1964 Full Size Tach with converted tranzister ignition

[1964gp]

I bought an original tach for my 1964 GP. My car has been changed to tranzisterized ignition. Will this original tach work on my car or is there something else that needs to be done?

[Larry]

I did a quick Google search and see a lot of questions like yours.

There was a particular post (from where I do not know) by Padgett Peterson of Orlando. There he describes what is involved in converting tachs to different uses. He makes it sound easy... but then again Padgett could probably build a space ship in his garage and make it look easy-- one very smart guy!

Let's see if someone has a magic bullet for this problem, but in the meantime do a search on "tachometer transistor ignition convertion" and start reading. Most all responses I saw were "no problem" but be very sure before trying.

BTW, is your transistorized ignition "factory" as they were offered then, or aftermarket?

If you check the article in our On-Line Magazine at http://www.pontiacregistry.com/members/online_magazine.php?view=1&article=769 about 1962-64 tachometers, you will see that there were non- and transistorized head assemblies available.

[1964gp]

Hi Larry Thanks for your reply. My car was converted to tranzistorized ignition about 4 years ago.
Tony
PS My car was the Calendar Car in 11-09.

[1964gp]

Thank you. Very helpful.

[Larry]

Hi Tony,

I remember. Great car!

I am in contact with tachometer (and all-around Pontiac expert) Padgett Peterson to try and get you some direction here. I'll report back as soom as I have ananswer for you.

Larry

[Larry]

Padgett has come back with a question:

Well the first question is which tack does he have. The passive tach has a one wire connection to the coil. The transistor one designed to work with the Delcotronic ignition also has a wire to a 12v source.

Please give us as much information as you can. Perhaps part numbers, description, wire colors, etc. Do you have the installation instructions?

We can certainly fix this for you AND save the information for people who run into it again later.

Check the diagrams and parts list in this article to see if it helps you identify what you have:
http://www.pontiacregistry.com/members/online_magazine.php?view=1&article=769

[1964gp]

Hi Larry.
Thank you for all your work.
My tachometer has three wires.
White Has terminal for bolt. Ground
Blue Has terminal for fuse box & is connected to the bulb
Brown This wire has been lenghtened & has a slip on type terminal that would go a blade connector

The tach has a 1964 face & knob but no numbers on it.
The dash mount bracket has the 1964 # on it. I am assuming that it is a 1964 tach

[Larry]

This is getting corn-fusing!

I sent your description to Padgett and he replied back:

Forgot about the bulb. Not sure about white - is there one or two terminals with red insulators?

He also sent: BTW I put the instructions on the web some time ago:
http://padgett.performanceresearch.us/cars/ttach.htm

However, I think you would have to really be into electronics to understand what the schematic is "saying."

We'll keep on it!

[1964gp]

Hello Again
Let me try to clarify what I have.
My Pontiac is a 1964 GP. About 4 years ago it was converted to after market electronic ignition. It has a regular coil mounted on the fire wall & the electronics that replace the points hidden in the distrubitor head. It all looks like stock.
The tach I acquired has thee wires.
One wire is white & is definetly the ground because it attaches directly to the tach head case.
The second wire is blue & attaches to the light bulb socket on the tach & the dash lights on the car. I connected the white wire to negative 12V power source & the blue wire to the positive. The blub illuminated.
There is one wire left. It is a very dark red (almost Brown) color. I feel that this must be attached to the coil.
If the tach is in working condition, will it operate as it should with this set up?

Thanks Tony

[Larry]

We're almost there!

One last review of everything by Padgett (tonight, hopefuylly) and we'll post the information you need.

My question now though is do you have a transistorized ignition or just an HEI?

Don't go hooking it up quite yet. Unless you just want something pretty to set on your desk.

[1964gp]

Hi
Sorry if I caused confusion. I do not have tranzisterorized ignition. I have electronic ignition. I thought that they were the same but have now learned that there is a difference.
I very much appreciate all the work you have put into this.

I had a photo book made of the article about my car & display it with the car at all the shows.

Thanks,
Tony

[Larry]

Hi Tony,

I suspected there might not be a full-blown transistorized system happening. I think you have an HEI conversion. CORRECTION: meant to say Pertronix or similar electronic conversion; but the information below also applies to HEI.

Regardless, your "passive" (ponts system) tachometer will not work on this ignition system without conversion... and we finally have all the information to post.

See our On-Line magazine article on this subject at: http://www.pontiacregistry.com/members/online_magazine.php?view=1&article=783
In summary, this is the information you need:

The components illustrated in the schematic below can be purchased and assembled in a small box and simply wired in series with your tachometer hookup. As shown, two wires will connect to your battery and coil, and the other “To Tachometer” lead connects to the tach wire that normally would go directly to the coil (another can be a ground wire– read explanation above). The other “stock” tach wires should be the ground and the lead that goes to the battery for the lamp.

This circuitry will allow a passive (non-transistorized ignition) tachometer to be used with a transistorized ignition system such as Delcotronic (or similar) or an electronic ignition system such as a Pertronix (or similar stock or conversion).

For use with an HEI ignition system, it is recommended to replace the R3 (3.3k) resistor with a 1.8k resistor.

Note the 1-amp fuse installed inline with the coil lead. This is recommended as it will protect the ignition system if the tachometer circuits shorts, allowing the car to still start.

I hope this helps.

[1964gp]

Hi
Thank you very much to both of you for all your help & information. I will continue to tell people of the advantages of belonging to our club.

Now I am off to the electronics store to get the parts.

Thanks again,
Tony

[Larry]

OOPS!

I said I thought you might have an HEI, I mean a Pertronix or similar conversion system (which is an electronic ignition).

I forgot about your mention of a coil. I assume you mean an external coil (which the HEI has on the distributor).

The conversion Padget has designed will work with either the Delcotronic transistorized or Pertronix or similar electronic conversions. And, with a small modification, will work with the HEI too.

Keep us posted.

[1964gp]

Hello

The coil on my car is attached to the fire wall where the original coil was attached. My mechanic tells me that it is the same as the original coil, only slightly more powerful and FIRES FROM THE NEGATIVE SIDE of the coil. Will this change the instructions and will the tach function with out the amplifying circut?
Thanks,
Tony