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Posted by: tbox56 Nov 24 2004, 09:33 PM

I have a "72 1.7 with a tach problem. The tach will show an accurate reading of say 2500rpm and then spike to 4500 or 5000 rpm, with no change in engine speed. Any ideas what the problem is or is the tach shot?
Thanks, Tom

Posted by: redshift Nov 24 2004, 09:44 PM

I have no idea where, but somewhere, there is a schematic... it's near to where we are right now... but...

Sounds like a loose wire somewhere... like maybe the tach wire needs attention, in the engine hole.


M

Posted by: SirAndy Nov 24 2004, 09:45 PM

i had the same problem and on my car it was a faulty relay board.
some of the connections had corroded and were broken or shortening out ...

it's probably a long shot for you, but if you have access to a know to be good relay board you might want to switch them out just to see if that changes anything ...

Andy

Posted by: type47fan Nov 25 2004, 10:39 AM

It was along time ago but. . .I had a similar problem with my '72. Check the mounting base for the points inside the dizzy. My tach would spike and I found the little metal ball/socket component had lost its spring tension allowing sloppy operation of the assembly. Replaced that little metal socket and solved my particular problem. Hope that made some sense.

Posted by: ! Nov 25 2004, 12:44 PM

Also...if you have another tach....hook it up and see if the problem is repeated. But more than likely it is a short somewhere like suggested above....