fuel return and vent/vapor lines

[STEVEN DEMASI]

I recently bought a 1971 Cuda with a 426 crate engine. With all great deals come some surprises. This cuda only has a fuel line and no return or vent lines, it has four nipples on the gas tank and two are plugged and two open. My garage completely smells like gas and although I am ok with it, my wife is not. I am looking to to close the loop and am looking for some help, guidance and suggestions. Any and all ideas, pictures, diagrams are more than welcome.

This is what i am working with, gas tank with four vent nipples and only one fuel line. see pics. Also, the trunk has a hole for a fuel vapor base plate kit. see pics

I am thinking i should run three more lines. A fuel return and two lines to a vapor separator. then the separator line to the valve breather cover. Please let me know if this sounds like a good sound idea. I am not totally sure where to run the fuel return too. Was thinking about using something similar to below pics. This will be my first time working with the fuel lines.

thanks for any help
Steve

 

[Rich G.]

This is what should be in the trunk on a 71 and connect to the tank.

 

[Rich G.]

This is an inside pick of mine.

 

[STEVEN DEMASI]

This is what should be in the trunk on a 71 and connect to the tank.

View attachment 65202

any idea where to purchase one. I can not seem to locate one

 

[Rich G.]

I can sell you this one if you want.

 

[Rich G.]

Another picture of the base

 

[Rob C]

How do the lines connect?
My ‘73 is a little different.

 

[Rich G.]

Pretty much the same way.

 

[Steve340]

The vent connections are all shown in the 1971 factory service manual
I believe Mega Parts has all the stuff you need to connect it all up as per factory.
Which by the way works really well.
There is no fuel line return to the tank. If you press ahead with that idea be aware the fuel supply pressure will be low.

 

[Rob C]

Pretty much the same way.

I do t have the extra in turn I tube.

 

[STEVEN DEMASI]

The vent connections are all shown in the 1971 factory service manual
I believe Mega Parts has all the stuff you need to connect it all up as per factory.
Which by the way works really well.
There is no fuel line return to the tank. If you press ahead with that idea be aware the fuel supply pressure will be low.

So do you think I would need a vapor separator?? I thought they require a return fuel line. I could be wrong.

 

[Steve340]

I know the B Body 440 HP and 426 cars have them. Not sure about E Body big block cars.
My car is a factory 340 car and it does not have one, and it is fairly hot here in the summer and it has never vapour locked.
Vapour lock which occurs in the fuel feed line and venting vapour from the fuel tank are two different things although I have seen posts where people get them mixed up.
I am going to say correct you do not need the vapour separator.
But you do need to vent the fuel tank correctly.

 

[Steve340]

I just looked at the pics you posted and there is something wrong with the way the rear shocks are mounted so I would look at that also.
Just checked Mega Parts site and he lists the vapour separator you posted as being for E body cars.
The vapour separator does require a return line to the tank.
Sort out the venting problem first. On my car I have a line that runs from the vent system up to the engine bay and it goes in to the valve cover breather.
When the engine runs the PCV system sucks all the fuel vapours from the fuel tank in to the engine.

 

[Rich G.]

Good catch steve340, the shock plates are on wrong. He need to turn the plates so the shock bolts facing straight back.

 

[STEVEN DEMASI]

Steve340, thanks for catching the shock plates, i am going to correct that.

Also, can anyone confirm the size of the vapor line, i have seen both 5/16" and 1/4". I have a soft copy of the service manual, but really don't see anything about the size and location of the lines. I am confident they follow the fuel line, so i am sure i can figure that out. Just need to get the right size line and clips.

 

[Steve340]

The vent line is 5/16 and it does follow the fuel line.
The fuel tank vapour system does connect a specific way. Make sure you connect all lines to the right connection on the tube up in the trunk.
I have a 1971 Challenger FSM but a good diagram is on page 14-124
Also make sure you have the appropriate fuel cap fitted. The cap on a Challenger allows pressure/vacuum air flow so you do not get too much of either building up.

 

[moparlee]

From the 1971 FSM. The vent line goes to one of the ports on the 3 port valve cover breather cap. In '71 the fuel vapor separater was only used on the 440 & 426.

 

[Challenge360]

Thanks, for posting that diagram. I'm looking for the shield that is pictured. I believe it protects the lines, where they pass through the frame, above the muffler.

 

[moparlee]

Thanks, for posting that diagram. I'm looking for the shield that is pictured. I believe it protects the lines, where they pass through the frame, above the muffler.

Yes the shield does protect the tubes and hoses. It is a hard part to find as they are typically rusted out or removed and I don't think they are re-popped. Luckily the one on my '71 was still in good shape.

 

[Steve340]

Mega Parts has repops of the shield on their site.