I'll being installing a new gas tank and sender unit in my '69 tomorrow morning. How much gas do I need to put in to get a 1/2 tank reading?

I have checked the ohm readings on the sender. The sender reads 0 ohms at full drop and 94 ohms at full raised position. I just want to verify that the gauge is reading accurately. I'm prepared to realign the needle if needed.
If I do need to adjust the needle I think the 1/2 mark would be easiest.

It should about 65 degrees tomorrow in Vacaville.

How much gas?

Tank is 18 gallons full, so half a tank by volume is 9 gallons.

Thanks Mark. I wasn't sure since you can never get the tank completely full. If the tank is completely empty can you get 18 gallons in it or is more like 16 1/2 gallons?

thanks,

Gas gauges are more like "guidlines" than they are accurate instruments.

Fred,

Have you thought about just hooking the sending unit up by itself with the ground attached. Then figure out where the half way mark is and see where the guage reads.

Like Dnult said it is used for reference. At least you could get a general idea of the 1/2 mark. You also will be able to check the empty and full marks.

I put in 9 gallons and got 3/8th of a tank reading on the gauge. I'm still thinking about resetting the needle.

I will change location of the ground @ the back of the tank first. There is a lot of undercoating and general dirt in that area. I'll find a good clean spot on the underbody or rear frame rail.

Personally, I'd fill the tank and go from there. Mental note of gas added, then when indicating 1/2 tank, fill it and compare with original volume added. Seems to me capacity is 16 gallons.

As said, its not an exact science, just an indicator.

Even my 2002 Camaro uses the last half the tank faster than the first. Seems I can drive for 2 or 3 days between 1/4 marks on the upper half, but when I get below 1/4, it's time to fill up. I don't think you'll find too many cars on the road that accurately gauge the fuel in the tank.

I ran into a bubby of mine this afternoon.( He had a similar issue with his '67 Elko.) I told him of my morning tank install and the way the gauge was reading. He gave me a resistor to put inline on the tan wire in the trunk. I did this mod. this evening. The gauge now reads 1/2 tank with 9 gallons of gas.

I think I'm as close as i will get. I didn't read the stripes on the resistor so I don't know what it's value is, Sorry :(

Thanks for all the tips,

Good info...

Drain the tank and see if you ever hit "E". Now that you've added a resistance to the circuit you might not make it.

This morning I pumped out 5 gallons of gas to see where that put the gauge. The gauge went down to just hair above empty. So at that point I should have 4 gallons of gas left in the tank. Hmmm... I refilled the tank with the 5 gallons I took out. Gauge is back to 1/2 tank.

I drove a mile and filled the tank. With a full tank the gauge is now pegged past the full mark.

This should be enough reference to keep me out of trouble.