I am putting in a rally pack tic toc tac, replacing the warning light gauges. I'm a little confused about the tach/clock wiring. My aftermarket tachometer had four wires: ground, 12 volt power, light and coil to tach connection. Now, with the rally pack tach/clock: terminal for clock, terminal for light, terminal for coil to tach and ground, of course is housing to dash metal to metal connection. Shouldn't there be a 12 volt power connection, or am I misunderstanding something?

 

Welcome Nelson! What year is your olds?
I did this conversion over a year ago.
The tach gets its power from the clock power terminal, which is constant 12V. This is the thick orange wire (in 72 at least.)
The gauge cluster has totally differerent witing configuration than the idiot light set. I think there is a good wiring chart at 442.com if you do not have the chassis service manual.
Let us know if you need any other help!

 

Yes I agree with Rob, you power is going to be from the clock and it should be orange. I have found that Olds used that color for quite a while in the seventies, perhaps longer. Welcome to our site.

 

One other thing, Nelson - are these repro units or factory?

If repro, visit my flickr photo site in my signature and see how you ~may~ need to open them up and paint the interior for better night illumination.

 

The factory used a brown wire for the tach feed from the coil right in the main harness if it originally came with a tach...The guages use the same wires but in a different order than idiot lights...it's in the shop manual...you have to unlock the pins in the connector and switch them around...

 

Here you go

 

Thanks for the help and welcome. I would guess the ignition coil to tack shielded cable loop goes to any convenient ground. Right? Thanks again!

 

If you use the correct shielded cable, then the shield part of the cable goes to ground. The inner wire goes from the tach to the disty side of the coil. When I did mine, I cheaped out and used a regular piece of unshielded wire; no issues as of yet...

 

You members have been extremely helpful. I'm confident I can get it done when I pull the car out of hibernation in the spring. By the way, the question was asked as far as what I have. I have a 1970 442 that I've had since 1974. If I had the opportunity of buying it new I would have ordered the gauge package with it, but I was not that fortunate. I'm just happy I could get it 4 years after its assembly date. Thanks again!

 

The conversion process was in Journey With Olds (the Oldsmobile Club of America newsletter) probably 6 or 8 years ago. It really didn't seem that hard.