Just recently installed my MSD 6AL. It running fine and the tach works well at idle and cruise..When I went WOT the tach acted all screwy and was floating and even moving down as the car was making higher RPMs, any ideas what would cause this? thanks

 

just went over the wiring diagram again. I checked continuity between all spices,all good. The only thing I wired different from the diagram was the main negative off the MSD. In the diagram it was shown to land under the battery negative terminal but being the wire was short I just landed under a bolt on the fender, could this cause my issue?

 

ok, after reading a lot of old posts I have learned I need a "Tach Filter". I've seen a few part numbers 8910 and 8920. I just ordered the 8910, just wanted make sure thats the correct part number for my car? thanks

 

bump

 

MSD 8910 was the fix

 

Do you have the factory tach or an Autometer/aftermarket tach?

I am wiring my 6AL now and have a few questions if you dont mind....

I am using a autometer tach and have a stand along harness for the LT1 which has a lead to hook up to the tach. Any idea how i should wire up to the tach because now i have the 6AL that has an output for the tach as well as the wiring harness.

Also, so it worked ok to ground anywhere instead of the battery ground? I relocated the battery so its going to be too long of a ground to get to the same as the battery. I was just going to ground to metal chassis inside the passenger compartment where i have the MSD mounted.

THanks.