the pump on the motor doesn't have a return line?

 

Then you need a mechanical pump block-off plate, and remove the mechanical pump, and use a Mallory 4309 return style fuel pressure regulator to reduce the fuel pressure down for a carb, and use the in-tank pump.

Or else, drop the tank, remove the intank pump, insert a carb pickup line in it's place, and use the mechanical pump without the in-tank pump.

Only two options.

 

By drop the tank you must mean cut a trap door under the carpet. Lol. Thanks! There's no way to somehow suck fuel through the stock pump while it's disconnected? And how do I retain the fuel gauge?

 

He means jack the car up and remove the Fuel tank from the vehicle. cutting "Trap Doors" under carpet is a really bad idea.

 

Sucking fuel through the dead in-tank pump is posible, but it's a very short-lived scenerio. The in-tank pump creates too much restriction for a mechanical pump to draw through, and external electrical pumps simply burn up after a few weeks/months trying to draw enough fuel through the dead pump.

The gas guage has nothing to do with the pump (except for the fact that the sender and pump are part of the same assembly), and thus your gas guage will work as it always has.

 

Haha I knew what he meant I was just joking, cause I don't look forward to dropping the rear. Why is the trap door a bad idea?

 

Because almost nobody does it properly and just makes a big mess.

 

what about using the return line from the fuel injection set up, as the pick up for the mechanical pump? would that work?

 

IIRC, the return line just sorta dumps the fuel back in the tank near the top, it doesnt go all the way into the tank like the supply line.