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| | | | Joined: Feb 2011 Posts: 59 Wrench Fetcher | | Wrench Fetcher Joined: Feb 2011 Posts: 59 | | | | | | Joined: Nov 2009 Posts: 239 'Bolter | | 'Bolter Joined: Nov 2009 Posts: 239 |
Typically there are 3 contact points on a tachometer... power, ground and sense. The power is the hot lead (+12 volts) the ground is the ground and the sense lead goes to the negative side of the coil.
On your tachometer (which is set to 8 cylinders), here is what I see. The two top terminals are isolated from the case by the plastic stand-offs. This implies they are not the ground lead. That leaves the bottom terminal as the ground. Under the top right terminal is the word “IGN”, which means ignition. That appears to imply the +12 volt (power) lead. The one remaining is the sense terminal which goes to the negative side of the coil. This is my belief. Others may have a different point of view.
It would be easier to analyze if the wires weren’t connected and we could see what was behind the red wire.
In all honesty, that red wire implies a hot terminal but it is not connected to the “IGN” side, which gives me some pause.
When I die, I want to go peacefully like my Grandfather did, in his sleep -- not screaming, like the passengers in his car.
-Unknown-
| | | | | Joined: Feb 2011 Posts: 59 Wrench Fetcher | | Wrench Fetcher Joined: Feb 2011 Posts: 59 | Thanks for the info di1953gmc. You are correct the upper right is IGN and the lower left is NEG Ground. One thing that I am confused about is that someone had a jumper wire between the top two studs. I also plan to switch it to 6 clinders.
Thanks Larry | | | | | Joined: Nov 2009 Posts: 239 'Bolter | | 'Bolter Joined: Nov 2009 Posts: 239 | Larry,
A jumper between the top two terminals would not make sense to me. Are you sure the tach works?
When I die, I want to go peacefully like my Grandfather did, in his sleep -- not screaming, like the passengers in his car.
-Unknown-
| | | | | Joined: Feb 2011 Posts: 59 Wrench Fetcher | | Wrench Fetcher Joined: Feb 2011 Posts: 59 | I hooked up the tach using test leads and it spiked the tach to max rpm. Any more ideas??? | | | | | Joined: Nov 2009 Posts: 239 'Bolter | | 'Bolter Joined: Nov 2009 Posts: 239 | Remove that jumper!! Hook the (+) lead to the IGN terminal, the (-) lead to the ground. The tach needle shouldn't move until you hook the sense side to the coil and start the engine up.
When I die, I want to go peacefully like my Grandfather did, in his sleep -- not screaming, like the passengers in his car.
-Unknown-
| | | | | Joined: Feb 2011 Posts: 59 Wrench Fetcher | | Wrench Fetcher Joined: Feb 2011 Posts: 59 | di1953gmc
I had the jumper off when I tryed it. I tryed again today to make sure I had it hooked up correctly but no luck, the needle still spiked. I tryed going from 8,6 and 4 on the setting. Mybe my tach is no good!!!!
Larry
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