Problems With 911 Tach and MSD
 

I instaled a 911 Tach in my VW Kombi Bus 911 2L S and MSD-5 ,& the tach
have a malfunction when is conected.
The problem disapear when don't use the MSD.
In the past i used a normal VDO tach with a same MSD-5 without problems.
Somebody have a idea wich is the problem?
This engine use a stock distributor with point & condenser and the MSD-5
is to use with point.
Maybe a Porshe 911 tach is not to use with a MSD?

Regards.
Mario

Many factory tachs don't work with MSD ingnitions. My VDO tach in my BMW won't work off the ignition box but works if I take the pulse off the + terminal on the coil. Try that and see if it works. MSD makes two types of signal adapters to make their tach signal work on factory tachs-they sell for about $30 or so. Call them if you want to use the adapter so you can be sure you get the model that will work with your tach.

ken

Problems With 911 Tach and MSD
 

Thanks Ken,i will tray with a + in the coil.

Regards.
Mario

I think the Neg. terminal is the point you want to take the pulse from. The + terminal will just put 12vdc on the sense line to the tach and could damage it.

Problems with 911 Tach and MSD
 

Yes is a risk,i contacted MSD technical suport and them recomend use
a Tach controler PN8910 to control the -pulse to the tach.

Thanks.