Show me stock 1974 Dodge Dart (sport) gas tank vent routing

[4mulas]

Please.

could someone post a picture or two of the stock fuel tank venting on a 1974 dart (sport if it matters)

thank you

 

[74 360 dart sport]

Please.

could someone post a picture or two of the stock fuel tank venting on a 1974 dart (sport if it matters)

thank you

I do not have a picture at this time but it comes out of the tank just a little above where the gasoline outlet is it runs up and over to the passenger side and runs the frame rail up to the front passenger fender then towards the transmission then runs the front horn to the charcoal canister on the passenger side fender

 

[4mulas]

I do not have a picture at this time but it comes out of the tank just a little above where the gasoline outlet is it runs up and over to the passenger side and runs the frame rail up to the front passenger fender then towards the transmission then runs the front horn to the charcoal canister on the passenger side fender

Ahhhhh……. To a charcoal canister, no wonder why I had no idea. The canister is also long gone on my car. Thanks for the reply, I’ll just make a normal vent with a roll over valve as part if it all near the back..
Thanks!

 

[Bugman]

Holley 1920 R-4003B, 4162 some info there

 

[67Dart273]

Ahhhhh……. To a charcoal canister, no wonder why I had no idea. The canister is also long gone on my car. Thanks for the reply, I’ll just make a normal vent with a roll over valve as part if it all near the back..
Thanks!

"Near the back?" If you mean terminate the vent near the back you will likely run into tank overflow/ siphon problems. The original 1/4" line going up front ended "up high" to avoid that. There is no easy way to do so in the rear. I've suggested to others, to maybe consider welding/ brazing a fitting into your filler tube and duplicate the 69/ earlier simple vent. You'll have to use a "flush" fitting as the tube goes in through the outside of the trunk. The Sport, tho, may be different enough to present other problems

 

[RustyRatRod]

Is there a factory service manual over at mymopar.com? Go look and see. It's a free download and it will have all "that stuff".

 

[Ironracer]

Doubt it's correct, but I came outta the sending unit, up through the trunk ( w/ a grommet) then up to a fitting I drilled and tapped in the filler. Rubber from there to the end of the metal, that I looped higher than said barbed fitting.. Y'all here helped me with that...

 

[4mulas]

Just found a factory service manual. Thanks for all the replies. Will look at it tomorrow. If there isn’t enough elevation to use a simple vent/check valve all below the trunk hump area where the shock mounts are I will likely use a set up similar to my road runner where a 1/4 line comes into the trunk and then goes back through the trunk and exits below the trunk floor to the atmosphere, in a frame rail actually. Similar to the attached photos but the loop will be much higher so ensure it’s height is above the line of the filler neck.

View attachment 1715904061

 

[4mulas]

After taking inspiration from the road runner and looking at it for a while this what I came up with. The 74 tank has one single vent outlet on the tank just above the sending unit. I used the factory hole in the trunk for the fuel sending unit wire as the location for the vent tube which positioned it perfectly inline with the vent on the tank. I just had to enlarge the hole slightly for the proper mopar vent tube grommet as used on a road runner (it’s the grommet for the gas vent or Airgrabber cable). Drilled a separate smaller hole for another grommet for the wire right beside it to the left when looking from the rear. Not visible in these photos.

screw into the package tray are from the bottom. You’ll have to cut it off to ensure it doesn’t poke through your package tray. I put a piece of gorilla tape on top of that.

 

[67Dart273]

MAKE SURE if you do a rear "up and down" and the opening low as pictured above, that you TEST it for SIPHON. Determine the low side if any, fill it close "to the top" of the filler and then park it "vent low" and see if it siphons on a hot day.

The beauty of the 69/ earlier vents is that they were vented way up high in the filler, which formed a "siphon break." The only way they would siphon (a little) is if they were filled up (or heat expanded up) into the neck, above the vent connection. Then they would only siphon ?? a quart, whatever ?? until the level got below the vent line in the filler, and "break" the siphon.

 

[4mulas]

MAKE SURE if you do a rear "up and down" and the opening low as pictured above, that you TEST it for SIPHON. Determine the low side if any, fill it close "to the top" of the filler and then park it "vent low" and see if it siphons on a hot day.

The beauty of the 69/ earlier vents is that they were vented way up high in the filler, which formed a "siphon break." The only way they would siphon (a little) is if they were filled up (or heat expanded up) into the neck, above the vent connection. Then they would only siphon ?? a quart, whatever ?? until the level got below the vent line in the filler, and "break" the siphon.

I do understand what you’re saying but the top of the loop under the package tray is 6-7 inches higher than the very highest point of the filler neck making the “siphon break” you speak of even higher than the 69 style you speak of. The portion that drains into the frame rail only goes into it about an inch and half, which is still higher than the tank itself by about 3”. I don’t ever like to say ‘never’ but I’m pretty darn sure this could ‘never’ siphon.. even if it did the vent tube inside the tank is at the very top of the tank, how much could it ever siphon - a couple once’s until it sucks air? I think the angle the car would have to be parked with the right side low to get it to start a siphon would have to be pretty severe..?

all this said, I never jam as much gas in my cars as I can so I don’t think this should happen to me anyway, but I’ll keep an eye on it and watch. Thanks.

ps. All this said, how in earth did the factory set up with a vapour canister up front mounted pretty low no have siphon issues?

 

[4mulas]

MAKE SURE if you do a rear "up and down" and the opening low as pictured above, that you TEST it for SIPHON. .

edit: The top of the vent loop is 5” above the highest point on the filler neck.

you did get me thinking though and I’ll keep an eye on it. I was also just thinking that if it was a problem down the road I could add a “T” to the top of the vent and run a line to the other side (drivers side) and down to vent into the frame rail. That way if one side started to pull the siphon would also be broken by the opposite side vent line…. Make sense?

 

[67Dart273]

The top of the loop doesn't do squat. The PICKUP must have some way to suck air and form a "break." And the LOW output end if it is below the fuel level will siphon.

If you take a bucket, stick a hose in below the level of the liquid, you could run that hose up 5-6-10 feet, and if you run the opposite end below the level of the fluid in the bucket, "it will siphon"

 

[4mulas]

The top of the loop doesn't do squat. The PICKUP must have some way to suck air and form a "break." And the LOW output end if it is below the fuel level will siphon.

If you take a bucket, stick a hose in below the level of the liquid, you could run that hose up 5-6-10 feet, and if you run the opposite end below the level of the fluid in the bucket, "it will siphon"

yes, but I think you’re missing something here.

The low ‘output end’ as you put it (vent tube exit) is still above the tank height. Assuming the filler neck itself isn’t completely full of gas to the top, which it never will be, and In order for fuel to reach the top of the vent tube then causing fuel to leave low part starting a siphon action the car would have to be near at or near 35-40 degree angle (more like 40, low to the passenger side), so yes the height of the bend in the vent tube does make a difference.

Even if the filler neck was completely full of gas you’d have to be a quite the angle for fuel to reach the top of the vent loop starting a siphon.

it’s not like the exit of the vent tube is starting full of gas and getting yanked out of the tank like a rubber hose siphoning water from a pale and then being put - yes, below the tank level to allow a siphon to happen.

Like I said before, if I ever have a problem with this I will add a T intersection at the top of the loop and do a vent run to the other side as well creating 2 vent sources, each on the opposite side of the car on the same tank vent. That would take care of any siphoning issue. For now I will leave it and try it as is.

Anyway, I’m happy with this and am sure it will work just fine. Thanks for your input regardless..