VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 Adjusting Gas Tank Sending Unit

Any "How to" advice on adjusting gas tanks sending unit for more accurate reading at the gauge would be greatly appreciated. My aftermarket sending unit registers just under three quarters full at the gauge with full tank and with gauge solid on empty I have something like 5 gallons in the tank. Speedo works so it is manageable but irritating. So, thoughts on best process to adjust? I'm thinking bend the float arm? Which direction and how to know how much to bend? Thanks.

. The gas gauge works with a variable resistor. You have to get the correct sending unit. Fortunately Chevy kept the same sending unit resistance on their 12 volt cars but changed the gauge. Unfortunately, the after market sending units used a different resistance. . Sometimes the float sinks. Sometimes the sending unit swing arm rusts solid. Different tanks are different heights requiring different float arms. If it always reads full, be sure your tank is grounded. Here's a web site on fuel gauge: <http://home.znet.com/r1937/Fuel.htm>.
. Good luck, . Lou
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It might be as simple as bending the float arm so the float is lower in relation to the base plate of the sending unit.

Before you make any adjustments test the sending unit and gauge with the unit out of the tank and properly grounded. Will the gauge move through a full range of readings as you move the float arm through its full range of travel?

Also measure the vertical distance that the float travels when you move it through the full range. How does that compare to the inside height of the fuel tank. Yo might need to shorten the float arm so the float travel matches the inside height of the tank

Unfortunately aftermarket sending units are not “one size fits all”.

The most important thing to remember is that this style fuel level gauging system is only an approximation.

Thanks very much for sharing your info, very helpful, best regards, Bob