Return line through the carb?

[olddog12]

So after much reading on this topic I have decided that I am going to run a return line back to the tank. There is a 1/4" nipple coming out of the tank just above the sending unit for the return (at least thats what I believe it is). The car has a vented gas cap on it, although not the best way of venting it will suffice for a non daily driver i believe.
So heres my question, can the carb itself be used for the return? Can I run a 1/4" line directly off the carb back to the tank Or do just use one of these type return filters and call it a day.
The carb is a carter 4966 avs, I can post a pic of the carb if needed.

 

[mguner]

You will need a regulated return. Either make a regulator from a brass T or buy one. A calibrated orifice will not compensate for high demand. Most of those style filters were designed as a vapor separator not so much a return.

 

[Johnny Mac]

guys sometimes just tee off of a standard $20 holley regulator. but the correct bypass regulator is this one...(calibrated orifice as mentioned above)

http://paceperformance.com/i-6109320-holley-performance-fuel-pressure-regulator-12-803bp.html

i'm assuming this is to be used with an electric fuel pump?

 

[olddog12]

No this is on a manual pump.

 

[Johnny Mac]

then disregard my post...mechanical pumps vary with engine speed, and should put out a constant 6-8 PSI...some oem style ones have a return, most aftermarket ones don't....not sure what ailments you're looking to correct, but this seems highly unnecessary. if your mech fuel pump is overpowering your carb, you have a hung needle/seat.

 

[olddog12]

I bought the car in a box and have been putting it back together 1 piece at a time. The 318 motor Im using is not original to the car, it has a carter fuel pump on it with no return line also. As of now I have not ran the fuel line until I can wrap my little brain around this return line install.

 

[mguner]

then disregard my post...mechanical pumps vary with engine speed, and should put out a constant 6-8 PSI...some oem style ones have a return, most aftermarket ones don't....not sure what ailments you're looking to correct, but this seems highly unnecessary. if your mech fuel pump is overpowering your carb, you have a hung needle/seat.

Or a compromised float.... Or missing or misaligned float spring (Holley)

The line you speak of was most likely related to the carbon canister and vapor system.

 

[olddog12]

"The line you speak of was most likely related to the carbon canister and vapor system."

You may be correct on that. It will still work for a return lien wouldn't it?

 

[67Dart273]

"The line you speak of was most likely related to the carbon canister and vapor system."

You may be correct on that. It will still work for a return lien wouldn't it?

!!!NO!!!! Not unless you provide some modification for a vent. In fact the 1/4 line you mention IS the vent and must be left open, unless you modify the system

I've posted on this. This gets sticky, because 'there exists' transitional cars in "about 70" depending on whether they were CA cars or not as to whether they had a sealed tank or the old style 69/ earlier vent

Addtionally, there were changes in FUEL CAPS and the carbon can system ALMOST EVERY YEAR starting in 70

START by going to My Mopar and downloading the proper year shop manual for your car .......free.......and it would not hurt to get one year older and one year newer, and read them

Read the section on fuel tanks in chapter 9, "fuel systems" as well as the appropriate pages in chapter 25? or whatever on "emissions"

A bit about the old style venting and fuel caps

http://www.forabodiesonly.com/mopar/showthread.php?p=1970887599

What to do?

There are several ways to skin a cat depending on your skill level

1....Remove the filler tube from the tank if necessary and modify for the 69/ earlier vent, then use your existing 1/4" line for a return

2....Leave the 1/4 line in place, and route it into the air filter bonnet if the carbon can is gone, for the tank vent. Route additional line to the rear for your return.

A......SAFELY braze a fitting into the tank. On mine I flooded the empty tank with CO2 from my MIG bottle and brazed (high temp silver braze) a short tube through the front tank wall

B.......I believe you can buy aftermarket tank senders with a second fitting, for use as a return. Be prepared for gauge accuracy issues, LOL

 

[RustyRatRod]

Del, couldn't he simply run a vented gas cap or is that "not enough"?

 

[67Dart273]

So far as your filter idea, if you have a pump setup that works now, that filter as a return WILL BE FINE. This exact "idea" was used on 440 and426 cars, look it up in the shop manual. The difference was the factory used a 'vapor separator' can instead of a filter, but it worked exactly the same........and orifice.....back to the tank.

My 70 V code (six barrel) RR had this system.

 

[67Dart273]

Del, couldn't he simply run a vented gas cap or is that "not enough"?

True, that would actually function...... I don't like that idea.........way too easy for you to end up with fuel all over the fender. All you need is a full tank and a hot day................

 

[olddog12]

I downloaded the manuals looong ago for the 73 model, mine is a 74, but I wont lie, I get a bit confused reading all of it..
Skill level is much easier than the understanding part for me at times, thats why Im on here.

So I do have a vented cap (agreed not the best of venting methods) but with using this cap, could I use the filter in post #1 and run the 1/4" line back to the vapor line coming out of the tank?

 

[olddog12]

"So I do have a vented cap (agreed not the best of venting methods) but with using this cap, could I use the filter in post #1 and run the 1/4" line back to the vapor line coming out of the tank?"

So can anyone tell me if this will work as a return or am I way out in left field on this?