I know they are expensive, but a full engine monitor is the way to go. JPI, EI, and Garmin EIS are good solutions. I own a CGR-30P.
A unique benefit of the Garmin EIS is the unit fits a standard hole where the tach is located and most importantly can display fuel levels facilitating 100% elimination of all legacy engine fuel gauges for 100 series Cessna’s.
Believe it or not, a good full featured engine monitor will pay for itself in avoiding engine repairs and provide early indication of cylinder issues for early remediation.