Got good news for you john... the tach setup that you describe (all coil input current traveling thru tach) is correct. It ended up being that way on my 70 Javelin. I had to determine that this was supposed to be the case, as everything was disconnected when I got the car, and I had to do a fair bit of research to get the details. As I recall, the wiring diagram in the 70 TSM didn't show tach wiring on the main wiring diagram, which didn't help any... In any case, I think it's correct, not mickey-moused, and I think the stock tach should be hooked up the same way. <speculation mode=on> I would guess, you could hook *both* tachs up in series (both part of the same "big loop") without problems, but can't say I know that for sure.<speculation mode=off> Nice find on that car... have fun! cheers, Derek Whiteside On Sat, 2 Oct 2004 16:07:49 -0400, John W Rosa <johnrosa@xxxxxxxxxxxxxx> wrote: > > I spent some time today wiping the car off to remove > Thursday's rain spots, using a real high-end chamois > my mommy-in-law got me. Amazing how much easier a > job is with the right equipment! > > When done, I had a bit of time left before having to > leave, so I insanely attempted a 'simple parts swap', > figuring *my* Hornet couldn't be just like Doc's! > > I grabbed some basic tools and the dash bezel/gauge > set I got on eBay (from a 77 AMX) and decided I'd do > the swap. > > The glove box side went nice and easy. The gauge side > seemed to go well, too. I yanked the original set, > took it's switches and gauge cluster off, then pulled > the switches and cluster off the new setup. I then > installed my original cluster onto the new bezel (which > had an original V8 tach on it), then installed my > original switches (I knew they worked and my wipers > have the intermittent feature, which I wouldn't want to > lose). > > I was about to slip the whole thing back into the dash > when I figured I should check all the operations. Well, > switches worked fine, so I figured I'd start the car > and check idiot lights, then gauges. OK- idiots lights > are fine...but the car then cranks without trying to > spark up. That's when I realize the add-on tach that WAS > in there was removed with a quick 'snip' of the wires. > But that shouldn't disable the ignition! A quick call > to a buddy had me looking under the hood to find the > positive lead from the ignition solenoid was cut and > redirected to the gauges, then back to the coil on the > positive side! So my 'snip' effectively broke the long, > silly loop. > > So I yanked the added wires, re-connected the original > wiring as intended and she fired back up on the first > try again. > > I then finished screwing the assembly into place and > put that car away for the night. Note I didn't try to > connect the factory tach. I didn't have my TSM with me > nor extra wire. I simply used what I had to extend it's > wires out the bottom of the dash so I can connect it up > later. Hell, I don't even know if it works, so better > to wait 'til I have more time to tweak and troubleshoot. > > The 'engine-turned' bezels of the 77 AMX sure spruce up > the car's dash. It looked so 'blah' in "tan-with-tan- > over-tan-with-tan-trim". > > Tomorrow they PROMISE me some sun, so new photos then. > > > John > >