[Fullback66]

I think I am going to take the points out of my 66 GTO and run with Pertronix 2 or 3.

I was watching a video on this subject, and they said you can not run your stock Tach with the system.

Is this true?

Is anyone running Pertronix 2 or 3 with their 66 Stock Tach?
Did you have Tach problems?

Thanks Guys.
FB66

[Peter Serio]

If you have original GM rally gauges in your car that has a one wire plug in tab on the back of your dash tachometer; that circuit board is designed to work off of the original Points distributor only. The way it works (electrically) is not compatible with any modern transistorized or fully electronic ignition conversion.

[Fullback66]

Thanks for the information Peter.

THAT BLOWS! I will stick with points.

FB66

[Jeff Hamlin]

I've been running the basic Ignitor set up since 2000 on my factory Tach with no issues.
I don't recall any mods, is there something different with the newer set ups?

[Fullback66]

It has a rev-limiter in 2-3. This is the web site where I got the information.
If you are running on Basic. I will give it a try.

https://www.youtube.com/watch?v=uQ0smsIO8Js

Thanks
FB66

[Peter Serio]

Just a warning; newer versions of these electronic ignition conversions are easily capable of damaging a one wire GM car 1960s & early 1970s tachometer.

Especially ones with a 40,000 volt output coil and/or a programmable rev-limiter. The stock tach was never designed to de-code these type of signals. The original GTO rally gauge factory tach is a very simple design just smart enough to read the opening and closing of a set of contact points.

Many of the new high energy aftermarket coils have a less ohms resistance on the primary winding than the original GM coil that ran with a points distributor. Fewer ohms resistance on the primary yields an intense "kick" to the "-" terminal when the field collapses and this type of a signal cannot be read by something designed in the mid 1960s.

Some of the the brand new Mallory cast aluminum "all in one" distributors come with a built-in low amperage dwell signal wire that runs out of the base of the distributor. This wire is specifically for a tachometer, they tell you in the instructions for this set-up NEVER EVER wire a tach to the "-" side of this coil. Same with the MSD 6AL. They give you a specific wire that exits out of the red box module for a tach. This is a low amperage 12 volt pulsed signal designed to protect your tach. It still wiil not work with a one wire stock tachometer. You need the kind of circuit inside of the tachometer that has 2 wires; plus ground.

One wire goes over to the fuse block (thru a one or 1 & 1/2 amp in-line glass fuse holder) and gets 12 volts of "+" power with the key on. the other wire runs out under the hood and looks for a pulsed signal whenever a spark plug fires.

[455hota]

In my 1966, I am running a Dave’s Small Body HEI conversion distributor. It has the GM HEI module mounted on the underside the the distributor, and retains the stock looking distributor cap.
Anyway my original rally gauge tach has worked with this set up for years now. But I have recently learned that my 66 was equipped with factory Transistorized Ignition. And the tach that came with TI has two connectors, not one.
Is this TI tach the reason it works with my HEI conversation distributor?


Sent from my iPhone using Tapatalk

[455hota]

https://www.davessmallbodyheis.com/

Here is the link to Dave’s Small Body HEI conversions.


Sent from my iPhone using Tapatalk

[Peter Serio]

Absolutely!! The GTO series cars: (1964, Tach only and/or '65 & 66) rally gauges (when the car was ordered with optional TI ignition) is 100% compatible with a 1970s GM HEI ignition set-up. A 2 wire T.I. tachometer will also work on any of the modern aftermarket conversion modules such as Pertronix, Accel or Mallory.

Originally Posted by 455hota

In my 1966, I am running a Dave’s Small Body HEI conversion distributor. It has the GM HEI module mounted on the underside the the distributor, and retains the stock looking distributor cap.
Anyway my original rally gauge tach has worked with this set up for years now. But I have recently learned that my 66 was equipped with factory Transistorized Ignition. And the tach that came with TI has two connectors, not one.
Is this TI tach the reason it works with my HEI conversation distributor?


Sent from my iPhone using Tapatalk

[Fullback66]

I need to find my Pontiac Historical Society papers.
Where did I put them???
I know they are around here somewhere.
FB66

[tallrandyb]

Originally Posted by Peter Serio

Absolutely!! The GTO series cars: (1964, Tach only and/or '65 & 66) rally gauges (when the car was ordered with optional TI ignition) is 100% compatible with a 1970s GM HEI ignition set-up. A 2 wire T.I. tachometer will also work on any of the modern aftermarket conversion modules such as Pertronix, Accel or Mallory.

Reviving this conversation, I'll check my tach when pulling dash next summer. I'm currently running a Pertronix Ignitor 1 ignition and the Rally tach has been working fine for over a year since I got it; a little lazy sometimes on startup then will kick up and runs fine.

So maybe the installed Rally Guages has a two-pin tachometer installed already? If not, is there a modification in the circuit I should look for? I'll try ducking under the dash to get a look at it, likely remove ashtray to get a better shot. I have a Pertronix Ignitor 3 I'm planning to install for multi-spark and soft rev limiter.

Also Pete, do you have rally tach faceplates with the 5100 redline for sale? My 65 was built late June/early July 65 and currently has full-green tach.

Thanks!