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Fuel gauge for "Moon" type alum. gas tank?

14K views 20 replies 9 participants last post by  ericnova72 
#1 ·
Anyone ever seen a sending unit or fuel gauge for use with a spun aluminum fuel tank (pic of tank below)? I don't want to go to a lot of effort tying to adapt this tank for use with one of the normal bolt in sending units (plus I'm not even sure I could figure out how to use such a unit on my tank). Do most folks with these tanks just use the "yardstick" method of determining fuel level or is there some other simple trick for hooking up a fuel gauge of some sort?

 
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#3 ·
All after market sending units can be set up for different tank heights , the arm can be shortened and the float moved.
Another thought, how about a sight glass kinda of deal, like on a rear end.. Better then the yard stick, and would not require you to store your dipstick under the seat. Of course you would still have to get out of your hotrod to check it..
 
#4 ·
dinger said:
The gauge used on my old T was robbed from a 60's T-Bird. I believe Drake has an adjustable unit now.
How do those units fasten to the tank? Most that I've seen have a flat top on them that bolts to the top of the thank. But with the curve of the aluminum tank, I can't imagine how those bolt in units would work.
 
#5 ·
pepi said:
All after market sending units can be set up for different tank heights.... Another thought, how about a sight glass kinda of deal....
The tank height isn't the problem as I see it. The question is, how do you attach the unit to the tank. The tank is curved and the sender units I've seen are all made to mount flat on top of the tank. Also, I don't want to tear apart or cut into my tank unless I know for sure I can get something that will work. It's just not worth the risk to me to do a lot of experimentation trying to flog something to fit. I can live with just keeping track of my mileage for refueling...but just thought a gauge of some sort would really be convenient. I was hoping Moon or someone else made a nice, neat, easy to install sender for this exact application.

The sight glass idea might have worked well with the car in its original configuration (the photo in my first post). But that was just to show the tank I'm using. The tank has now been moved and tucked up under the pickup bed between the frame rails. There's no way I can see to affix a sight glass without it being very remote and very exposed...which I think would be a potential danger. But I'm open to suggestions if you see an alternative.

This is how the car is configured in its final version. The tank will be almost totally out of view.

 
#7 ·
35WINDOW said:
...I know this suggestion may be out there...
I like suggestions no matter HOW "out there" they might seem. Suggestions are meant to stimulate creative thinking...and that's what I need right now...a lot of creative thinking.

Those are some very nice looking sight glasses, but they all end up being sight glasses. So they raise a couple of problems. First is location. I really don't feel comfortable putting a unit like that inside the cockpit. Raises way too many issues with safety and appearance. And with the new location for my tank, I just can't come up with a spot where I could put a sight glass on the exterior of the car. I'm assuming the glass has to be installed even (level) with the tank in order to be accurate. Otherwise I might have been able to hide it somewhere inside the pickup bed. But the tank will be just below the the bed...so the sight glass has nowhere to hang from that I can see.
 
#8 ·
Instead of cutting your tank apart, can you fabricate a sending unit that inserts in through the filler neck? If there is room, maybe the filler hose could clamp to a whole new assembly that inserts into the tank (like a "Tee") and threads into place using the original threads intended for the fuel cap?

I love seeing that you built this rod from scratch! A little off-topin, but can I ask how you made the belt line? After looking at the first pic, I wondered how you added it...?

Thanks,
Gear
 
#9 ·
cboy said:
I like suggestions no matter HOW "out there" they might seem. Suggestions are meant to stimulate creative thinking...and that's what I need right now...a lot of creative thinking.
How Bout something like a boat or lawn mower, I have seen some tanks that have screw on filler caps with a float and a corkscrew for a gauge maybe something like that can be adapted to the filler of the tank. I will keep it in mind when I am strolling around the hardware store today.

Brian KC0KFG
 
#10 ·
Gear~head said:
Instead of cutting your tank apart, can you fabricate a sending unit that inserts in through the filler neck?
Hmmmm, now you've got me thinking. If the sending unit could somehow be mounted to a circle or ring that could be friction fit or pressure fit (maybe a steel ring with a slice cut out so you could compress it to fit in the filler hole) it would solve having to chop another large hole anywhere on the tank or figure out a flat spot for bolting it up. I'd also need to get the wiring in and out - but possibly that could be through a small hole drilled just to the side of the filler hole. It would have to be sealed up somehow.

Seems like some possibilities here. I'll have to look more closely at some of the sending units to see if I could adapt one to work with this idea. Thanks Gear...you got my brain cranking now.

Gear~head said:
...can I ask how you made the belt line?
Absolutely. It's one of my favorite topics. The belt line is made out of garden hose. Honest. It's the flat type sprinkler hose which turns out to be just about the right shape and height for belt line fabrication. Here are a couple of pictures of it being fabricated but just for your info, you can go to my journal here and see how the entire car was built...from early sketches through my current work sewing up the interior. And if you are interested in scratch built cars, you can also see my roadster being built here.

The hose.



Cut, shaped and contact cemented to the body.



A layer of fiberglass cloth applied over the top.



A bit of filler and some sanding.



And a dash of paint. Instant accent lines.

