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I have a new to me 1980 that the tach was not working when I got it.
I replaced the tach circuit board, put 12V to it out of the car, removed the needle and reset it to zero.
I put it back together and started the car, the tach shot up to 3500 ish even though it was idling at around 1000. When I rev it to what should be around 2500 it swings way over and pegs out into redline. I tried redoing the zero procedure a couple times but still have about the same results.
I still need to take a look at the filter but anyone have any other ideas? Maybe my new board is bad?
Had a similar issue. For me, turns out the gauge itself was bad. It has 2 windings and one side was open.
Measure for continuity between the posts for the gauge itself, not the power connectors.
I will take it back apart this week and check for continuity.
I was looking around online and only see tachs for a 1980 with the 305, I have the 350.
Any idea where I can get a tach?
Thanks.
I skimmed the first few posts in that thread and it seems you were working out a few things. Then I read your post #140 with the link to the EBay seller with the new board. If I understand correctly you went through about 4 boards and that was your issue all along with the tach?
I have a feeling I have a bad "new" board, I can accept having to buy another one but after that I don't care to waste more money than I already have.
Tach Reading High After Replacing Board
