Right Tank Float Sender

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Turns out, I spent 1.5 hours in the shop tonight, but it felt a lot shorter, and I feel like things are going really slowly. I passed 40 hours on the tanks (right tank) today, and while I know the left weill take significantly less time, I’m
still nervous that by the time I finish the right and then start and finish the left, it’ll be 100 hours.


Okay, before dinner, I pulled out the baffle, the spare access cover, and the hardware called out for the sender attachment.

K100-8 nutplates and AN515-8R8 machine screws.

I final-eyeballed the center of the tank and a vertical alignment (same eyeballing you would have done on the inboard rib, so I’m safe here), and put some #40 holes in the baffle.

#40s drilled.

Then, I spent some time trying to figure out what size hole I needed in the baffles for the #8 screw. After some internet searching, I put together this little table.

Clearance Hole Drill
Mach. Screw Size TPI Close Fit Free Fit
# Major Dia. (in) TPI Drill Size Dec. Eq. Drill Size Dec. Eq.
4 0.112 40/48 32 0.116 30 0.1285
6 0.138 32/40 27 0.144 25 0.1495
8 0.164 32/36 18 0.1695 16 0.177
10 0.19 24 9 0.196 7 0.201

This is still a little confusing to me. I don’t have any of these drill sizes. I stuck a #19 drill in the prepunched spare access cover, and it was pretty much what I would call a loose fit. Also, I can oversize the hole a little, because the hole in the baffle doesn’t matter, The hole in the nutplate does. So

And ANOTHER thing. I remember drilling some of the “to-be-dimpled”
skins to #19 for a #8 dimple die (which kind of makes sense given the dimple opening up the hole a little.)

Next, I used a 1 inch hole saw to cut an undersized hole (didn’t have a closer size) and spent a good 20 minutes with the dremel and a rotary file to get a nice round hole for the sender.


Nice, part deux.

Then, a few turns with the countersink, and I used some oops rivets to attach the K1000-8 nutplates in place. Oh, one more thing. Make sure you don’t just blindly use the same rivet callouts they tell you to for the plate in this location. They said AN426AD3-4, so I used the Oops rivet -4s. Too long. I bent a couple rivet heads over and they cracked.

Had to (successfully) drill two out. (Why can’t I get my average above 7%!?)

Anyway, they look good now.

Good. Not great.

Just for kicks, I bolted the sender in (without the supplied

And then I set it on the tank so you could see that I installed it in the second bay (so it doesn’t interfere with the flop tube in the first bay).

Floats and flop tubes don't mix.

I should have named the post “floats and flop tubes don’t mix.”

1.5 hours, 10 rivets set. Three drilled out.

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