How to retrofit tachometer on Cummins 5.9?

[Elliot Naess]

Over the years, I have seen gauges that "float" randomly when the engine is off. Probably nothing to worry about if they work properly when the engine is running.

Some temperature gauges may simply show the present temperature no matter what -- just like the thermometer on the wall of your house. My pyrometer works that way. Right now it shows almost as much as the thermometer on my front porch. I'm not familiar with the pyrometer technology, but there is definitely NO normal 12 Volt wiring involved.

It would be the same with an old-fashioned "mechanical" temperature gauge, where the gauge-tube-and-sender is all in one sealed piece.

[WLDNWALT]

I need one of those Tachs for my bus, looks great.

[TopzyG]

Just ordered a photo tach to verify my 96 tc2000 tachometer. 42 inch tires 4.78 gear ratio mt643 transmission final gear ratio 1:1 tach reads 3,000 rpms at 55 mph, and idle 1,000.
I read somewhere that if the alternator was switched to a Delco that the cluster would have to be reprogrammed because the Delco pulses at a different rate. Bluebird in Glendale said that they can't do it.
Hopefully the tach is inaccurate in which case I'll install a magnetic pickup on the flywheel housing flywheel has 127 teeth according to 800-Cummins.

[gs1949]

Very interesting thread. Thanks for digging it up. I did not realize that some TC 2000s came without tachs. My 95 has an OEM tach. I think it is close enough for my purposes. It says my idle is about 1000 at first, but then after it's run a couple of minutes it slows down to a little less than 800.

I also have the 4.78 gears, but so far I have not driven it much.

[brokedown]

Originally Posted by TopzyG

Just ordered a photo tach to verify my 96 tc2000 tachometer. 42 inch tires 4.78 gear ratio mt643 transmission final gear ratio 1:1 tach reads 3,000 rpms at 55 mph, and idle 1,000.
I read somewhere that if the alternator was switched to a Delco that the cluster would have to be reprogrammed because the Delco pulses at a different rate. Bluebird in Glendale said that they can't do it.
Hopefully the tach is inaccurate in which case I'll install a magnetic pickup on the flywheel housing flywheel has 127 teeth according to 800-Cummins.

I haven't heard of difference in pulse rate... Generally it comes down to the size of the alternator pulley which translates into the gear ratio between the alternator and crankshaft. Your bus should idle around 650rpm and redline around 2600rpm.

[TopzyG]

Originally Posted by brokedown

I haven't heard of difference in pulse rate... Generally it comes down to the size of the alternator pulley which translates into the gear ratio between the alternator and crankshaft. Your bus should idle around 650rpm and redline around 2600rpm.

Really hoping it turns out to be an inaccurate tach. Did wide open throttle test, and two of the shifts are at 3,500. Either an inaccurate tach, or the previous owner church school pulled the P-pump and switched the governor springs?

[RMiller]

I just purchased a NOS tach for my 2003 thomas 5.9/3060 allison. The tach actually mounts in the rear of my gauge cluster with about a 1/4 turn and is a perfect match for the other gauges, the problem is I didn't receive any documents or installation instructions and it has a set of 8 and then 6 dip switches and I have no idea how they should be set. The tach is a panelltronics pn 103-003. anyone have one installed that could maybe get a picture of how the dips are set? or maybe instructions? Thanks