 
#11 ·
cboy said:
How do those units fasten to the tank? Most that I've seen have a flat top on them that bolts to the top of the thank. But with the curve of the aluminum tank, I can't imagine how those bolt in units would work.
Mine was next to the filler neck,the metal assembly epoxied on to the tank. It wasn't very pretty but it worked. It could have been prettied up but would have changed the look of the tank, I like the old style look. It was angled toward the body side so that much was not seen from the back.
 
#12 ·
cboy said:
Hmmmm, now you've got me thinking. If the sending unit could somehow be mounted to a circle or ring that could be friction fit or pressure fit (maybe a steel ring with a slice cut out so you could compress it to fit in the filler hole) it would solve having to chop another large hole anywhere on the tank or figure out a flat spot for bolting it up. I'd also need to get the wiring in and out - but possibly that could be through a small hole drilled just to the side of the filler hole. It would have to be sealed up somehow.

Seems like some possibilities here. I'll have to look more closely at some of the sending units to see if I could adapt one to work with this idea. Thanks Gear...you got my brain cranking now.

Lol...n/p. Looking at the pics again, you must fill your tank through the box floor? Your hieght availability must be totally limited. Is there enough room to weld on a small fitting so you can use a compressable grommet and nut to seal the wire(s) passing through it? I wonder if there is any electronic liquid level sensors you could insert. Something that didnt have a mechanical float....

Awesome idea, the lay flat hose is. Way cool! I'd love to build from scratch someday, but a rat rod with loads of rust & faded paint patina is really appealing to me lately. First I have to get my parts chaser done
 
#13 ·
Gear~head said:
Lol...n/p. Looking at the pics again, you must fill your tank through the box floor?
Exactly. And if I have the bed packed up for a long trip, I've got to remove stuff in order to fill the tank. I'll see how this works for a year or two and see if it is a big hassle or if it works out not to be a huge problem.
 
#15 ·
S10 Racer said:
... It looks like the top plate can be removed.
Sure looks like it to me too S10. It's hard to tell on some of the others (like this one from Speedway) exactly how the unit is attached to the top plate. But with the one you found it seems pretty clear to just be a bolt and then the wiring goes through the plate separately. And if that wiring pass through is easily removable, then all the parts and pieces are right there to cobble together something...just drill two holes in the tank near the filler hole, one to mount the unit and one to pass through the wire.

Thanks for the find.
 
#16 ·
After some more searching on the internet I ended up ordering this Sunpro unit which appears to have just one bolt through top plate with the wiring passing through that mounting point. I can't tell for absolute certain from the picture but I'm willing to take a shot since the price of this unit PLUS the gauge (with free shipping from Amazon) came out to be less than the Autometer sending unit alone from Pacific Customs. What further sold me was that the gauge (black face/black bezel) matches my other gauges.

I'll post an update after it arrives and I see exactly what I have to work with. My only concern now is getting the unit through my existing filler hole. It's going to be tight.

 
#17 ·
Why can't you cut the right size hole into the top on the tank, Then take the top plate of the sender unit, And make a new top plate that will be bent on the same curve of the tank, Bolt the sender unit to it, Drop it into the hole on the tank,, And bolt it on.. Make the curved plate a little bigger then the hole..And add a gasket.. ;)
 
#18 ·
NEW INTERIORS said:
Why can't you cut the right size hole into the top on the tank...
Primarily because I don't want to butcher this tank and have the fabrication fail for some reason. I'm just looking to limit my down side by drilling the smallest hole possible...something I can easily seal up should things go array. It's just not worth it to me to take any chances as all with the tank at this point...I'd rather use the mileage and yardstick routine.

Once the sending unit arrives I think I'll be able to figure out a fullproof approach.
 
#19 ·
The sender and fuel gauge arrived today so I couldn't resist checking it out. As seen in the first picture, the flat top plate comes off easily with the removal of the nuts on the center bolt.



So after seeing exactly what I had to work with, I determined that New Interiors had the right approach...hack a new hole in the top of the tank and use the existing top plate to attach the unit to the tank. Before cutting a hole, I wanted to make sure I could bend the plate and get it to conform to the curve of the tank.



I then took a very deep breath and attacked the tank with my hole saw. After cutting in the main hole, I drilled 5 holes for the self tapping screws (included with the sender).



I bolted the sender unit and bracket back onto the top plate, fished the unit through the hole, and bolted it down. I'll wait until I install the tank to set the final float height. BTW, the unit comes with a very good instruction sheet for setting the float based on the tank depth. I do, however, think the gauge will be somewhat deceptive between about 1/4 tank and empty, the reason being the shape of these tanks. The unit assumes a big flat tank with a uniform area at every height. But a moon tank obviously has much more area (cubic inches of fuel) at the half way mark than at either "full" or "empty". This will just become a matter of watching the gauge carefully and estimating the speed at which the remaining fuel will be used up. But still MUCH better than the yard stick routine.



Turned out to be a great little addition to the car. I got the sender AND a 2 1/4" fuel gauge that matched the rest of the gauges on my dash all for $30. The conversion was quite a bit easier than I was anticipating and a huge thank-you to all of you who kicked this one around and got me on track. It's going to be GREAT having an actual fuel gauge...very classy.
 
#20 ·
Look's very good Cboy... That's what I was trying to explain.. Came out very nice.. If Any one wanted to do this, You can also make two cap plates, One thicker one that you can tig on the tank,, And be able to drill in tap, Then cut out the center hole, Then drop in the unit, And you then have something to screw too.. But the way cboy did it will work find.. :thumbup:
 
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