So some time ago, a friend of mine that I buy parts from, dangled this carrot in front of me:
Yes, that is a factory cable driven diesel tach setup from a 67-72 medium duty truck equipped with a Detroit. I very wisely passed on it for some time, but then I started having issues with my ISSPRO tach reading strangely. I'm not sure if it was a pickup problem or an actual tach head issue, but I would have been waaaaay bucks ahead to buy a whole new tach setup (or two), (or three), than convert to this tach setup. Anyway, I bought the tach cluster then proceeded to empty my wallet (a couple times over) getting it adapted to function in my truck and spend a huge amount of time tracking down parts for it (and cleaning that funk off the lens--that stuff was like a crackhead resisting an eviction notice).
After searching out a bunch of parts and having the tach head gone through and recalibrated by a speedo company that doesn't listen very well, I finally was able to assemble and install the converted cluster.
Astute observers will recognize the ammeter is no longer an ammeter. It is a converted volt meter and is made to look accurate for the cluster.
A close up of the gauge in operation:
Backside of the cluster showing the wiring for the volt meter conversion as well as the tach drive adapter. Ever wonder why the tach printed circuit had that strangely shaped hole in it?? Here's your answer:
In the end I found out the drive adapter is not needed for my application. It actually reverses the rotation making the tach try to read backwards. It sucks because it made the cable easier to attach. Oh well.
So a cable driven tach has no place to attach to a Cummins. The nice thing is, the Cummins B series has been used in so many different applications that it is only a matter of combining the correct parts to make a tach drive off the front of the motor where the original oil fill pipe used to reside:
Oh boy, a clearance issue with my GM fan on the Cummins. Goody. With some good old school file work, I was able to maximize the clearance between the fan and tach drive adapter:
I figured if the fan moves fore or aft, it would only move forward thus creating more clearance between the two components. It has been in there for over 10k with no issues so far and there has been some flogging along the way....
"Action" shot of the cluster:
So with the addition of the "factory" volt meter in the cluster, I was able to get rid of my aftermarket volt meter under the dash and with the factory tach I was able to get rid of my aftermarket tach up in my dash-top gauge pod. This allowed me to move my trans temp gauge up into my dash-top pod:
I also removed all of the crappy switches in my switch panel with Carling round bat toggle switches:
I like the look of the duckbill switches, but they were just junk.
I have been putting off making a panel for my coolant heater controls, so I took the opportunity to make a home for those as well:
I included a dual 2.1A USB charging port while I was at it.
So all in all it was a ridiculous amount of time and money completing this tach install. In the end, was it worth it?? Meh, who knows. It does look cool and that's all that matters, right??