Fuel Return Line-Question

[goingballistic]

OK coming down the home stretch on the rebuild.

Hooked up the fuel lines tonight, radiator and fly wheel bolts left, maybe getting it on the road in the next two weeks, can't wait.

While hooking up the fuel lines tonight there is a line that is parallel to the fuel line on the frame. I am assuming that line is a fuel return line back to the tank. Being this motor is anything but stock anyone got any idea what that line should connect to?

I am making the assumption that I don't need it...........any ideas?

Thanks,

Paul

 

[AKRAY4PLAY]

the smaller line is the return line to tank. do not use it for for supply! you will need it. depending on what type of fuel pump you have, dictates were to hook it up. if it is a stock style pump, it will be hooked up directly off the pump. if you have an electric or single in single out pump, like an Edelbrock, you should install a bypass pressure regulator. then you need to hook the return line up to the bypass port. the reason for running a return line is pretty good. street cars have a tendancy to build a lot of heat under the hoods. the heat boils the gas in the lines and/or carb if shut off for a short time. boiling fuel will cause fuel starvation problems because the system is set up to handle liquid not vapor. the return line allows cool fuel from the tank to circulate and stop boil.

 

[goingballistic]

the smaller line is the return line to tank. do not use it for for supply! you will need it. depending on what type of fuel pump you have, dictates were to hook it up. if it is a stock style pump, it will be hooked up directly off the pump. if you have an electric or single in single out pump, like an Edelbrock, you should install a bypass pressure regulator. then you need to hook the return line up to the bypass port. the reason for running a return line is pretty good. street cars have a tendancy to build a lot of heat under the hoods. the heat boils the gas in the lines and/or carb if shut off for a short time. boiling fuel will cause fuel starvation problems because the system is set up to handle liquid not vapor. the return line allows cool fuel from the tank to circulate and stop boil.

By pass pressure regulator? Where and how does that work? Forgive my ignorance here folks. The pump is a single in single out Edelbrock, so fuel goes in, pumps up to the carb. The return line you mention AKRAY4PLAY, I can't visualize how that works.......what is the line bypassing ie what does it connect to? If the main fuel line goes from tank to pump to carb what would the return line bypass, in other words, it's got to hook to something to get a "feed" of excess from somewhere............I'm missing something :confused

 

[Vettehead Mikey]

I'm missing something :confused

You've got the wrong fuel pump and need one that has the correct three fittings on it- in, out, and return (or bypass).

There's no benefit in downgrading to a two port aftermarket pump.

 

[AKRAY4PLAY]

Paul,
the pump you have is fine. you need to plumb in a return line between the pump and carb. there are two different types of regulators to control pressure to the carb. the first is a holley design http://store.summitracing.com/partdetail.asp?autofilter=1&part=HLY%2D12%2D803&N=4294925239+4294839053+4294880914+115&autoview=sku that regulates pressure to a dead head. it stops flow until pressure drops below the desired setting. the second http://store.summitracing.com/partdetail.asp?autofilter=1&part=AEI%2D13301&N=4294925239+4294839053+4294880914+115&autoview=sku is a far better design but more expensive and the one you need. it bleeds pressure above the desired setting back to tank and does not dead head flow. it gives the advantage of constant supply pressure and cool fuel from the tank. the problem with the edelbrock single in single out pump is the fuel gets sheared inside the pump's internal bypass. on hot days in traffic the pump gets hot enough to boil fuel internally and interrupt flow to the carb. it will make your car stumble and sputter like jimmy from southpark. using the bypass regulator will cure all ills and supply the carb with colder fuel than a stock style pump. all you have to do is plumb in a return line from the regulator back to the orginal return line. the return line is the smaller of the two fuel lines running down the frame rail. give me a shout if you have any other questions.

 

[ibanezplayer]

Paul,
the pump you have is fine. you need to plumb in a return line between the pump and carb. there are two different types of regulators to control pressure to the carb. the first is a holley design http://store.summitracing.com/partdetail.asp?autofilter=1&part=HLY%2D12%2D803&N=4294925239+4294839053+4294880914+115&autoview=sku that regulates pressure to a dead head. it stops flow until pressure drops below the desired setting. the second http://store.summitracing.com/partdetail.asp?autofilter=1&part=AEI%2D13301&N=4294925239+4294839053+4294880914+115&autoview=sku is a far better design but more expensive and the one you need. it bleeds pressure above the desired setting back to tank and does not dead head flow. it gives the advantage of constant supply pressure and cool fuel from the tank. the problem with the edelbrock single in single out pump is the fuel gets sheared inside the pump's internal bypass. on hot days in traffic the pump gets hot enough to boil fuel internally and interrupt flow to the carb. it will make your car stumble and sputter like jimmy from southpark. using the bypass regulator will cure all ills and supply the carb with colder fuel than a stock style pump. all you have to do is plumb in a return line from the regulator back to the orginal return line. the return line is the smaller of the two fuel lines running down the frame rail. give me a shout if you have any other questions.

So where does the regulator sit in the line-up of it?
I have an Edelbrock pump as well...do you hook up the regulator on the inlet or outlet?

 

[AKRAY4PLAY]

the flow of things is tank, filter, pump, regulator with bypass back to tank and then carb. i put the regulator as close to the carb as possible to keep the fuel as cold as you can until it hits the carb. thid will keep your carb cold and improve meetering consistentancy.