NOS tach problems

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db's demon

db's demon

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I purchased an NOS tach from another fabo member, and I am having a problem with it. It is a Dixco column mount, 10,000 rpm. It was the one I really wanted. Here is the problem - it seems to be quite accurate at an idle, but as you rev it up, it goes much higher than it is suppose too. Idle at 950 is OK - 2500 on another tach or timing light shows 3000 on the Dixco tach. I had all three hooked up at one time and could compare them. Other than being internal - any suggestions? Thanks Darryl
 
I don't know the answer, but I'm wondering why the 4sale thread you bought it from was "closed" :silent:
 
Do you have an MSD ignition? I had a working vintage SUN tach, the tach would read at idle but the higher it revved up the less accurate it was, worked fine before I installed the MSD.
 
Hi Darryl, if its from the early 70's it will be off, thats why most back then who were serious racers used the mechanical tach's, You should be able to send it out to redline or one of the other dash restorers to replace the internals with modern solid state electronics. BTW hows the choke and idle solenoid working?
 
Any chance it has a number of cylinders setting? 4-6-8 switch under back cover?
 
Ah Yes! Just re-read your post. Dixco made a lot of the hood mounted Tach's back in the day. I remember having to play with a handful of resistors once on an old Sunn in a Mustang. I believe I had to raise the resistor values until I got it to match my Shop Tach. Can you get your hands on some resistors with different values? Possibly radio Shack? Can you post some pictures of the resistors you have and the Tach itself? I think Just maybe if you put another resistor right in-line with the wire to the coil you could fix it. I'm Guessing there's 3 wires, 1 for light, 1 to coil negative & 1 ground. I'm not an expert just thinking out loud. I wonder if the Tach originally came with some extra/spare resistors.
 
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