Fuel Tank Upgrade
If you've ever had the pleasure of trying to fill one of these G-body ElCaminos (or wagons) up at the gas station, you'll know what I'm talking about. In stock form, they only accept fuel at a very slow rate, and even then will inevitably burp when the gas gets up to the filler neck level inside the tank causing the pump to click off. It seems the reproduction tanks are even worse than the factory ones. Having dealt with this problem before, I wanted to see if it could be solved...
After a little research, I found that someone had in fact been able to fix the problem, but not in the most elegant way. The idea is to get the air from the big sending unit bulge on the top of the tank back to the filler neck. The guy who posted on a forum had used some hardware store barb fittings and rubber hose, which would work, especially if you didn't want to buy a new tank. It's also about the only cold (no torch or welding) way you could do this modification.
For my project, I wanted something that looked a little more factory and wasn't going to have issues with rubber decay. Since I was starting with a new tank, I didn't have to worry about fuel or fuel vapor. I started by drilling a hole on the side of the tank near the filler neck, as high as I could get. I routed the steel tube inside the tank through the internal baffles up into the sending unit dome area. Internally, the tube is wedged between the baffle and the tank skin so the internal part is not loose. On the outside, the tube follows the filler neck and enters the side of the filler neck just below the flap. I cut this end so it just barely sticks inside the filler neck so it doesn't interfere with the flap. I tack welded the tube in place and soldered everything to seal it up.
I would not recommend doing this to a used tank unless you're absolutely sure you know what you're doing. Be very careful with fuel and fuel vapor.
The result is you can put gas in this tank as fast as you want empty to full without a burp or the pump clicking off at 3/4 tank.