54 Chrysler gas tank vent

[ah65]

My 54 has a large vent hose in the fuel filler neck and a smaller hose.  The small hose changes to tube and heads toward the front in the frame rail.

Can anyone tell me what it's for?  I suppose it vents something fuel related around the engine.

I can't find anything under the hood and can't locate where it comes back out from the frame.

Thanks, Joe

[tom1954]

Quote

 

On my 54 New Yorker, the fuel supply comes off the passenger side of the tank and is a flare or compression fitting. The line crosses over to the drivers side and  follows the frame rail to the front cross member where it crosses back to the passenger side to the fuel pump. The vent line is a small (abt 1/8") line that follows the rear drivers side frame rail and ends high up on the frame over the rear axle.

[ah65]

Thanks Tom, so the small 1/8" line just ends up at the frame?  Just vents to the air?

I'm trying to solve a hot start vapor lock / percolation problem and was thinking of adding a vented fuel filter and a return back to the tank.  I wondered if the vent ran all the way up front but I could tie on back at the joint at the tank.  Do you have trouble with hot starts?  Joe

[tom1954]

My 54 has the 331 with a 2bl, not sure if this applies to the 4 bl version.

On the 2 bl carb version there is hot water circulating through the carb base to prevent icing in cold weather. I do not know if that is necessary with todays fuel plus the car is not driven in the winter months. That hot water sitting in the base and hoses on shutdown can quickly evaporate some of the fuel in the carb bowl which contributes to the hot start issues.

With that, I have disconnected / rerouted that hot water so it does not flow through the carb base, I then installed pipe plugs in the carb base to replace the nipples sticking out of the carb base.

Also, an electric assist pump, controlled by a toggle switch, could be added in the line to get past a vapor lock issue.

And yes, the vent system on most older vehicles just vents to the air. This holds true into the late 60's / early 70's when air pollution equipment took hold of the automobile industry.

My 68 ElCamino vents to the atmosphere at the filler cap. If I fill the tank to full it actually will spill fuel out the vented cap on right turns or if the fuel expands due to summer heat.

[ah65]

My car is a 4bl and I didn't notice any water passages on the carb.  The manual does mention water in the manifold.  I'm just getting the car back on the road so just finding the hot start problem.  I'm going to try a vented fuel filter first, considered the electric pump for prime but decided to go with the easiest first.  The manual does mention percolation valves built into the carb but says there's no adjustment.  So if I understand the tank vent ends higher then the tank and in a safe place at the frame.  Thanks for the help, Joe