Allen, your ideas sound right on the money to me.

Your tank looks very similar to the '49-'52 Chevy passenger car gas tank I am using in my '65 C10.

The problem with any type of valve in the vent line is it restricts the flow of air/gas vapors in the vent line. I suspect that is part of your slow filling problem.

I used a "sintered bronze vent fitting" (google it) on the end of the hose on the vent on my truck. I did this to prevent dirt and bugs from getting into the gas tank. I attached the vent to the vent hose on the top of the tank away from the exhaust. vent fitting The fitting was purchased at a tractor supply store and it's intended use is as a vent on a hydraulic fluid storage tank (to vent petrochemical vapors).

Your idea of using a filler neck with a vent fitting is a good one, but I doubt you will find one with a 1/2" vent port unless you make one for yourself. My only regret on my installation is that I didn't do this very thing. Mine fills slower than I would like.

More info here: Rear mount gas tank

Hope that helps thumbs_up

John

In the Stovebolt Gallery ~~ "The Orange Crate" 1965 C10 SWB Step Side Build Thread

Inspired to be different. Different in a way of my own, not in a way that others strive.