Don Terrill’s Speed-Talk

Heres a dumb question and I am trying to figure how to word it. What is the rpm diference between 6 cyl setting and 8 cyl setting if the eng is an 8 cyl but the tac is set on 6 cyl.

A little more explination as best as i can. if an 8 cyl is turning 6000 rpm but the tac is set on 6 cyl scale what would the tac be showing as rpm.

-The math says it's a 1.3333333 difference (8 divided by 6 = 1.3333333) which means that you are sending 1.33333333 more pulses to the tach than you should be.
-so 6000 times 1.3333333 = 8000rpm.
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-I just happen to have a tachometer on my ignition machine that has the 4-6 & 8 switch so I tested an 8 cylinder at 6000 rpm and the tachometer when set on 6 cylinder does indeed read close enough to 8000 to believe the math (if you use all seven 3's).

thanks, bill.
that saves my insanity LOL