Re: Tach for 70 AMX

Yes, the tach is wired in series. The tach can malfunction and leave you stranded scratching your head wondering why you have no spark. I've had it happen to me and heard of others. When it happened to me, the car would act like it was losing power and then would not start. There is a built-in ballast resistor in the tach, along with the circuitry to operate the tach itself. If something goes wrong (this stuff is over 30 years old now), it can leave you stuck. I changed the coil, ignition switch and ran a straight 12V wire to the coil to get me back home. After consulting with another AMC buddy who had the same problem, I quickly found the problem. Replacing the tach took care of it. The '70 TSM shows the wiring for the tach. Learning the hard way can be a pain sometimes! Maybe someone who does the rebuilding of these can make them just an add-on and not in series. Good luck . . .

Bill Dettman

'70 Javelin SST BBG 401, '74 Matador X 401

From:  farna@xxxxxxx
Reply-To:  mail-From-javelinman-hotmail.com@xxxxxxxxxxxx
To:  mail@xxxxxxxxxxxx
Subject:  Re: Tach for 70 AMX
Date:  Wed, 23 Nov 2005 08:17:45 -0500
I just printed an article in the last AIM about connecting those tachs. If someone wants to scan that article and send it to Todd go ahead. I think it was in the last issue. Todd, if you don't get something from someone send me an e-mail and I'll get it to you. All late 60s/early 70s tachs are the same, but I forget exactly how they work. They are in series, I think, at least not a simple negative wire sensing hookup like more modern electric tachs.

On November 22, 2005 Tom Jennings wrote:

> This guy's Mopar board looks really nice.
>
> On Nov 21, 2005, at 5:59 PM, Todd Tomason wrote:
>
> > I've been working with an electrical engineer that designs and
> > manufactures
> > replacement circuit boards for tachs.  He's been doing mainly Mopar
> > so far,
> > but is trying to branch out.  I sent him a Tic-Toc-Tach for a 71-74
> > Javelin/AMX to take a look at, and he found out that it uses the
> > same board
> > and clock module as the Mopars.  His website is
> > http://www.realtimeengineering.com/, but he hasn't added the AMC
> > info yet.
> >
> > Someone sent him a tach for a 70 AMX and he's trying to figure out
> > how it's
> > connected to the car.  He said after looking at it that it might
> > connect in
> > series with the coil.  Is anyone familiar with these?  I'd like to
> > get him
> > pointed in the right direction.  A wiring diagram would also be
> > helpful.
> >
> > Thanks,
> >
> > Todd
> >
> >
> >
> >

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