does it matter wat +12v for the 12v igntion wire i use and signal to -ve on onea the coils? where abouts is the oil temp sender? cheers

 

Why would you want to install an aftermarket tach when you have a big *** tach in the center of your gauge cluster?

 

this one has 3 other smaller guages, it was a late christmas present, plus the stock tacho stops at 8000 revs, does it go to the pos on the two coils or -ve, instructions say -ve and just wanna make sure.

 

thats cool, but run your motor past 8 grand and see how long it lasts

 

nah for future drag engine, anyways do u know how?

 

lol, no sorry, ive never had a desire for aftermarket tachs, just use the instructions as if it were a 4 banger, thats all i know...

 

hmm k thanks. the instructions are **** house though.

 

Because the stock tach on a 79-85 RX7 is guaranteed to be at least 500rpm off anywhere over 6000rpm. Mine was also off at the low end, but in the opposite direction. Read low on the low end, read high at the high end.

 

It doesn't matter which coil you attach to, they'll both read the same.

Pick any switched 12 volt source to power the tach. If you want the tach's lights to only come on when you turn your lights on, you'll need to tap into that circuit also.

The stock 1st gen doesn't have an oil temp sender so you have to find a place to install the sender that comes with the gauge. I went into the oil pan right next to the oil level sensor. This seems to work OK. Just look at it and you see what I'm talking about. You can also buy an adapter that lets you install an aftermarket oil temp and oil pressure sender. Try Racing Beat or Mazdatrix.

 

Damn, Gregs, are you having a bad day??
Some of us don't have stock engines

but to answer the question...
each coil pretty much gets a heavy black wire, and a yellow/striped wire? (stripe color is dependand on year... but typically yellow/green)

You need to connect to the yellow-green.

if you look at your coils, each will have a male spade terminal part coming off of the post where the yellow/green wire clips on, use the bottom unused terminal for your tach signal wire. I usually use the trailing coil (rear most coil)

 

i just connected my wire to the spade terminal it self. also i used some sensor next to my oil pressure sensor as my oil temp, but im getting pretty high readings from both oil pressure and oil temp, im using the senders there, cause i havent had the time to take them out and use the ones that came with the tacho. Regarding acurracy, it was 500revs less then got more and more less and i reved harder, but now its iabout 5% less then the stock tacho at certain revs. its not bad for 155 +15 postage thats aus money. now my speedo died, i may have bumped something.