An alternative to a $200 tachometer might (just MIGHT, as I haven't tried it) is the tachometers they sell for use with model airplanes. Tower hobbies www.towerhobbies.com has them. They work by seeing the prop blades go by, which causes light flicker. Of course, be careful when standing anywhere near a running airplane engine.
Also, automotive tools often include digital tachs which work off a single plug lead, and count sparks then convert them based on number of cylinders. They're accurate. And cheap. Greg
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