I have made a custom gas tank for my 31 Tudor Sedan out of 1/8" sheet aluminum that fits between the frame rails at the "Z"ed portion of the rear of the frame. I am unsure if it is necessary to vent the tank. I have seen spun tanks used without vents mounted in direct sunlight but I don't know if this method ever caused a problem. Is it necessary to vent my gas tank an if so what methods work the best? If it is necessary to vent the tank should it be into a charcoal canister on direct? Any help is greatly appreciated.
It has to have a vent. If the cap is not vented, you'll need a vent directly in the tank. A rollover valve on the vent line is a good idea. Bob
The tank needs to be vented not only for heat expansion but so the pump can pull fuel from it. A direct vent works fine - either thru the cap or a separate vent. A charcoal canister could be used, but you also need a purge line to the engine to **** out the trapped fumes - probably not worth it.
When I built my tank I did not use a large enough vent. It would **** the tank walls in. After I would kill the motor it would pop back out. I run a 5/8 vent but I also run a very large fuel pump.
weld in a 3/8" female bung in the top of the tank,install a 3/8"hose fitting,use 3 or 4 ft. of hose and attatch it to the filler hose or body frame.be sure to tie a loop in the hose to keep from leaking at the top.you are done...
Thanks for the feedback. It only makes sense that it would need a vent but I have seen several people that didn't vent their tank. They must be surviving with leaky caps.
You can actually get perpose-built venting caps. Perhaps those are what you have seen used before. Second vote for pics!
I think a roll-over vent is critical. Yogi's has a couple,as well as a specific 90 degree elbow: http://www.yogisinc.com/results.cfm/-/Category=1977/search_cd=roll over vent/results.cfm
Pre - cannister cars used vented caps with a one way valve that let air in but did not let fumes out for safety. If you run a plain vent without a check valve, at least extend the line lower than the bottom of the tank so that gas will not spill out if the car is upside down. Better yet is to run the vent line to one side of the tank, down the side, back up to the top, back across the top to the other side, then down the side and below the bottom. That way fuel will not pour out the vent no matter which side the car ends up on in an accident. Try to keep the open end in in an area where it will not **** in dirt as the fuel is pumped out.
a little ot, but... is it okay to have the gas filler in the trunk with a non vented cap and a vent running to the outside, and have my battery mounted in the trunk as well? does the remote vent disperse the fumes well enough? and does the battery need to be in a sealed box? maybe a stupid question but i'm trying to decide which way to go with my battery location.
canister is easy to put in and keeps money ( I mean gas} from evaporating into the air. if you have a vent line get a small plastic inline fuel filter and attach it to the end. keeps out the dirt.
How about the vents in the mooneyes caps... is anything like this available from anywhere off the shelf that can be fitted to other caps??
Here are some pictures of my tank in process and installed. I'm going to add the vent to the fill tube and install a roll over valve.
I'm a little paraniod about this sorta stuff. I've seen some people have fuel filler caps in the trunk, but when you open the cap to fill up, gas vapors are filling the trunk (car interior). Batteries also give off an explosive gas when they are charging. Just think what would happen if you have gas fumes and explosive battery fumes together with a loose battery cable or chaffed cable that may arc. I would go with a sealed battery box, vented to the outside, and an external fuel filler cap. I like safety and function before looks.
Tip from my experience, run the vent up above the tank a good amount, then dow. Nothing like being at a show and hearing your car is pouring gas out everywhere over the P.A.
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