MSD Digital and VDO Tach

KenC · #1 (**permalink**) 03-29-2010, 05:50 AM

I'm running a MSD Digital 6 with a VDO tach and have yet to get it to work properly. Have tried with and without tach adapter. Anyone else experience this?

zrayr · #2 (**permalink**) 03-29-2010, 07:13 AM

how many wires does the tach have ? Is it voltage or current triggered ?

even not knowing those particulars, I would say it is likely that you need the msd tach adaptor # 8920

http://www.summitracing.com/parts/MSD-8920/

Z. Ray

KenC · #3 (**permalink**) 03-29-2010, 09:52 AM

Running MSD 6 Digital 6520 with 8520 tach adapter. New catalog says no adapter required. Adapter makes it work kinda correct, but can not calibrate using accurately using dip settings on back of tach. Tried new tach and same problem. Most run MSD 6AL vice 8 Digital so I didn't know if that was the problem.

zrayr · #4 (**permalink**) 03-29-2010, 11:03 AM

I am using the digital 6 also, (with the msd 8920 tach adaptor). But my tach is the Shelby factory Cobra tach, which is wired up the same as the '66 Ford Mustang tach. It is a current driven tach. Voltage driven tachs wire up differently.
Z.

KenC · #5 (**permalink**) 03-30-2010, 05:24 AM

Its a voltage driven tach as far as I can tell. One set of MSD documentation says er to use 8920 and newer says use nothing. MSD not a lot of help, nor is VDO. Possibly I have fixed orginal problem and now just need to calibrate tach with another source.

zrayr · #6 (**permalink**) 03-30-2010, 06:55 AM

the 8920 is fairly inexpensive. If I were in your shoes, I'd just buy one, if it fixes the issue then great, if not sell it to someone who really needs it.

Z.

KenC · #7 (**permalink**) 04-05-2010, 09:27 AM

Have tried with and without 8920. I think it may be time to throw the VDO tach in the trash and replace with Auto Meter ??