Don't know if anyone would be interested. But I tested out installing a cl***ic stewart warner 970 series pedestal tach (that includes the 977 in dash also) on a gm hei ignition system. The sw 990b ignition monitor was used and it made the tach work without burning up either part. Just fyi, it was only for 5 minutes. This weekend ill try it again but for at least half an hour. Also tested out was the use of a tach filter between the ignition coil negative to the 990b monitor to the tach. This made the tach not function at all. Just seen that question asked a few time on different threads and forums.
Good info. Often wondered if I could use my 970 on a HEI. Unfortunately, sold it and went with a Model 465 tach for my Model A. Please do the follow up. Canuck
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