I've also got an ancient Sears Penske dwell tach. It only has an 8 cylinder and 6 cylinder scale with a note on the meter face saying to double the 8 cylinder readings for a 4 cylinder.I have a vintage sears penske meter. Has a setting for 4 cyl. I can't swear that its working properly. I'll turn the setting to 8 cyl and see what it reads.
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