Installing tachometer
Logistics Pro
Joined: Sep 2014
Posts: 4,920
Likes: 21
From: Bothell & Silverdale, WA
Wow! The second one is a beautiful instrument cluster.
My original speedometer works. Gas gauge does not. I put new tank and new 6 volt sending unit. How do I check if it is the gauge or the sending unit. Maybe I do not have power to the cluster. The high beam indicator works can’t remember off the top of my head but pretty sure oil pressure gauge works. Haven’t had it running enough to move temp gauge. Don’t seem to remember the voltmeter working either.
-11 out, too cold to go work in the garage.
My original speedometer works. Gas gauge does not. I put new tank and new 6 volt sending unit. How do I check if it is the gauge or the sending unit. Maybe I do not have power to the cluster. The high beam indicator works can’t remember off the top of my head but pretty sure oil pressure gauge works. Haven’t had it running enough to move temp gauge. Don’t seem to remember the voltmeter working either.
-11 out, too cold to go work in the garage.
If you decide to go with 12 volts it can be accomplished relatively inexpensively with no rewiring involved. 1) You do not have to use an alternator. You can simply replace your 6 volt generator with a 12 volt generator from a later year, and same for the voltage regulator (get them at a salvage yard cheap), and you can keep all of your original wiring and switches, horn, starter relay, and starter (except for reversing the wire that goes through the ammeter loop, if you go with negative ground). 2) You can sort out your gauge issues and use a voltage reducer for them (works great). 3) The only obvious things that will have to be replaced is the battery and all of the light bulbs. This will keep you semi-purist, but going 12 volts will open up a whole new world of options. If you have 6 volt electric wipers and heater motor you can get voltage reducers for them also.
Fleet Mechanic
Joined: Sep 2010
Posts: 1,834
Likes: 467
From: Mason City, Iowa
Another way of testing the gas gauge is temporarily short out the fuel level sender wire to ground at its connection point at the tank but do not ground it on the tank. Use another metal ground point. If the gauge sweeps all the way to Full you know the gauge is powered and wiring to the tank is good. Next check to make sure the tank has a good ground connection between the sender flange and again a good metal ground point. If you have a missing ground there the gauge may not work. If the tests above are good then you probably have a bad sender in the tank. Hope that helps!
Lead Driver
Joined: Nov 2002
Posts: 9,686
Likes: 1,255
From: Jefferson City, MO
Fleet Mechanic
Joined: Jan 2007
Posts: 1,847
Likes: 37
From: Eastern shore,Salisbur,MD
Believe it or not, I had a mechanical tach on my Fire truck that was originally a 6volt truck. It ran off the transmission, via a speedometer type cable to the pump panel. The truck pumped in 4th gear.
Fleet Mechanic
Joined: Mar 2005
Posts: 1,462
Likes: 185
From: Dedham, MA
I guess if the transmission ration is 1:1 in 4th gear, it would be accurate of engine RPM. I have seen the mechanical ones driven from distributors, but that would require some shnazzy adapter or customizing to a stock dizzy.
Senior User
Joined: Feb 2011
Posts: 298
Likes: 1
From: Huntsville, Al
There are numerous threads on many of the forums (Ford Barn, H.A.M.B., Studebaker and Stovebolt forums ) that discuss this subject. If in fact you wish to continue to use the 6 volt + ground system the best bet is to go with the Westach gauge (Westach) . Early versions of tachometers were Cable driven. Tractors, Allis Chalmers come to mind, and early Corvette's (55 -61) were driven off the generator, although the rear drive assembly for the generator on the Corvette is upwards of $200 alone and of course then there's the expense of the generator itself (6 v + ground ). One member on the Ford Barn site developed an inverter for a 6volt tach but I believe his expense for production quality and quantity was at or near $130 per unit.
I found it much easier and less expensive to convert to 12 v Neg ground on my vehicles.
I found it much easier and less expensive to convert to 12 v Neg ground on my vehicles.
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Fleet Mechanic
Joined: Jan 2007
Posts: 1,847
Likes: 37
From: Eastern shore,Salisbur,MD
When I was re-wiring the truck , I took a 12 v battery from a toy car that the grandkids drove. It was light , portable and was used to test circuits without fireing up the whole fuse pannel. Was very handy. I will look for a picture of my gas gauge test
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