need fuel return line?

[jveik]

ok i am putting a carburetor on my 383 in my 73 c-10. it will have a block-mounted fuel pump that is driven off the cam old school style. my question is concerning the fact that i need to pick out a sending unit for my tank. heres a couple of questions...

do i need a return line with this carbed setup or just simply a line from the tank to the pump then from the pump to the carb?

what do i do about fuel tank vapors, will i need to have a charcoal canister or can i just have a piece of hose from that port on the sending unit that points upward? how do i get around this problem?

thanks in advance for any advice you guys can give

[maxwedge]

To avoid vapor lock you could put on the type of fuel filter that has a return port for vapor, back the tank.

[777stickman]

I assume (and that's not always a good thing) that you're asking if you need a fuel pressure return line back to the tank.

For a carburetor setup---------no.

For fuel injection going thru a press regulator-------yes

For the vapor thing----------??

[jveik]

ok, so i dont need a fuel return line, but still kindof confused about the vapor control. Do they make gas caps that keep the pressure in the tank equalized with the outside pressure? I know lawn mowers and things of that nature have setups like that and will stop running if the cap gets clogged up, but do car gas caps work in the same manner?

[MrPbody]

By '73, a "closed" system was being used. The vapor is collected in the canister and sent back into the system. The easiest way to set this up would be to use whatever the factory used for that year. Federal emmission laws apply here, too, so if your state required compliance for antique vehicles, you MUST set it up the way Chevy did. Any good repair manual from the era will give you good illustrations and the required parts.

That's the first time I've seen a mechanical fuel pump refered to as "old school".... Man I'm getting old! Unless you're drag racing, a mechanical pump is the method of choice for ALL carbureted engines... (:- (safest, too)

Jim

[jveik]

so if i hook up a charcoal canister, do i just hook the outgoing line from the canister to a vaccum port on the carburetor or is there something else i need to do?

[MrPbody]

I would advise you get a factory service manual and follow the "map" that's in there. There are several components involved here, and I don't remember ALL of them... (:-

Jim