Does it have a factory Tach? The juice from the ignition runs thru the tach and a pink resistor wire to the coil. Without the proper resistance you can fry the tach. Just a thought...

 

I hate electrical work. Thanx for the suggestions guys. First off I honestly don't know that the msd box caused this, just a guess because I don't drive car frequently enuf and it occured recently after.Secondly I mixed the two brands for no particular reason other than thats what I came availabe, would not recomend it, the schematics didn't jive with each other. Has anyone seen the price on an underdash wiring loom for '69 -'70, yeesh Oh and Gun Jam,?"the ignition is where you stick the key" dang you musta went to Wyotech or something. Give the newbie a hard time brother. Thanks for the sugestions tho.