Farnswj

I compltely gutted the Thunderbolt ignition system, and replaced it with GM marine HEI distributors...engines run fine. I would like to find out any compatibility info. on my existing tachs. Is the operational voltage the same ? A friend said the Thunderbolt ignition operational voltage was 6 volt. l did'even wire up the new dist. tach wires and port is reading some kind of spurious signal that is roughly double the actual rpm. Can the original Stewart Warner tachs be adapted to my gray HEI tach signal wires ? Any info. would be greatly appreciated 😉

boostbros

i dont know of any 6 volt thunderbolts as for the delco est hei i have put over 1000 in various engines even big block fords we mated ford gear and shaft with est top it worked awesome even reverse rotation most of the time the tack will work but i have had a few older ones where the tach did not last long the est,s love 14 volts with a good sized wire instead of locking in down i set top end timing the more advance at idle the better its often 15-21 degrees idling for a non vortec small block with top timing at 30 degrees vortec is 26 on top hi performance stuff max is 34