The barrel tach in my 68 Chevelle is reading about 20% too high. The dash is an original SS type. The engine is not stock, it has an MSD distributor and 6AL ignition box. I don't even know where to start to check it out.
Suggestions please.
Thanks,
Greg

A little off topic, but how did you get the tach to even read with the MSD setup, we have one as well but when the MSD was hooked up, it fried it and needed rebuilt.

Thanks
Jason

ditto jason... mine registered for about 1/4 second.

Well I know from the two posts that wiring of the tach is delicate or difficult. Does there need to be some type of conditioning unit between the MSD and the tach?
Since these two failed, I am reluctant to do much to mine.

'68 roller tachs are known for incorrect readings, and they're really too small and too deep in the dash to see the needle very well. If you want a more accurate tach, I'd go with an aftermarket that you can clamp onto the steering column. JMO
BillL