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Topic: Help with 4cyl to 8cyl Tach Mod (Read 776 times) previous topic - next topic

Help with 4cyl to 8cyl Tach Mod

Hey guys. I got a new 85TC with 5.0 conversion. The tach is way off and I read the tech info on CoolCats. I have an extra tach from an 88TC to make the resistor mod to. However, the circuit board on my tach and the one in the tech info area on CoolCats doesn't match.

I attached a picture of the circuit board on my tach. Can anyone tell me which resistor I need to replace?

Thanks,
Jon
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Help with 4cyl to 8cyl Tach Mod

Reply #1
Jon,

Though it may have come from a later model cluster, it may be the early tach assembly.  I have completed the update on my tach, it looked like the picture on Eric's site.  I pulled apart an earlier model to compare; they weren't similar in any way. 

I don't have one here with me to compare to your pic.  I check at home later this evening to confirm.

Help with 4cyl to 8cyl Tach Mod

Reply #2
Ahhh, thanks. I bet that is the issue. I bought the 85 with a bunch of spare parts. My spare tach may not be from an 88, that's just what I assumed since the previous owner had an 88 parts car for the 85. Never know, maybe the 88 tach is already installed in the car without the V8 mod. I'll pull that one to compare. I appreciate you checking yours though, let me know.

Jon
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Help with 4cyl to 8cyl Tach Mod

Reply #3
It's confirmed.  You have the 85/86 unit.  An easy way to tell is by looking at the face.  The 85/86 models go all the way to 7k.  The 87/88's go to 6.5k and have the ride control light.

 

Help with 4cyl to 8cyl Tach Mod

Reply #4
Thanks. I guess I gotta sack up and go to the junkyard. Been a while, but we usually have a few 87/88's in the local yard.
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