Auxiliary Tank Filler Neck Upgrade

[nrramse]

My 1970 has the original auxiliary tank, unvented. Its great fun to fill up at the gas station. I have to fill extremely slow, and be fast on my feet otherwise gas belches out and splatters my pants and shoes!

I see that several vendors are carrying a "vented" filler neck, so I'm thinking of trying it out!

Questions:

• Is there some neat trick that will let me connect the vent tube to my original tank? Or do I have replace the tank?
• Some of the vendors advertise that their part uses a "LONG REACH FUEL CAP". My caps are OEM - are they "long reach"? I'd rather keep to the original fuel caps, so if someone could suggest a source for a filler neck that could make that happen, please do!

Thanks, Newell

 

[DirtDonk]

You can’t have both.
The whole “long reach” versus short reach is the difference between vented and non-vented filler necks.
As far as I know, if you’re 70 is not vented now, then the tank doesn’t have the fitting for it either. However, as we have found with Broncos over the years, since it was a running change sometime during the 70 model year, maybe you’ll get lucky and yours was a very late one and maybe the tank has the capped off fitting even though the filler neck does not.
Only way to know is to go there and look.

If you swap in a later, vented, filler neck, you won’t be able to use your caps and will need to use the later model cap. The whole point of the change in caps was so that owners could not retrofit the older fully vented cap to the later non-vented cap.
Because the whole change in fill vent versus no fill vent, came about the same time that the evaporative system (charcoal canister) came on the scene for Broncos.

You can still keep your originals for any restoration project, but you won’t be able to use them as far as I know.
Then again, maybe all this trouble you go to won’t fix your problem.
Lots of us have that same problem, even with the fill vent equipped filler necks.
Good luck!

 

[Oldtimer]

My 68 Bronco aux tank had no vent, and I hated filling it.
About 45 years ago I added a vent to the side of the tank (above frame rail).
Drilled a hole in tank and screwed in a 3/8" brass elbow, and coated with a fiberglass & resin patch to seal it.
There are better products to seal it today.
Drilled a hole in filler neck and soldered in a 3/8 tube.
Bent a piece of 3/8 tube to go between tank and filler vents, and connected with 3/8 fuel line.
Just changed the 3/8 lines while replacing float on sender unit, but have never had any leaks from vent system.

 

[nrramse]

You can’t have both.
The whole “long reach” versus short reach is the difference between vented and non-vented filler necks.
As far as I know, if you’re 70 is not vented now, then the tank doesn’t have the fitting for it either. However, as we have found with Broncos over the years, since it was a running change sometime during the 70 model year, maybe you’ll get lucky and yours was a very late one and maybe the tank has the capped off fitting even though the filler neck does not.
Only way to know is to go there and look.

If you swap in a later, vented, filler neck, you won’t be able to use your caps and will need to use the later model cap. The whole point of the change in caps was so that owners could not retrofit the older fully vented cap to the later non-vented cap.
Because the whole change in fill vent versus no fill vent, came about the same time that the evaporative system (charcoal canister) came on the scene for Broncos.

You can still keep your originals for any restoration project, but you won’t be able to use them as far as I know.
Then again, maybe all this trouble you go to won’t fix your problem.
Lots of us have that same problem, even with the fill vent equipped filler necks.
Good luck!

Thanks Paul - I'm glad to see you're still on here!

 

[nrramse]

My 68 Bronco aux tank had no vent, and I hated filling it.
About 45 years ago I added a vent to the side of the tank (above frame rail).
Drilled a hole in tank and screwed in a 3/8" brass elbow, and coated with a fiberglass & resin patch to seal it.
There are better products to seal it today.
Drilled a hole in filler neck and soldered in a 3/8 tube.
Bent a piece of 3/8 tube to go between tank and filler vents, and connected with 3/8 fuel line.
Just changed the 3/8 lines while replacing float on sender unit, but have never had any leaks from vent system.

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I think I'm going to try to copy this. Its a great idea!

I found a "bulk fitting" on Amazon that seems like it could work on the gas tank.