The Cessna 120-140 Association Forum

When I bought my 120, there had been 2 new fuel gauges installed. The seller said that somehow what was installed had the wrong float arm length so the net effect is the float hits the top of the tank when full but the gauge doesn't read more than 3/4. It reads completely accurate as you burn fuel and get to the point where the float can move down.

So, is there a way to adjust the scale on the travel range of the float? I also have the old set of gauges that were removed, does anyone overhaul those?

Looking for some thoughts. My mechanic says it's fine as long as it correctly reads empty which is does but it's a bit annoying.

Thanks

If the gauge reads from empty to 3/4 as the tank goes from empty to full, the arm is too long. You could probably bend it in a zig-zag pattern to effectively shorten it. Just go a little at a time. Any correction on the top will also happen on the bottom, so you'll have to change the angle of the arm, too, to keep it accurate at the bottom.

There are only two requirements with respect to accuracy:
1) When the tank is empty, the gauge must say "Empty".
2) If the gauge says full, the tank must be full.

Note that a gauge that always reads "Empty" meets these conditions...

The throw from the pivot point of the gauge to the center of the cork measures 4" on mine. The replacement Rochester gauges seem to have a real long throw.

there's not much to rebuild. you can get new synthetic floats from spruce, make new gaskets yourself. or you can try bending the arms. or be thankful they read accurately near the bottom end, that is what's important

I have not confirmed this, but I've been told that these gauges are also used for propane tanks and a place that services them will have parts.

Thanks for all of the feedback!

I took a couple of pics of the old ones. I assume I need to mimic this with the bends on the float arms?

Yes, assuming the gears are the same, the distance from the pivot point to the center of the float needs to be the same. (Looks like 3 1/2")

About 4" on the example I have