I've been around this block before but have never come up with a solution to the problem of fuel spilling out of a stock '32 tank with a stock vented gas cap when the tank is more than half full. Had the same problem with '33-34 tanks as well. I know somebody out there is smarter than I am who can give advice on how to fix that aggravating problem. Any suggestions will be appreciated. Thanks.
You need to run an unvented cap and have a vent put in the tank somewhere, and vent higher than tank. I've seen a vent tube added to sending/pickup unit and worked well. I use a Tanks tank and have NEVER puked gas out.
One of my 32 tanks had a baffle welded into the filler neck by an old time hotrodder. Basically a ring that stopped the fuel as it sloshed up the side of the filler neck. It was only down the filler neck a couple of inches so that gas nozzle reaches below it when filling up.
You problem revolves around the cap gasket or the tank neck being uneven or rust pitted. First look at the cap and make sure that there is a seal on the base of the cap. If there is that eliminates that issue. The next area to examine is the lip of the tank neck, if it is dented, bent or has a rust pit surface it will not make a seal with the cap gasket. If you are unsure of the surface being level slick the tank neck surface with a light coat of grease or vaseline and then place a piece of clear plastic or glass directly on top of the neck and press down, if the surface is not flat the grease pattern will show the high or low spot. If your neck is not flat you then can level it out by using JB weld to build up the surface and sand it flat for a good seal.
The stock tank has a vent in the fuel pick up unit & uses a non vented cap. A non vented cap and a vent in the tank is the solution.
Thanks for all the replies and suggestions! The tank is in a finished car with frame horn covers, etc so I'm not real crazy about taking it back apart to vent the tank but may have to consider that at some point. Dick, I did find some paint and tank sealer on the rim of the neck where the new cap and gasket are supposed to seal. I took a flat block and some emery cloth and cleaned it all up but haven't tried kit yet but will post again when I do Thanks again for all the comments and suggestions!!
#5 plus #6 are the solution, and you say you have a stock tank...if so, the vent is there, part of the sender/fuel pick up unit. See picture on page 13 of the June '32 book... All '32-48 caps fit but most you find are vented...you should be able to fix that with a dab of solder inside the thing.
You probably already know there's a small access hatch for the sender in your floor. Vent is very short and doubtless sloshes out plenty down there in the dark, better not to know...but you could put a piece of rubber hose on it (an added plastic fuel filter will help keep out aerial crud) and run that uphill a bit.
Good suggestion Bruce! I've had the inspection plate off and looked at the factory sender but didn't realize there was a vent incorporated in it. I'll try the tube idea as well. Thank you!
Finally looked at my Tanks tank. Used a flat file to find a low spot. Was low where the cap lock enters the neck on the low side. Bent it back up and rechecked. Will have to drive around to see if works.
After many trials and errors here is what I found to be the problem with fuel spills. Thanks to all who offered advice or suggestions. My tank is an original so had the factory vent as Pete Eastwood suggested. I checked the rim of the neck on my stock tank and it did have some residue of paint and tank sealer so I cleaned it up and checked for flatness using Dick Spadaro's idea of using a piece of plexiglass and some Vaseline. That's a good trick that really tells you a lot. Turns out mine was perfectly flat but still had leaks. In my original post I incorrectly said I had a vented cap but after close inspection I realized that the cap I had was non vented but to be sure I bought a new non vented cap from Speedway that was made in Mexico (starting to get the picture?) and had a cardboard seal. Still had leaks! Bought another cap from Obsolete Ford but turns out that was the same cap from Mexico with the cardboard seal for the rim of the tank. It leaked too, no surprise. So here was the fix for me. ct1932Ford suggested i try a higher quality non vented cap with a neoprene seal. I bought a nice one from Bob Drake that was considerably more expensive than the caps from Mexico but no more leaks. I've since learned that similar caps are available from Retro Ford Parts with a very nice V8 logo stamped in the top. I'm sure you guys know other places as well. Again, thanks to the HAMB'ers who offered help!!