Where do you get power for it? My other two guages are running off of the fan relay, but thats going to start possibly drawing too many amps, I don't know what the rating is on my Autometer tachometer, or on the other two(autometer and VDO).

Which wire do you hook the tach output to? The last time I installed one of these, it wasn't on an HEI distributor, and as I recall, the instructions didn't really cover an HEI ignition. There are a lot more wires now than the other setup. I'd like to leave the stock tach hooked up for reference to see how off it was.

Thanks for any tips. BTW, I got the big one, the 3 1/8 inch one. I decided if I had to look at it ever day, I didn't want to be straining my eyes. Hopefully I don't look too ricey.

 

I'm installing a tach right now myself. Mine needs a constant 12V source, probably to keep the shift light setting. I'm guessing the backlighting is triggered by the tach signal starting/stopping. I'll find out tonight!

Unless anybody has a better suggestion, I'm going to splice into the stereo power wire. I'll probably put a 1 Amp inline fuse on the tach side of this wire, but I really have no idea how much current it will draw. I could always adjust the fuse rating up and down until I find the limit. Don't have a DMM capable of measuring current. It can't be much though. Either way it won't be a major crisis if the stereo fuse blows, but I really don't think it will.

Unless you're running an MSD ignition box or something, all you'll have to do is run the tach wire directly to the "TACH" terminal on the distributor cap. The main thing is that your aftermarket tach doesn't need the stock tach's filter. In fact it probably can't read that signal. That's why you gotta get the signal right from the distributor. If you're wanting to run both tachs then I would make a little Y-shaped splice harness to go between both wires and the distributor terminal.

Where are you gonna mount that big tach? Top of the dash? My slightly smaller tach (every man is different :)) is going to sit on that ledge just in front of the leftmost vent. It won't fit on the steering column and I don't want to scar up the top dash pad cuz they're expensive. I'm going to use industrial Velcro so I'll be able to reposition if necessary.

 

Run the power wires to the fuse box in the cash. Run the light wire to the same fuse box and tap the light fuse. Run the groind wire to a groind point under the dash. Tap the tach wire under the dash where the multi-wire feed thru terminal brings the wires from under the hood the the inside of the car. If the vette is a L-98 you have a tach terminal on the distributor you can use.
Good luck. Sid.

 

Is there actually any way to add fuses to the fusebox? Otherwise I'll just splice into a different circuit and add a fuse.

 

Thanks for the replies. :) I got my Tach today, the 3 1/8 inch is way too big. So I'm going to send it back to trade for the 2 1/16. :(

My plan is to put it over the vents, on top of the dash. My dash pad isn't in that great of shape(no cracks, but faded), so this will give me a chance to recover it, while integrating the guages. I e-mailed Autometer a while ago suggesting that they make a guage pod that would mount on the dash, suggesting that Corvette drivers 1984-1990 would be very interested in it, and lots of older cars could use it too, like my 1984 Blazer and roomates 1964 Chevelle. I never got a return unfortunately.

After getting this big tach(I'm going to test this before I send it back), I was thinking of mounting it in the upper top right corner of the dash. I need to add two guages, the tach and oil pressure(I don't like having to switch between pressure and temperature). If I can fit them both snuggly in there, I may end up doing it. I've been playing around with sheet metal fabrication lately and I think I'm up to it.

That is a very good idea to use the stereo, thats probably what I'll end up doing, not the clock wire, but the one that comes on with the ignition. I don't have a shift light, my car is an automatic, and the governor is set up for 4,900 rpm shifts, with the transgo shift kit, I just pust the throttle down and the car does the rest.

Thanks again for the replies, they were very helpful, and I am no longer feeling as daunted by this installation.

:cheers: