Any idea what causes voltage spikes, tach jumps irratically on my 79 rx7

 

Bad distributor. Either replace the base plate that the points ride on, or convert to an FB electronic ignition.

Rich

 

DAMN! my 83 does the same. WTF?

 

I had to change the coils on mine.

mine would start jumping. and then the tach would go dead. but yes, I changed the distrubitor and coils too.

 

My tach started jumping around for the first time just a few days ago. I tracked it down to the ignitor plug (not plugged in all the way). I had had the distributor cap off to check the condition, and I guess I loosened the plug a bit when I did that. Plugged it in all the way and all was fine once again... On a points type ignition, I've no idea what would cause that.