Tach for HZJ75 (Speedhut)

woytovich

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I'm zeroing in on adding some 24v versions of the Speedhut gauges for my Troopy. I currently have the basic cluster with only speedo, fuel and temp.
I am considering adding a tach and Speedhut has 2 flavors, one spec'd for diesel. I'm hoping someone knows enough about this to tell me which flavor is correct for this application.

Diesel tach
(Tachometer Signal Type: Diesel (alternator with an 'R' or 'W' terminal, crank sensor signal, magnetic pulse sensor)

or

standard tach
 

ATL Cruiser

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This is a really dumb question, but doesn't your truck have a tach already?
 

woytovich

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This is a really dumb question, but doesn't your truck have a tach already?
No. As I said up top speedo, fuel and temp is all I have.
 
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Driving without a Tach in my Troopy wasn't bad at all, but I wanted one. I ended up installing a Diesel spec'd TinyTach. Simple and relatively inexpensive. I don't look at it much now, but it was great when first installed to confirm HWY RPMs.

Photo from another mudder, and where I got the idea:

tiny tach bj75_01.jpg


Not that you are looking for install ideas, but one of the cleanest (to my eye) installs short of a cluster with tach is what @umpqua did- he mounted one in the air vent to the right of the steering wheel. Clean, innovative and unobtrusive.

70 Tach.jpeg



But to answer your query, I think you want the diesel tach. Here's a quick blurb from a stand alone AutoMeter gauge installed in an 1HZ powered 80, with a clean pillar mount.

 

Gun Runner 5

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No. As I said up top speedo, fuel and temp is all I have.
Just curious, in your previous vehicles that had tachs, assuming you had one, did you find yourself using it as a tool in day to day driving?
 

joekatana

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My bad, I see that now. I feel your pain. I cannot imagine not having a tachometer.
Powerband is from 1000 to 2800 rpm , not really that much need for a tach with a 1HZ . If you have a 2 stroke that runs 22000rpms with a power band between 16-18k a tach is handy when getting to know the engine but the 1HZ will let you know when it isn't happy by vibrations or getting to loud ;)
 
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the tach on my lj78 hasn’t worked properly since switching to a mechanical 3l injection pump.
It reads 1800 at 90kmh. Its not really a big deal since I use the speedo and engine noise for shifting.
I am poking around in the gauge to find a resistor or bridge clip to change that will bring the needle up to where it should be.
 

ATL Cruiser

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having a tach is nice, but feeling so strongly about it, i'm interested to hear why:popcorn:

ha! Maybe I worded that too strongly.

I used the tach a lot while tuning following the turbocharger / intercooler / boost compensator install. It helped a lot with that.

On a daily basis, the tachometer is fairly useless apart from being an idiot light. BUT it is pretty handy as an idiot light. For example, this morning, I noticed my RPM's had jumped from 650rpm to around 800rpm. I probably would have heard this eventually, but it was nice to catch on the tachometer. I had left A/C idle up tie rod loose during the multiple tunes and tweaks I've been doing. It had jammed up (hence the "idiot light"). Whoops. But the tach helped me there.
 

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