This mod eliminates the gas can from expanding and contracting with altitude or temperature changes.

Items needed.

2 x press/vacuum relief valve, part #48935K25 from McMaster Carr $7.70 each
1 x Solid gas can lid.
Teflon tape

Tools
Drill motor
1 x 1/4" drill bit (pilot hole)
1 x 7/16" drill bit
1 x 1/4 NPT Tap
Some form of tap wrench

Process
Mark position for two holes for the relief valves, I found the center of the cap, and then marked the holes 1/2" to either side of the center.

Mount the cap in a vise or clamp to a flat surface.
Drill the locations with the pilot hole drill. (Don’t drill through your flat surface)
Drill the pilot holes out to 7/16"
Carefully tap the two holes from inside the cup side of the cap, making sure to keep the tap as square to the cap as possible.
Do not run the tap all the way through; this is a tapered thread, stop tapping the hole with about 1/8" to 3/16" before the end of the tap.
This will allow the relief valve to become tight before bottoming out the threads.

Apply some Teflon tape to the threads on the relief valves.
Screw in the two relief valves into the cap until they are tight.

Dis-assemble the relief valves one at a time, to make a pressure valve put the ball under the spring. Re-assemble the valve and screw down the adjustment screw, blow into the valve while screwing the valve in until you can no longer lift the ball with your breath. Tighten the lock nut.

To make a vacuum valve, put the ball on top of the spring. Re-assemble the valve and screw down the adjustment screw, Suck on the valve while screwing the valve in until you can no longer feel air passing through the valve. Tighten the lock nut.

If you have a controlled pressure and vacuum device you can use that to set the valves.

That’s all there is to it.

 

I had a blitz can last week turn into a football
i now leave the cap a bit looser so it will just blow off through the lid gasket.
these gas cans are not environmentally sound

think when ya rip the evap can off u can rig something up for the gas cans
in a week i noticed through vaporization and venting i have lost about .5 of a litre

so i bought a jiggler siphon so that i don't need to remove the can from the back rack and it simply flows down into my gas tank this solution saves me a lot of issues and the can stays empty till i do a trail run. once off the trail i simply siphon the gas from the can and into the gas tank while I air back up.

 

I have something similar except I push the gas with my CO2 tank, here's a picture of the gas nozel hose setup.



These sell for $120-$150, I have been looking at making them for around $80 + shipping.

 

haha that is great
it would be easy to make
screw on tire valve $7.50
hose to hose bulk head fitting 5.00 or drill hole and solder or weld hose to hose connector
2 feet of hose on one end and 8 feet on the other and another lid 20$
can probably be done for 35.00

i will have to look into that it certainly would move the gas a lot faster than gravity.

 

Don't forget a 5 psi pressure relief valve, I priced all the parts except the lid from McMaster Carr, total cost of parts from McMaster is approx $40.