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I'm always harping on ground issues because power in a wire can go nowhere unless it has a return path. This is just a reminder... 12-volts is very easy to insulate and sometimes we do it without realizing. I use teflon tape on just about all pipe threads, but in this case it might get you in trouble.
Oil pressure and temperature senders require a good ground connection through the threads that go into the engine's ground. These senders have pipe threads that are tapered and should self-seal. Using sealer on the threads can cause the sender to have a bad ground connection, causing a gauge to not work or read lower than it should. If absolutely necessary to stop a leak, a very small amount of liquid sealant may be used on part of the sender threads and should not cause a problem with gauge accuracy.
Fuel tanks are commonly grounded very poorly, especially if the restorer used good paint or undercoating on the tank, car body, or straps. I drill a small hole in the unused corner of the tank, a safe distance from the seam weld, then I bolt a separate ground wire to the car body. You can get fancy and use stainless or brass bolts but good bonding comes from using a stranded copper wire (#16 or heavier) crimped-on a ring terminal, lock washer, bolt and nut. Your 6-volt fuel gauge will work much more accurately. - Dave
Oil pressure and temperature senders require a good ground connection through the threads that go into the engine's ground. These senders have pipe threads that are tapered and should self-seal. Using sealer on the threads can cause the sender to have a bad ground connection, causing a gauge to not work or read lower than it should. If absolutely necessary to stop a leak, a very small amount of liquid sealant may be used on part of the sender threads and should not cause a problem with gauge accuracy.
Fuel tanks are commonly grounded very poorly, especially if the restorer used good paint or undercoating on the tank, car body, or straps. I drill a small hole in the unused corner of the tank, a safe distance from the seam weld, then I bolt a separate ground wire to the car body. You can get fancy and use stainless or brass bolts but good bonding comes from using a stranded copper wire (#16 or heavier) crimped-on a ring terminal, lock washer, bolt and nut. Your 6-volt fuel gauge will work much more accurately. - Dave