Gaffrig Tach,s go wild over 4000 rpm's jump past 6000 rpms.at times I seem to remember something about this with 500 efi,s. and it was not the gauges. Before I rip out the dash.

Many years ago.......so I could be fuzzy, I remember a ground being the cause of an express cruiser. Yes, it effected both enginees.

Thats what I was thinking.