VCCA Home Forums TECHNICAL - 1945 AND NEWER 1949-1954 Gas smell

I have a 54 Bel Air that has a smell of gas in the garage. I don’t see any leaks and just had the carb rebuilt. It has a vented gas cap.

I would suggest that you open the hood after it has been run and see if there is any gas on the exterior of the carburetor.

I’ve rebuilt the carb and replaced all the gaskets. I'm curious that it’s the gas cap, it is a vented cap.

The cap has to be vented on these classic cars. They do not have. Sealed evaporative emissions system to capture and burn those fumes.

Some full size Chevrolets in the '60s had a non-vented cap.

Another suggestion for you!! Get under the car and carefully check all along the gas line to see if there is any sign of dampness anywhere on the line. It could be a small pinhole in the line that is allowing just enough gas out to be smelled but not to pool under the car. Check the tank for any damp stain as well as it could have a small leak too.

It doesn't take much gas to evaporate in a confined space to give a noticeable odor. Checking for any dampness or staining likely is your only way to determine where the source. If it is a place not easily inspected it might be very hard to discover.

My point about the carburetor is that many Rochester Bs will leak some from the top of the bowl. The gasket does not do much for stopping this. I have seen a few newly rebuilt Rochester Bs, leak from there. Some were rebuilt in a factory setting. Usually it takes a few iterations to adjust the float level to correct it.

IF THEY LEAK FROM THE "TOP OF THE BOWL" IT INDICATES THE BOWL COVER IS WARPED AND IT RATHER COMMON, YOU THEN SHOULD SEE WETNES IN THE FRONT OF THE BOWL.
MAKE SURE YOUR FUEL PUMP IN NOT LEAKING GAS THROUGH THE VENT HOLE IN THE PUMP.

I agree that it does not take much “seepage” (not leakage) to create a gas smell in an enclosed space.

Just rub your hand around the carburetor and then smell your hand. Also check that the gasket for the fuel tank sending unit is sealing correctly. Once again, just rub your hand(the other hand this time because the first hand will smell for at least a day) around the mounting area.

There are 2 simple steps I take to reduce the gas smell. One is that I never fill the tank really full just before I am going to park the vehicle in the shop. The other is that I let the vehicle sit outside for about a half hour and cool off before I put it in the shop.

Did you have the gas smell before the carburetor was rebuilt?

Yes, I was hoping it would help since it looked like the gaskets were leaking.

I checked the fuel line from the tank to the pump, sending unit, tank fill tube without finding anything.

Do you notice the smell every time you enter the garage, or only after the car has been driven and put into the garage? Do you have a portable gas container in the garage? Sometimes heat will cause the gasoline to expand enough to wick out under the lid and onto the outside surface of the container. Is the smell noticeable just after you have filled the car's tank, or does the amount of gas in the tank matter? I'm just trying to come up with possibilities away from the car as it seems you have checked the car carefully.

I will say that when I have a gas smell due to the carburetor after parking it in the garage, the smell dissipates after a day or so.

On my 41 I have just what you are describing. New tank, lines etc. Only the carb has not been replaced. It seeps a little gas once arm and the garage will smell like gas for the next 24 hours. In my case the carb needs to be rebuilt anyways. I have a replacement that I hope will solve my issue. Only a bit will cause a real noticeable odder.

Rebuilding the carb will help to some extent if there is leakage.

You will never eliminate the gas smell with these vehicles. The fuel system is vented to the atmosphere. There is a vent for the fuel tank and a vent for the float bowl on the carburetor.

Evaporative emission systems were installed starting in the early 70’s.

I have 3 old Chevies and I don't notice a gas smell around them......but maybe I don't have a good sense of smell.

I would think if the oil in the oil bath filter is low fumes could sneak out of from the carb., maybe.