Tach Troubleshooting - Team Camaro Tech
Electrical & Wiring Troubleshooting electrical.

 
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post #1 of 6 (permalink) Old Apr 4th, 08, 12:15 PM Thread Starter
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Alan
 
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Tach Troubleshooting

So I am out driving the 69 yesterday when the tach suddenly won't climb above 3500rpm. It just gets up to 3500 and stops dead even though the motor continues to wind up. I removed the lens and the needle moves freely thruout it range with my finger. The tach reads fine below 3500 rpm.

Interestingly, it is a 7000 rpm tach which is 2x3500.
Any ideas?

alan

Last edited by alanrw; Apr 4th, 08 at 03:59 PM.
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post #2 of 6 (permalink) Old Apr 4th, 08, 07:24 PM
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Len Barron
 
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Re: Tach Troubleshooting

Quote:
Originally Posted by alanrw View Post
So I am out driving the 69 yesterday when the tach suddenly won't climb above 3500rpm. It just gets up to 3500 and stops dead even though the motor continues to wind up. I removed the lens and the needle moves freely thruout it range with my finger. The tach reads fine below 3500 rpm.

Interestingly, it is a 7000 rpm tach which is 2x3500.
Any ideas?

alan
Factory/OER Tach? HEI?

Len
67 SS-350 Convert.
406/200r4/12b 3.73's Truetrac

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post #3 of 6 (permalink) Old Apr 4th, 08, 08:03 PM Thread Starter
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Alan
 
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Re: Tach Troubleshooting

Stock Factory tach Points and condenser distributor.

alan
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post #4 of 6 (permalink) Old Apr 5th, 08, 02:03 PM Thread Starter
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Alan
 
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Re: Tach Troubleshooting

Turned out the dayglo orange needle was hitting the face plate mounting screw. Quick minor adjustment and the world is safe again.

alan
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post #5 of 6 (permalink) Old Apr 5th, 08, 05:46 PM
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Re: Tach Troubleshooting

That's interesting...thanks Alan. Good to know it wasn't a flyback voltage induced reverse bias breakdown of the zener diode in the pi filter

Dave
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post #6 of 6 (permalink) Old Apr 6th, 08, 10:02 AM Thread Starter
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Alan
 
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Re: Tach Troubleshooting

LOL Dave. But what I discovered is that that needle is stamped out of really really thin aluminum. I put a kink in it which took 15 minutes to remove. The best thing to do is to remove (carefully) the face plate and then carefully bend the spring that the orange indicator attaches to. This is really fine watchmaker level stuff. Put the 5 lb "persuader" back in the drawer. Fine tweezers rule the day on this one.

To remove the faceplate, I used those really fine hobby screwdrivers. Keep pressure down on the screw because you don't want the screw driver to slip and booger up the screw. This is one that is best done at the kitchen table, if one of those screws gets loose in the garage, it will fall off into the 4th dimension, never to be seen again.

alan
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