Thanks for the advice Liketoroam but I'll stick with what my Dad told me.
Fuel tank installation continued:
I now have some practice with threading holes into thin aluminum but before starting on the tank I'll have to figure out how to place the cover plate for the fuel sending unit. Here is the sending unit. Notice the round plastic float attached to the brass rod.
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That float extends off to the side of the sending unit. Looking at this diagram of the fuel tank.
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The platform for the sending unit is at the right end of the tank so I have to be sure to install the sending unit so the float extends to the left.
This sending unit is made to be used in tanks with a diameter of from 6 to 23 inches. It has to be adjusted to match my 8" diameter tank. First step was to disassemble the different pieces.
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In the picture you can see the cover plate with the main rail. Laying above it is the extension rail and above that is the black rectangular sending body.
Here is the measurement diagram in the instructions. This shows how to position the sending body and the length of the float arm
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Need to find the dimension "A". Measure the depth of the tank from the sending unit platform. 8 - 1/2" deep.
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This is supposed to be an 8" deep tank so the platform should be 1/2" high. Double check.
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Here is the table that corresponds to the diagram. The "A" measurement is 8.00 so that gives 4.00" for "B" and 4.90" for "C".
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The "B" setting is how far down to place the sending body. Have to add 1/2" to the "B" dimension to account for the raised platform. The extension rail won't be needed so mount the sending body to the main rail. On the sending body, measure to the anchor point for the float arm.
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Next the "C" setting. This is how long to make the float arm. The table shows 4.9" which using "The Pocket Ref" translates to near 4-7/8". The instructions have you add one inch to that length for the anchor point. Measure and then mark the correct length with tape.
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Cut the float arm and then mount to the sending body. The float must be to the right of the sending body.
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See if it fits.
It does, just.
continued -