What year tach to work with MSD?
 

Before I buy another tach does anyone know what is the first year tachs are able to work with the MSD. The one in my '69 does not. I searched but never found a definitive answer. Thanks, Sam

I have absolutely no idea, but I would think none would work because MSD is multiple sparks per time, and conventional tachs would be calibrated to a single spark depending on the ignition type.
Does the company website show a compatible one?

An electronic tach works(I think something like this) because when the coil is being charged up, it sends voltage through the tach wire which creates a magnetic effect and attracts the needle, which is normally resisted by a light spring.
The more the pulses, the farther the needle is pulled.

When I mistakenly installed a Nology coil(that wasen't made for CDI systems), the engine ran like bunk and the tach showed around double the actual RPMs.

I just wanted to have four posts in a row.

MSD and Tach....
 

I have the MSD-6A box in my 1980 911 SC coupe. The tach works just fine without any adapters or accessories. When I installed the MSD box, I simply ran the supplied black wire from the tach connection on the MSD box to the appropriate connector on the master plug that previously connected to the Bosch CDI. Anyway, to answer your question, I KNOW that a 1980 tach will work ok.

By the way, the car runs really well with the MSD unit installed. The Bosch CDI in my car had some major problems so I don't know if the MSD is actually better than a good Bosch unit. However, it provides very good ignition performance and cost about 1/2 of what a rebuilt Bosch CDI would have cost.

Good Luck!

Fred Cook
'80 911SC coupe

As far as I understand the internals changed in the tachs themselves around 197?, thats why the early tachs pickup off of the coil, and the later ones pickup off of the Bosch. I think its a voltage thing. Anyways, my tach reads double or triple the rpms below 3000rpms. And perfectly fine above 3000rpms when connected to the coil. When connected to the MSD tach output it doesn't read at all, when connected to the points pickup wire and an mSd tach adapter it works erraticaly at best.

Can anyone narrow down the year possibilities. Sam

Noah, I searched but did not find anything about Cam B's setup do you have the link?

Sam;
Do a search for for posts by me on MSD's and I've posted a schematic and details about how I wired up the MSD in my '69E.

It works perfectly with no compromises.

Here it is, follow this link.

I had to use one from a 73....
The 69 WON'T work, even with an adaptor (and is for sale!)

I put a MSD in my 74 911 and could not get the tac to work with any adapter or any way I wired it, so I bought a autometer monster tac and installed it. fit great and worked better than the stock one

I use one on my '66 911 (green numbers) with the MSD Tach addapter, No problems Using pertronix Ignitor as a magnetic trigger and a MSD Blaster 3 coil. Seems to me I had to use the MSD coil for some reason I cant remember

I have a '76 tach, part number 911 641 301 29, with MSD and NO tach adapter. Engine is '83 3.0. The tach sticks occasionally around 3000 rpm, but I don't think that has anything to do with the MSD. If you need a new one the 78-83 tach is a lot cheaper and should work fine.

Does the Autometer tach incorporate the turnsignals and highbeams?

I've had this EXACT problem when I installed the MSD in my 71 with 2.2S motor. I wired it 100 different ways, and at best I get double the real RPM below 3K and accurate when at or above 5K RPM. I remember someone (red beard?) posting that their only recourse to this problem was to send there tach to Hollywood Spedo to have a new electronic board installed. Well I work near Palo Alto Spedo in the bay area so I sent them an email, sure enough, they are very familiar with this issue and have a fix...hold onto your hats... they want $185 to fix the problem.:eek:

So, I would rather go to Parts Heaven or Easy and pick up an SC tach for $100 or so, but don't know what year is the right choice, anyone know?

TIA,

Thank you everyone for your opinions and ideas. No matter what I've tried no dice with the wiring. So I guess I'll play it safe and go for the 78-83 tach. Does anyone have a picture of one so I can compare it to mine. Thanks, Sam