QuestionHello, I am having problem keeping this car primed with gas. If I don't start everyday, I have to remove the carb filter and pour gas directly in to get prime back. Which direction do I need to go to correct the problem?
AnswerAbout 95% of old cars are having this same problem. The causes are usually a combination of the characteristics of modern fuels (they evaporate much more quickly than those of the era these cars were designed for), and the history of the carburetor. Modern gas also is very hard on the rubber compounds used in fuel hoses and fuel pump diaphragms, so be sure to check and replace your fuel hoses frequently, or go to the very expensive SAE30R11 hose, which is designed to deal with modern fuel.
If, after driving the car into the garage after a trip, you smell gasoline fumes under the hood after a half hour or so, you have evaporation from the carburetor. You may be able to reduce this by blocking the throttle linkage slightly open, so that the bowl vent on the top of the float chamber is completely closed - make sure it is closing tightly.
Also, depending on the history of the carburetor, it may have been rebuilt mulitiple times by now, and if any of the previous rebuilders made the common mistake of leaving it in the powerful cleaning solution longer than the recommended 10 minutes or so, the sealant coating on the inside of the float bowl will have been damaged or removed. If this has happened, fuel will migrate through the walls of the float bowl and gasoline "sweat" will appear on the outside of the carburetor. There is no cure for this other than to replace the carburetor with one that doesn't have this problem - and the only type you can rely on is an NOS one.
A third problem may be that there is an internal leak in the carburetor, with fuel draining down the inside of the carburetor and into the intake manifold. This can cause serious damage or even an explosion inside the oil pan if the fumes accumulate down there. Pull your dipstick to see if you smell gasoline odor in the oil - if you do, you have this problem.
If this is the case, prepare a flat clean surface in your garage to place the carburetor on, then drive the car to get it good and warm, then remove the carburetor, and without tipping it (which would spill the gas inside), move to the clean surface and place it on a paper towel so you can study the pattern of where the gas is leaking from - wait about an hour and check the paper towel to see if you can locate the leak. It may be that you can spot the area that is leaking, and replacing the failed gasket or seal may cure the problem.
If you cannot locate or fix the leak, but gas is getting into the oil, the way to prevent engine problems or further risk of explosion is to install a fuel shutoff valve at the carburetor inlet, and when you park the car for more than an hour or two, turn off the fuel valve and let the engine idle until it uses up all the fuel in the carburetor, at which time it will stall. At least if you do this, you won't be diluting your oil anymore.
Since modern gas is so much more likely to cause vapor lock, it is becoming more and more common to put an electric fuel pump on old cars, both to get around the fuel drainage and evaporation problem, and to get you going if you experience vapor lock. If you do this, install it toward the back of the car, as low as you can put it and still have it protected from road debris, and wire it to a separate switch that gets it's power from the ignition switch only when "on" so that it will go off with the key. You can then use the pump when you want to start the car after storage, and turn it off otherwise.
I wish there were better answers, but these are all the things I have had to do to get around this problem.
Dick
