I am hooking up an MSD 6AL to a stock DJet distributor. Which tach adapter? Anyone know the diagram pages for the installation manual that apply? Yes, I have done a search

Here 'ya go......With my orignal six I used the 8910 tach adaptor....With my 3.0 with factory electronic pickup I'm using the 8920 tach adaptor. You should be a able to use the 8910.....Hope this helps, if not, I'll put up some more info.

Click to view attachment

I never got that adapter to work with the stock /4 tach. I tried 3 different adapters, none of which produced a signal the /4 tach liked ...

Andy

I had to run a tach wire from the adaptor to the tach on my 2.0 six (using a Crain Optical) to the tach. For some reason the factory wire didn't work....

Thanks guys! Got it.

According to MSD the VDO tach when using the white trigger wire should use the #8910 adaptor, and when using the magnetic trigger connector uses the 8920 adaptor....

I bought this from Andy and got it to finally work...

Here's a link to My Webpage showing how I was able to hook it up.

-- Rob

I tried a 8920 but that didn't work for me either. Oh well, i'm glad you figured it all out!
Andy

It sounds like some tachs don't even need an adaptor to work with some of the CDI ignitions (like the MSD is). It may be something to do with early vs. late tachs, but I haven't been able to trace a real pattern in the Pelican board posts.

--DD

I think it does have something to do with the vintage/source of the tach. I recently had to install the 8920 adapter for my 70/71 911E tach and magnetic triggered dizzy. Without the adapter, the tach did not see anything that registered a reading at all.

Note that I've heard the speedo shops (NH or PA) can modify the tach to essentially have an internal adapter, but I had already bought the adapter when I learned that.

Gratuitous pic -

Rob and I went the simple route (I subscribe to the KISS method when possible) and hooked the tach wire to the "Tach Output" on the back of the MSD box.

I will admit I cheated and read the instructions for the MSD where is says:
"The MSD Ignition features a Tach Output Terminal on the side of the unit. This terminal provides a trigger signal for tachometers, a shift light or other add-on rpm activated devices. The Tach Output Terminal produces a 12 volt square wave signal with a 20% duty cycle."

Jim

Yup! Anyone need a $50 tach adapter? 8910? Frustrating as all get out. First I hooked it up and it worked but no tach. Then I went to the speed shop and got an 8910 and hooked it in. No difference. Car was running noticeably smoother and had better throttle response but no tach. Added the diode they supply but now it will not run at all. Then along comes Jim and reads the instructions.