Author Topic: Tach/fuel combo gauge -- install, review, pics  (Read 13795 times)

Offline rich weyand

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Tach/fuel combo gauge -- install, review, pics
« on: May 18, 2014, 12:38:45 AM »
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. This tach/fuel combo gauge is available from http://www.gmsports.com. My understanding is that they have this gauge built semi-custom for them, so it is not available anywhere else. Shipping was next day and billing against my card was correct.  This is the item.  http://www.gmsports.com/content/new-tachometer-1973-1986-chevy-and-gmc-trucks.  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.

« Last Edit: May 18, 2014, 11:18:41 AM by rich weyand »
Rich

"Working Girl": 1978 K-10 RCSB 350/TH350/NP203 +2/+3 Tuff Country lift

Offline bake74

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Re: Tach/fuel combo gauge -- install, review, pics
« Reply #1 on: May 18, 2014, 09:49:16 AM »
     Very nicely done, your link "to the item" does not work though, it says "page not found".
#1: The easiest and most obvious solution to any problem is 99% of the time correct.
#2: There is no such thing as impossible, it just takes longer.
  74 k10, 77k10    Tom

Offline sbx22

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Re: Tach/fuel combo gauge -- install, review, pics
« Reply #2 on: May 18, 2014, 09:55:02 AM »
That looks awesome, functions even better. Nice writeup.

Offline rich weyand

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Re: Tach/fuel combo gauge -- install, review, pics
« Reply #3 on: May 18, 2014, 11:19:52 AM »
     Very nicely done, your link "to the item" does not work though, it says "page not found".

Fixed in the OP.
Rich

"Working Girl": 1978 K-10 RCSB 350/TH350/NP203 +2/+3 Tuff Country lift

Offline rich weyand

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Re: Tach/fuel combo gauge -- install, review, pics
« Reply #4 on: May 18, 2014, 11:22:00 AM »
That looks awesome, functions even better. Nice writeup.

Thanks!  Couple hundred bucks and 5-1/2 hours work, but I think it was well worth it.
Rich

"Working Girl": 1978 K-10 RCSB 350/TH350/NP203 +2/+3 Tuff Country lift

Offline KWKENUF

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Re: Tach/fuel combo gauge -- install, review, pics
« Reply #5 on: May 21, 2014, 08:41:45 AM »
Awesome!  You are the second person I know of to do this,  and both had great results!

Personally I don't like that the fonts are different.  My OCD prevents me from doing this mod because of it.

Gonna do intermittent wipers?!

Offline rich weyand

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Re: Tach/fuel combo gauge -- install, review, pics
« Reply #6 on: May 21, 2014, 10:01:38 AM »
Awesome!  You are the second person I know of to do this,  and both had great results!

Personally I don't like that the fonts are different.  My OCD prevents me from doing this mod because of it.

Gonna do intermittent wipers?!

I have OCD and ADD, so everything has to be perfect, but only for a short time.

Before you do intermittent wipers, read this.
http://forum.73-87chevytrucks.com/smforum/index.php?topic=27235.0
Rich

"Working Girl": 1978 K-10 RCSB 350/TH350/NP203 +2/+3 Tuff Country lift

Offline zieg85

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Re: Tach/fuel combo gauge -- install, review, pics
« Reply #7 on: May 21, 2014, 12:19:38 PM »
I like the intermittent wiper write up.  Does that mean no constant lo and only hi on the switch?
1985 C30 Custom Deluxe Ext. cab 5.7L TH400 3.21 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction
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Offline rich weyand

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Re: Tach/fuel combo gauge -- install, review, pics
« Reply #8 on: May 21, 2014, 12:45:59 PM »
No, the wiper switch works completely normally.  All the button does is short the parking cam wires so the wipers don't think they are parked whenever the button is held down.  You can push it down as often as you want, whenever you want, for as long as you want, or just hold it down continuously, and the wipers will run whenever it is held down.  When the dash switch is in either LO or HI, pushing the button has no effect.
Rich

