Ok, So I bought the autometer alternator tach ( 2-5/8" sport comp diesel) and I have it all hooked up except for the 12 volt ignition wire. Where can I find the wire/fuse to tap into? I already have the 1 amp fuse on there (what the instructions said) so this is the only thing holding me back.

Also it said that I'm going to need to calibrate the tach. It also said to do this at highway RPM instead of idle rpm. How would I go about doing this? Theres a little allen key on the back of the tach that allows me to remove the cover and turn some **** to calibrate it. So Im guessin that I need to get some sort of rpm light thing that I point at the crank and then calibrate the tach from there?

Thanks

Lucas

 

I used a fuse tap off the power windows. That's a 30 amp circuit that's only hot with the key on.

You can use an optical tach, if you know somebody with a scanner you can get an RPM reading off the PCM ('92 and '93 only), or you can do the math and set it off the speedo.

 

Thanks Dave.

I got it all hooked up and it works fairly well. At idle and with the key on (motor not running) the needle "vibrates" so to speak, kind of bouncing around. I'm guessing this is electrical interference? The probe wires are next to my pyro probe wires so maybe this is whats causing it?

I calibrated it to what I think is correct. After a quick test drive, I notice that the motor seems to rev slower (according to the tach) that what I thought originally. Maybe I'm just too used to a gasser with quick, resposive RPMs versus a big diesel with a super sluggish turbo .

 

I used a optical tach I borrowed from my brother who flies RC airplanes. I put two reflective strips on my harmonic balancer (simulate a 2 bladed prop) and used a couple of tiewraps to rev the engine up to about 3000 and hold steady. Then I just pointed the tach at the HB and got the reading and calibrated the tach.

I had set it by guesswork like you did and I discovered it was way off so it's definately worth the effort to do it correctly.

Edwin

 

Mine does the same thing. I've heard others mention it to. I guess it's becuase there is no signal being produced and it's sitting next to an magnetic field

Den

 

somwhere between 6-700 rpms the drivers mirror shakes if that helps, LOL. it works. or is stock you can guess the defueling point.....