I have a 1958 Tach drive generator off of a corvette and a early 60’s 8k RPM SW mechanical Tach and I was wondering how to figure out what ratio reducer or multiplier I would need to make these talk to each other correctly. Thanks for any info, Joe
The first thing you'll need to do is figure out the drive ratio between the crank pulley and the generator. Most generators are driven at well over 200% of the actual crank RPM, just how much over you'll have to figure by checking the crank/generator pulley cir***ference. The SW tach was probably designed to be driven off a tach-drive distributor. You'll have to find out what ratio that uses, then go from there. If all else fails, a speedometer shop could test it and tell you how many input RPM equals indicated RPM.
The Jalopy Journal