"Working Girl": 1978 K-10 RCSB 350/TH350/NP203 +2/+3 Tuff Country lift

Offline zieg85

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Re: Tach/fuel combo gauge -- install, review, pics
« Reply #9 on: May 21, 2014, 06:39:17 PM »
No, the wiper switch works completely normally.  All the button does is short the parking cam wires so the wipers don't think they are parked whenever the button is held down.  You can push it down as often as you want, whenever you want, for as long as you want, or just hold it down continuously, and the wipers will run whenever it is held down.  When the dash switch is in either LO or HI, pushing the button has no effect.
Excellent, you are my go to guy when I do this for my 1985.  I will of course need help with what wires I need to access with the column mounted wiper switch.
1985 C30 Custom Deluxe Ext. cab 5.7L TH400 3.21 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction
https://www.facebook.com/groups/248658382003506/

Offline rich weyand

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Re: Tach/fuel combo gauge -- install, review, pics
« Reply #10 on: May 21, 2014, 08:09:50 PM »
Just follow the two wires from the park switch (PARK SW) on this diagram, circuits 91 (GRAY) and 97 (BLK/LT BLU), and pick them up on the inside of the cab behind the instrument panel.  Run jumpers from those two wires down to the switch.  When you push the button, the wipers will run in LO, thinking they need to park.  This will not affect any other operation, even if you push the button when the wipers are already on, whether in HI or LO.  When you release the button, the wipers will park normally.

http://www.73-87chevytrucks.com/techinfo/wiring_diagrams/81-87_V8_engine.jpg
Rich

"Working Girl": 1978 K-10 RCSB 350/TH350/NP203 +2/+3 Tuff Country lift

Offline KWKENUF

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Re: Tach/fuel combo gauge -- install, review, pics
« Reply #11 on: May 21, 2014, 09:56:33 PM »
I have OCD and ADD, so everything has to be perfect, but only for a short time.

Before you do intermittent wipers, read this.
http://forum.73-87chevytrucks.com/smforum/index.php?topic=27235.0

I saw that write-up but never actually read it.  I went the other route and got the module and switch.

On a side note,  I am prepping a tach cluster to go in my 79.  I kinda wish I had the later style font so I could do the dual gas tank gauges like you have,  with the tach you have.  But,  everything I am doing seems to be in motion before you do your thing!

BTW...  Love the truck Rich!

Offline rich weyand

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Re: Tach/fuel combo gauge -- install, review, pics
« Reply #12 on: May 22, 2014, 12:15:13 AM »
I have OCD and ADD, so everything has to be perfect, but only for a short time.

Before you do intermittent wipers, read this.
http://forum.73-87chevytrucks.com/smforum/index.php?topic=27235.0

I saw that write-up but never actually read it.  I went the other route and got the module and switch.

On a side note,  I am prepping a tach cluster to go in my 79.  I kinda wish I had the later style font so I could do the dual gas tank gauges like you have,  with the tach you have.  But,  everything I am doing seems to be in motion before you do your thing!

BTW...  Love the truck Rich!

Thanks, I do, too!  Couple things:

- You can still do the floor button in addition to the intermittent module.  It is really nice to be able to just step on it and get wipers right now, and fumble for and turn on the dash switch when you get the chance.  Some pretty twisty roads around here, and when the rain starts, you can be busy.  Anyway, the action of the intermittent module will be unaffected, because all the floor switch does is tell the wipers that they aren't parked.

- You can also still do the dual fuel gauges.  Get the gauge from gmsports.com, and then wire the supply terminals on the fuel gauge to the small fuel gauge on the left, hook up the extra sender wire to the gauge, and hook up the distributor wire to the tach.  This is cleaner than what I did, because the tach cluster already has the bosses for the small fuel gauge.  Either that or you could use the combo tach/fuel from that mail-order outfit with the three initials, which is cheaper because it does not move the fuel gauge terminals to the center of the unit, which you don't need if you have the tach cluster.

Since I don't get my write-ups done in time for your efforts, I'll give you some advance notice!  Next on my agenda is paint.  I have some rust coming through in all the usual places on the bed, so I am going to build up a completely new bed and sell off the old one.  Every single panel is available in galvanized, which will solve that problem forever.  Also, every single piece of hardware is available for the tailgate.  New lights will be Altezza style, but with a black backing plate, not chrome/silver, which ought to look pretty cool on a black truck, and will finally give me some decent back-up lights where I can see something.  New paint will be black also, and pin strip will be red to pick up the interior.  I saw a black 1967 4-4-2 with red interior and red pinstripe at Mecum last week, and it really works.  I will also shave the badges and the drip rails, and remove the window shades and maybe the fender outline trim.
Rich

"Working Girl": 1978 K-10 RCSB 350/TH350/NP203 +2/+3 Tuff Country lift