| doning | -- 08-21-2011 @ 1:44 PM |
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Okay. I have another issue. I was having problems starting my 37 Ford after it sat over night. I removed the carb top and my float was almost touching the bottom of the bowl. The next day I filled the bowl with gas up to the top, replaced the cover and checked it the next morning and the same thing happened. The float almost touching the bottom of the bowl. The float does not have any holes in it. The gas is going somewhere. I have no external leaks nor do I smell gas in the engine compartment. Are there any lead plugs it could be leaking from? I did not even see any gas in the intake manifold. Any ideas?
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| thirtysixford | -- 08-21-2011 @ 2:06 PM |
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I'm thinking maybe a leaking power valve, but I'm no expert. I would try Stromberg's tech support at tech@stromberg-97.com Mike
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| keith oh | -- 08-21-2011 @ 2:31 PM |
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Your problem is probably fuel leaking past the power valve and ends up in the crankcase. The power valve is located behind the center screw at front outside bottom of float chamber. It is either stuck or worn out or has a weak little spring or maybe if you are lucky just dirty. To properly remove and replace it you need a split blade screwdriver that will straddle the little pin that sticks up (just hoping to be bent) thereby ruining the valve. It is best to remove the carburetor to better see what you are doing. Be sure and replace the washer at least, if not the power valve. After all this it will probably still leak but maybe less at least.
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| supereal | -- 08-23-2011 @ 11:02 AM |
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The Stromberg 97 uses a different power valve than the later carbs. It is located in the bottom of the accelerator pump well and acts as a main jet bypass. If it is faulty, it can allow the bowl to drain. A replacement is contained in a rebuild kit with the part number 67-6590 at C&G. The later, more common power valve, arrived with the "94" carb in 1939, and was used thru '56. Be sure your float is properly adjusted. Fuel level should be 1/2 inch below the top of the base casting when correct. Adding a couple of base to intake gaskets can reduce evaporation caused by "heat soak"
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| 37don | -- 08-23-2011 @ 4:08 PM |
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I don't think the power valve will cause the bowel to drain because it is to low in the circuit. The gas would have to run up hill. The only time a leaking power valve will be a problem is when the engine is running and even then a minor leak would be hard to detect. They are not a very exact system with only a weak spring to hold them closed. I would blame the ethanol gas evaporating as the main cause. I had a similar problem and put the carbs on a piece of paper and monitored them for several hrs and saw no gas leaking but it disappeared slowly somewhere. Maybe evaporation?? Don
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| doning | -- 08-24-2011 @ 2:08 AM |
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I may have an idea now where the gas is going. I removed the carb top and filled the bowl with gas and replaced the top. I did this with the carb off the car. The next morning I checked it and it went down a little. Next, I did the same thing again but this time I plugged the fuel inlet fitting and checked it the next morning. The float was right at the top of the bowl. I'm guessing now a leaking float needle? Probably leaking out and draining back down the fuel line back into the fuel pump?
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| JM | -- 08-24-2011 @ 6:22 AM |
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If it's a rubber tipped needle they do not like this new gas. I would recommend a steel tip needle or a Grose valve. JM
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| supereal | -- 08-24-2011 @ 9:00 AM |
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The fuel pump contains a check valve that prevents "drain back", or siphoning. If you look at the diagram of that carb, you will see that the there is an accelerator pump inlet check valve. When the accelerator pump is worked, fuel closes the check valve, and opens the spring loaded power jet, permitting extra fuel to be forced out through the pump discharge jet and nozzle. Both below the level of fuel in the bowl. Be sure that the pump discharge nozzle is properly seated, or it will leak fuel at its base. The power valve is the logical culprit, perhaps due to a bad spring, or something lodged in the valve. These carbs were far from trouble free, and were replaced by the more reliable 94 carbs in 1939. This message was edited by supereal on 8-24-11 @ 12:22 PM
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