MG Car Repair: Fuel sending unit, rectangle shape, screw holes

Question
QUESTION: Hello Howard,
I recently purchased a new fuel sending unit for a 1964 MGB. My problem is the new sending unit doesn't fit into the old sending unit hole. I made sure that I purchased the sending unit that matches with fuel gauge. I even filled down the unit to the point where I filled through the sending unit. After breaking the sending unit I tried to fit the device in the hole and it still wont fit. If you could give me any advice I would really appreciate it.

Thank You

ANSWER: Hi Chad,
What don't fit about the sending unit? Is the diameter of the steel round plate not correct? The early tanks had the unit secured by screws and the later tanks had a ring that was rotated to secure the unit. Which does your tank have?
Let me know.
Howard

---------- FOLLOW-UP ----------

QUESTION: This is a early tank so the sending unit is screwed to the tank. The Diameter of the new sending unit is what is causing the the unit not to fit. The sending unit looks completely different from the original. The old unit is a rectangle shape device and the new unit is more round. I hope this information helps out.

Thank You

Answer
Chad, the mounting surface should be flat with threaded holes to mount the new unit. If the screw holes match up then it is correct, if the screw holes don't match up then it is the wrong unit. The original unit was rectangle unit on a round mounting plate and that is the complete unit. The round mounting plate is all that needs to be correct. Do the screw holes around the mounting part match? If not, you have the wrong unit. There may be tabs that match up to notches in the tank so you don't install it up-side down. just feed the float into the tank and align the tab or tabs with the notch or notches in the tank hole and with a new gasket in place put the screws in around the round plate and you are done. It doesn't matter what the unit looks like as long as the mounting plate screws fit and the tab or tabs line up in the inner part of the tank and mounting plate. The mounting plate is on a flat surface so it does not matter what diameter the plate is as long as the inner tab line up and the screws line up.
Let me know.
Howard