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Curve Crazy GT
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Discussion Starter · #1 ·
Just a quick question my tach seems to me to be a little screwy. when im at idle it hops from about 700 (my idle) to about 1000 rapidly, then settels after a little time. then say i go to 4000 rpm and shift it will bounce from the current rpm and back to 4000 were i shifted from(sometimes further) and back, about 4 or 5 times before it settles. now is this normal, or is it broke? also if i go for a redline shift it stops workin at 5600 and doesnt go any further but i can hear the motor keep goin.(i know its pushin this old baby :D ). i know alot of u older guys, like my dad say, "if u wanna do it right, do it by ear" or mabey thats just him, and me being inexpirenced cant tell to well.

so any one who has had this problem or know what it it please help


thanks
chris
 

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Curve Crazy GT
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399 Posts
Discussion Starter · #3 ·
seems fine. but if i shift like im supose to it dont do it that bad and the tach still reads right. so any thing else?
 

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6,344 Posts
You may want to check the tach input wire on the coil to make sure it is securely fastened to the coil. I had a loose wire there and it made the tach do funny things.
 

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Curve Crazy GT
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399 Posts
Discussion Starter · #5 ·
k ill check that to. but i have a question is all your guys tach like super solid and allways on the mark say when u rev it, or does it bounce back and fourth?

thanks chris
 

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Mine bounced when I first put it all together, I changed to a clearer Tach, and it turned out I had the Tach wires reversed. Duh! :eek: Check the wire Ron suggested and then the wires at the back of the tach. Also check the Tach ground and the Tach/instrument cluster grounds. I've had problems there too. HTH, Jarrell
 

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Member
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I've got a similar problem. It had no bounce and moved steady, then I installed a Pertronix. Now it is very bouncy.
 

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Opeler
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57 Posts
Tune up time!

I know I'm a caveman but I still like the simplicity of points and the sillyness of setting dwell. My tach starts bouncing when the points need attention. Once everything is set well it's as smooth as silk. I guess one of the really smart folk here might be able to figure out what this all of our symptoms together mean..any takers?
 

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Curve Crazy GT
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399 Posts
Discussion Starter · #9 ·
ya wolf spyder, i just put in a crane cams electronic ignition with a MSD coil. but even before when i had the points it still did the stupid bounce. mabey im so use the the after market one on my monte that is so stiff. i dunno whats wrong.... :mad:

thanks
chris
 

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Super Moderator
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Part of the issue....30+ year old electronics. I've seen GT's with bouncy tachs that 'showed' 6500 rpms, but next to a good known working performance tach I've seen them off by as much as 1300 rpms (7800 rpms in real time!). And the new tach was steady as a rock as well. No matter what model Opel I drive, the OEM tach is one of the first things to go!
 

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Curve Crazy GT
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399 Posts
Discussion Starter · #11 ·
oh i see. thanks i guess the question now is live with it, or does any one know an after market tach, that will bolt right up or little modification to put it were the current one is? most likely no...

thanks
chris
 

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Curve Crazy GT
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Discussion Starter · #12 ·
forgot to say... any one know the diameter of the GT tach?

thanks
chris
 

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O.K. I just took the tach out of Willit?'s instrument panel and did some measuring with my handy dandy Craftsman vernier calipers. Here's what I got: Major diameter of the tach case is 5.065"; the chrome bezel measures 5.250"; and the inside diameter of the mounting hole is right at 4.80". HTH.
 

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Curve Crazy GT
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Discussion Starter · #14 ·
cool

thanks
chris
 
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