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Tach/fuel combo gauge -- install, review, pics

I have dual tanks. I did not like the idea of switching the gauges with the fuel tank selector. Seems like a recipe for running out of gas to me. (For you aviation buffs, cf. Stinson Station Wagon.)

So I mounted a second fuel gauge in the empty position. This position would take the clock, or, if you got a tach, it would take a small fuel gauge instead of the big honking one next to the speedometer. So, there's a small fuel gauge made that fits into that position, and with a little work, you can put a second fuel gauge there, which I did. Two tanks, two gauges. Perfect.

Having a tach would be nice, though. So when I heard about the combination tach/fuel gauge from the larger trucks that used the C/K cab, that was cool. Sure, it went into a different basket, but the basket could be modded, just like I modded the basket to take the small fuel gauge in the empty position.

Even better was when I heard about a tach/fuel combo gauge that fit directly into the stock C/K basket. I installed it yesterday. Total elapsed time: 5-1/2 hours. Results: Excellent.

The dashboard was disassembled in the usual fashion, with all the usual hassles. Getting the headlight knob-and-stick out was annoying. The radio removal from the one-DIN shell was easy, removing the instrument bezel with the one-DIN shell installed was a pain. Removal of the other items necessary to remove the instrument basket was straightforward.

The instrument basket has to be modified to fir the new gauge. The fuel gauge mechanism fits where the shrouds for the "fasten your seat belt" and "brake" warning lights go, so the center part of the shrouds have to be cut out of the basket. After removing the warning light bulbs, a little work with a Dremel tool accomplished this. The divider between the two warning light shrouds has to be shaved right down to the bottom wall of the basket. Also, the bosses that hold the locating pins on either side of the shrouds have to be shaved down a touch.

The gauge sits so deep in the basket that the three pins that make the fuel gauge connections go right through the spring clip holes and stick out the other side. The spring clips are too tall inside the basket to let the gauge fit all the way down where it needs to be. I removed the spring clips and bent the upper portion of the spring clips (the parts that flare back out) out horizontally. I reinstalled the clips, fit the gauge into the basket, and fastened the gauge into the basket with nuts on the three terminal bolts.

The gauge mounting tabs have some flash or something on them that gives them an L or U cross-section, like a flange along the side(s) of the tabs. See picture. These must be removed for the gauge mask and lens to mount flush in their original position. I clipped them off with side cutters.

To restore a brake warning light, I cut the warning light lenses and created a new lens for the speedometer warning light locations from the pieces. The warning light lenses have the legends, plus a dark wide bar between positions: 4WD LOCK|CHOKE and FASTEN SEAT BELTS|BRAKE. I cut them with scissors along one side of the heavy dividing line so I had 4WDLOCK| and |BRAKE. I then overlay the heavy line of one over the heavy line of the other and secured with plastic styrene cement, so I had 4WD LOCK|BRAKE. You also need to cut a locating pin hole in the CHOKE side, because the locating pins are in different locations so you don't put the lenses in on the wrong side.

To get the BRAKE warning light to work, I removed the BRAKE warning light socket and the CHOKE warning light socket. Looking at the circuit board, you will see that these two lamps have one terminal in common already, the ignition trace. I soldered a small wire from the back side of the contact ear on one socket to the back side of the contact ear on the other socket, and replaced both sockets in the panel so the connected ears were in contact with the non-common terminals of those two positions. Basically, I bridged the two warning light positions to each other.

I then removed the FASTEN SEAT BELTS warning light socket and ran the tach wire out the back side of the basket through this hole.

Re-installation of the dashboard was straightforward and typically annoying.

I did not connect the provided wire directly to the distributor TACH connection. Instead I ran a new wire (had some per spec BROWN wire in stock) for the distributor connection so that I could have some service loop and a disconnect behind the dash. One crimp female for the distributor connection, and a male-female crimp disconnect set for the connection of my new wire to the provided wire behind the dash. I ran the wire from the distributor along the harness and then through the grommet that passes the speedometer cable. I left enough on each wire to do the crimp connection below the dashboard and tucked the extra wire up behind the dash.

To check tachometer function, I read the engine speed on idle with the timing light's rpm function and compared it to the tach reading. The tach is dead on as delivered. The new fuel gauge also gave the same reading (it was on about 1/4 tank when I did the install) as the old gauge did.

Here is the gauge side view. Note fuel gauge mechanism location; this is what requires removing the warning light shrouds. Note also the flange on one of the mounting tabs seen here. They all have some rubbery/plasticy flash on them that needs to be removed. The three mounting tabs must be simple metal tabs sticking out from the gauge, nothing more, either in thickness or in flange-like flash along the edges.

Before.

After.

(on the phone with the internet provider because I am having trouble uploading pictures right now. Pictures soon, I just don't want this window to time out!)