Tachometer
 

81 911sc, tachometer jumps all the way up and comes back down on initial start up, stays pinned at the bottom after, any thoughts?

Check battery voltage when running at multiple rpm bands.
Often the tach acting like that is a sign the VR is failing.

Not to highjack this thread, but my Tach needle "blips" at engine start and shutoff, but pinned at zero all the time when running. Worked fine before a battery replacement. Perhaps also the VR?

MSD ignition?

Todd

Yes

The older MSD ignitions sent a "redline" signal to the tach when first turning the key on. You can disable this with a kludgy "short circuit" step, or just ignore it. I'm assuming it works otherwise (the tach that is)?

The newer MSD boxes have this disabled by default and you do the kludgy step to enable it.

Todd

Warren did you check the VR as suggested by timmy2?

Today, no my Tach is dead. Wondering if it is voltage related