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Installing a tachometer.

Posted: Thu Nov 17, 2011 4:23 pm
by dn29626
I found a guy selling an instrument cluster from a gasser for an 82 which includes a tachometer. What other parts are needed to get the tach to work on my 1982 720 diesel SD22?

Posted: Thu Nov 17, 2011 5:59 pm
by plenzen
Good luck with that.
I think there is a post on here someplace where Al Savage ( I think it was Al ) was able to get into the alternator and get something working through there. I believe that it will be "A project" from what I recall as there is no real place for the tach to pick up an impulse from the engine.

I think that some other people on here opted for the "Tiny Tach" that uses a small pickup mounted to the #1 injection line and that impulse is converted by some "black magic" box that comes with the tach and sent to a small digital display.

I recall that some of the people using the digital read out type find it a bit harder to read than the analog dial type. The numbers are small and the last 2 digits (10's and 1's) are constantly changing.

Keep us posted.


Posted: Thu Nov 17, 2011 8:09 pm
by dn29626
I am guessing then that no 720 with SD22 or SD25 came with a tach from the factory nor a dealership installation?
In short, nissan did not sell the parts for an OEM equivalent diesel install?

Posted: Fri Nov 18, 2011 6:15 am
by plenzen
You have me there Mr. That I do not know. Some of the LD's in the Maximas came with a tach and they were run from the alternator.
There is a casting place on the front timing cover of the SD's where a tach drive was installed but it was for a cable driven tach on marine and industrial use. I would assume that had there been a tach in the automotive application it too would have been run off the alternator, just not sure how it was done.


Posted: Fri Nov 18, 2011 6:23 pm
by Nissan_Ranger
There is a GM diesel powered Stewart-Stevenson aircraft power genset that uses the alternator as a signal source for the tach. The tach is a universal type with settable dips for different frequencies and alternator speeds. I'll get a name and P/N next week.


Posted: Mon Nov 21, 2011 4:16 pm
by Nissan_Ranger
Look at these.... ... pp=15&pg=8

They utilize signal from the stator...


here's a scheme to use a cheapo 4-6-8 gasser tach on diesel

Posted: Sat Feb 11, 2012 9:25 pm
by jiggseob ... ndex.shtml

its a bit of a project, but it does work

Posted: Sun Feb 12, 2012 6:55 am
by dn29626
Wow, what a read. Thanks.

Posted: Sat Oct 13, 2012 9:08 pm
by fieldtech
the sd22 did have a tach setup- very rare. the advance or "drivin" gear to the injection pump is where the mechanical cable was driven- I may have some pictures of one.

Posted: Sun Oct 14, 2012 5:58 am
by plenzen
That cable drive was on all the industrial/marine applications.

ASAIK any that showed up in automotive applications were driven from the Alt.


Posted: Sun Oct 14, 2012 7:03 am
by dn29626
All tach info is welcome.

Posted: Sun Oct 21, 2012 10:29 am
by Dale
This documents what i'm basically doing to mine: ... ndex.shtml

I'm planning on painting some white stripes on the crank pulley for now, may switch to the timing gear later if I have dirt issues too frequently. I'm using a circuit to amplify the photosensor to directly drive an analog tach.

Posted: Fri Jul 05, 2013 10:39 pm
by ehtrain
i got mine from tiny tach .com seems to work pretty good. my sd25 with 6mm lines. when super cold out out doesnt read rpms until fuel is warmer but other then that does its job

Posted: Sat Jul 06, 2013 7:51 am
by asavage
Long thread on this topic is the Diesel Tachometer thread, which is continued with lots more details in this thread. Summary from memory:
  • Tiny-Tach (for all diesels). Cheap (under $100). Uses injection line piezo pickup. Slow digital update (every .5 seconds). Works on all diesels that have external injector lines (ie all of our diesels).
  • Alternator tap (for all diesels). Modify the alternator to add one signal wire from the stator (pics of me doing this are in the thread) and use a diesel tach designed for alternator stator pickup signal -- in marine apps they're common. Not cheap but relatively easy. If your LD-series EGR Rev Sensor is bad and you get a good deal on a marine diesel tach (eBay, etc.), this is a good solution. I did this to my '82 Maxima Wagon.
  • EGR pickup mod (for LD series diesels). Modify the OEM EGR system controller to supply a std tach output signal. Detailed instructions in thread on how to mod the controller, or have one of us do it for you. Requires that the OEM EGR Rev Sensor is in working condition -- check it BEFORE modding the controller, they DO go bad. Use any std 6-cylinder tach. Relatively cheap and "sano".
  • Other stand-alone tach amplifier that uses the OEM EGR Rev Sensor. Details in that last thread. If it works for you, can be a bit cheaper than the EGR controller mod -- maybe. Best for engine transplant situations where you may not have an EGR controller to modify.

Re: Installing a tachometer.

Posted: Fri May 27, 2016 9:02 pm
by ecomike
My tinytach is working great on my frankenJeep's SD22. Thanks Al!!!