Wiring

[racer48j]

Gramps05,
Do you happen to know the best place to connect the tach input when you are running the stock black box ignition?  I have a ProForm 5" Model #67004C tachometer in my car and it has always shown approximately 1/2 the actual RPM.  Jumpers on the tach have been cut to set the tach to work properly with a 4 cyl. engine.  I have tried all sorts of combinations with the jumpers, etc., but no luck.  The input (green wire) has always been hooked to one of the coil wires.  I don't believe you would want this green wire connected to the common wire that connects to both coils would you?  This has always been a frustration for me.  Any insight would be appreciated.

[gramps05]

Racer48J, is your stock ignition the single black box or the two box system one having a vacuum line going to it? The common wire that goes to both coils is 12 volts dc so do not hook tach input signal to it.

[RickyBobby]

I will take a look at mine tonight.  I run the stock black box as well.

[racer48j]

Hi guys,
My car has the two black box system with the vacuum connection.  And we are currently running with the vacuum line connected.  I was pretty sure that I needed to steer clear of that coil common wire.

[gramps05]

 If you have the 600 wiring harness, on the large box find the large 6 pin connector, there should be a double black wire coming out the back of the plug, one wire to the gray coil wire the other is your tach input. If not splice the tach wire into the wire going to the gray coil wire.

[racer48j]

Sorry it took me so long to get back to you.  We were off racing the car  .  I don't have the extra black wire but I will try splicing the tach input wire to the gray wire going to the coil.  I will let you know if that corrects the problem.  Right now though I have to replace our upper oil cooler, remote oil filter, oil cooler fan, grill, one fender and possibly a couple of oil lines.  We got caught up in a wreck caused by one young drivers impatience.  He had already spun one car out of the way and I guess he decided that tactic was much easier than actually passing them.  The result was four cars eliminated from the main event.    Oh well, I've been around the racin' game long enough to know that kind of driving will get you noticed, just not in a good way.    Thanks again for the info.