Fuel sending unit install????????????????

[BIG CHEVY 3600]

I am ready to install the gas tank sending unit. It is a Classic Gauges product and after reading the directions I am confused. It tells me to cut a 1 5/8 Hole in the tank and then insert the unit into the tank and then attach it using the 5 screws provided into the "pre-drilled holes". What pre-drilled holes? The directions to this point does not mention drilling holes. Besides it looks like the screws need a threaded hole. Anyone know how this all works?

[OrrieG]

Stock tank or aftermarket. There is a standard pattern for fuel sending units. If you bought an aftermarket tank it should have came with a standard fitting for the sender. Sounds like you have something that was made without the sending unit plate. The fitting is about 1/8" thick so it will not deflect and will seal tight. The sending unit is attached with 5 machine screws and a gasket. . Don't use sheetmetal screws on the thinner guage tank, you will have a hard time with the metal oil canning and leaking and the screws possibly backing out.

[BIG CHEVY 3600]

Originally Posted by OrrieG

Stock tank or aftermarket. There is a standard pattern for fuel sending units. If you bought an aftermarket tank it should have came with a standard fitting for the sender. Sounds like you have something that was made without the sending unit plate. The fitting is about 1/8" thick so it will not deflect and will seal tight. The sending unit is attached with 5 machine screws and a gasket. . Don't use sheetmetal screws on the thinner guage tank, you will have a hard time with the metal oil canning and leaking and the screws possibly backing out.

OK so what do I do to attached the sending unit if it came without this plate?
http://good-times.webshots.com/photo...99708909ITmsUH

As you can see the tank came with two outlets, one inlet, and a vent.

[Gene Sharp]

What I would do IF the tank has not yet had gas in it would be to take it to a good sheet metal shop along with the guage and get a plate made to fit the guage with big hole and bolt holes ,,,,,,,,,then drill matching holes in your tank and get it welded on
would probably be lots quicker than trying to rreturn tank and you get to put sender where ever you want

Gene Sharp

[55dude]

time to get on the phone with classic gauges and have them clear up your confusion. most sending units "bolt in" with or without adaptor supplied. never heard of anyone having to cut their tank to install one.

[mr48chev]

Most aftermarket sending units have to have the hole cut for them and you have to "predrill" the screw holes for the mounting screws your self.

It is imperative that you get the screw holes in the exact positions that they need to be in an they need to be the correct size for the supplied screws to fit tightly.
There should be plenty of charts on the net and in manuals that show exactly which size of drill bit to use with the particular sheet metal screw. Also I would suggest using a good quality an new drill bit so it doesn't walk on the tanks metal.e l

On last thing is to make sure that the sending unit is placed so that the arm on the float doesn't come in contact with the side of the tank, baffles or other obstructions.

[BIG CHEVY 3600]

Originally Posted by mr48chev

Also I would suggest using a good quality an new drill bit so it doesn't walk on the tanks metal.

Great suggestion. I think I'll use the screws that came with the sender. They have rubber washers on them. That means I'll need to tap the holes. The aluminum is 1/8" so should hold the tap. The screws are 10 32.