Early A=Gas Spiller!

Now here's a theory for you to ponder. When most of our cars were made, you had regular and maybe unleaded gas. When mandatory unleaded fuel cars came out, the filler neck opening was smaller to prevent a regular gas nozzle from fitting the filler neck. Regular fuel cars have much bigger filler neck openings than unleaded filler necks. Since the pump handles work off of air pressure to trip the handle and prevent overflow, it is possible the newer unleaded pump handles in the older regular filler necks cannot handle the pressures properly and the handle will not trip when it is suppose to. The suction in the handle that is suppose to trip the handle when the tank is full can be bypassed by the larger opening still allowing the handle to suck air even when the tank is full. If there was some sort of insert made or adaptor used that limited the size of the filler neck to mimic newer filler necks, you would not have the overflow and splash problems. After all the newer filler necks basically have a splashguard built into them by only allowing the pump nozzle to fit into the smaller sized opening in the filler neck. Just a thought.