Should there be any gas fume/vapor concerns for those who have garages under their living space when using a vented gas cap?
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Re: Vented Gas Cap Concern.
I have four under my house and no problems, even when the doors have been shut for a week or much longer. I do have a snake in there I am trying to get rid of but it has been too evasive for me. It has stopped my wife from throwing junk in the garage, though.
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Re: Vented Gas Cap Concern.
If I catch another snake I am going to introduce it to the mole tracks in my yard like the I did with the last one.Comment
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Re: Vented Gas Cap Concern.
if snakes stop my wife from depositing her crap in my shop. i'm gonna get a boa constrictor in the morning.mikeI have four under my house and no problems, even when the doors have been shut for a week or much longer. I do have a snake in there I am trying to get rid of but it has been too evasive for me. It has stopped my wife from throwing junk in the garage, though.Comment
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Re: Vented Gas Cap Concern.
Gas fumes in attached garages are a large problem with our older Vettes due to their vented fuel systems, specially with today's gas. I had an order from my "Commander" to do something about it and I have it fairly well under control. The measures I adopted are quite involved, including the use of a later model vented cap that has the two way valve - pressure and vacuum. I insulated my carb with a phenolic spacer from an L-75 (good for 35 to 40 * at the carb), use Tomco Inlet valves in place of needle/seats, an electric choke, and finally (and most important), I shut down the engine outside the garage after a drive, let it cool for about 10 to 15 minutes, then move it into the garage. Don't hear many complaints lately. Oh yes! I use more TEL (Max 2000) in my fill up brew.
Stu FoxComment
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Re: Vented Gas Cap Concern.
Hi Ralph:
In my experience with my 67, a properly functioning gas cap is unlikely to cause a problem in the garage. It will only vent out if a lot of pressure builds up inside the tank.
The bigger problem I have with my 67 is the vented fuel bowls combined with today's more volitile gas. When I park the car hot, the gas in the fuel bowls "boils" and releases fumes out the bowl vents. It stinks up the garage for a while. I think this behavior is simply characteristic of the design of the carb and modern gas.Comment
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Re: Vented Gas Cap Concern.
A properly functioning vented gas cap will permit fuel vapor to escape under low to moderate tank pressure. Any sudden and sharp rise in tank pressure will cause the vent hole to seal shut. The cap MUST be oriented as installed in order to properly test!
The problem is that about 99% of these caps are not functioning as designed, and might cause an explosion in the event of a rear end collision. Disassembly of the cap will reveal a rather "fragile" design, easily susceptible to malfunction from dirt, corrosion and foreign objects such as spider webs, etc. Inside, there is a neoprene sealing gasket which is spring loaded and seals against a perforated disc. This seal deteriorates with time by losing some of its flexibility.
JoeLast edited by Joe C.; August 5, 2009, 07:07 AM.Comment
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Re: Vented Gas Cap Concern.
Joe;
Thanks for that information. I had not heard that before. I only recently changed the cap on my 63 in an effort to control venting in my garage (along with other mods). Mine is a new cap and seems to be functioning properly. I have the original and a locking cap that I used most recently. The latter, being chrome, always showed signs of condensed vapors on it from around the small weep/vent hole, and I learned from the discussion on the board that it can be easily removed w/o a key, so I replaced it. It also used to have a suction sound when I removed it so I didn't figure it was working right. The new cap does not do that.
Stu FoxComment
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Re: Vented Gas Cap Concern.
Ralph:
To answer your original question, the concentrations can't get high enough to be a concern either for safety or health. However, it does stink a bit. If you leave your garage door open for a little while after driving it will help a lot.
PaulComment
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Re: Vented Gas Cap Concern.
How about "Agent Orange"?
Stu FoxComment
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Re: Vented Gas Cap Concern.
I don't smell gasoline from the only one (68) of four cars in the garage that has a vented gas cap. However after driving this vented gas cap car and parked in the garage I have smelled gas and know it is from the carb.
I have the Holley carb apart now to install a "Renew Kit". Both old power valves would not hold vacuum. Car had not been driven in awhile and carb had no gas, fuel bowls were dry. I am also going to block the exhaust crossover in the intake and see how it performs.
I keep the vent closed on the gas can stored in the garage I use for the lawnmower to keep fumes contained. I put a piece of tape over my 69 Triumph motorcycle's gas cap vent went parked in the garage. This is probably not necessary, but it is easy to do.
I am thinking about putting rubber caps on the vent tubes of my Holley's when my 68 and 70 are not going to be driven for awhile to reduce the evaporation of fuel from the fuel bowls. I am accustomed to injecting fuel into front fuel bowls after my cars have been sitting for awhile before starting them anyway, so not likely to forget the caps are on the vents.
They always start immediately with the fresh fuel.Comment
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Re: Vented Gas Cap Concern.
Hi Joe:
I once disassembled a 1967 vented cap, and the construction did not correspond to what you describe. All the parts were metal, and they implemented a simple 2-way valve that provides some degree of resistance to air passing in either direction.
I can imagine that a corroded valve assembly could either leak at low pressure or refuse to vent at high pressure, although I have not actually seen these types of failures.
In terms of leaking at low pressure, I doubt that enough vapor would escape through the small outlet orifice to cause any danger. In my experience with my 67, the main culprit for gas fumes in the garage is the vented fuel bowls on the carb.Comment
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