<VV> Sort of stoopid. - venting gas

[Jim Burkhard]

The Corvair (like everything else from that era) uses a 
vented gas cap. There's a small orifice built in there that 
allows the tank to breathe in air as the fuel is consumed 
and breathe out vapor if the fuel is sloshed around a lot or 
just warms during a diurnal event.  So, just use the proper 
Corvair fuel cap and you are good to go.

As an FYI, to reduce evaporative HC emmisions nowadays cars 
have a system that has a checkvalve to allow breathing of 
air in, but is (normally sealed) to prevent flow in the 
"out" direction.  They do provide a provision to vent the 
tank under high pressure (for a fuel tank) to prevent from 
bursting the tank. Usually said blowoff pressure is around 
50-60 inches of water (about 2 psi). Said tank venting 
should be an unusual occurance though...

Jim Burkhard

Ryan Verthein wrote:
> Hey guys.
> 
> I'm gonna be hooking the gas line up to a tank...and
> I'm not sure how I'll do it, but there should be air
> venting right?  Like, I could just stick a gas line
> into the top, and leave it like that without sealing
> anything up, and be good that way?
> 
> thanks,
> Ryan