how to stop gas from overflowing at fill up

[IRON MAN]

I had a similar problem with my 68 Camaro. Went to ACE Hardware  bought a 10" length of 7/8" diesel fuel hose. I kept it in the trunk and before filling up I'd push the hose on to the gas pump spout and pumped the gas. Some nozzle spout diameters are 13/16" o.d. and some are 15/16" o.d. So you may need to measure. The hose was a tight fit. The hose will follow the contour of the filler neck, which is why I needed it. I had installed a British WWII fighter plane flush mounted billet filler neck and cap. Drilled a 1/16" hole under the locking tab in the cap to vent.

[Racer57]

http://fullcustomliving.com/index.php?main_page=product_info&products_id=537

Have you or anyone you know used it ?

[screamindriver]

I do the rag/towel  routine...I  wrap it around the  nozzle so if it does erupt I keep it from making a huge mess...Then just toss it in the trash at the station..

[1 Wild R/T]

http://fullcustomliving.com/index.php?main_page=product_info&products_id=537

Have you or anyone you know used it ?

It was originally designed to get a vehicle intended for unleaded fuel that had the restrictor punched to pass a California emissions test... Back when you could buy lead fuel the leaded nozzle was slightly bigger so the unleaded nozzle would fit but the leaded nozzle wouldn't.... When guys would hollow out or completely remove the catalytic convertor they would also punch the restrictor so they could use cheaper higher octane leaded fuel....

So yeah, I've installed plenty....  As far as preventing slash back? Well since the nozzle is a pretty close fit it would certainly reduce slash.... Eliminate? Probably not....