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Discussion Starter #1
The car = 1970 Standard coupe, 351C 4V 4 speed.

A while ago I used "The RKTMN" (I think that's spelled right) method for hooking up my tach. It worked great!! Now I have no tach again and the ONLY CHANGE has been the deletion of the ported vacuum switch. I accidentally broke it when I was changing out the water pump. So I'm left with no tach BUT the car still runs great.

What should I hook that connector to, to keep the tach working. The basic diagram is the same as the Curbs one.

Thanks, Paul
 

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Educate me, #1, what is THE RKTMN? and what does vacuum have to do with a tach?
 

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Hi Paul. towcat is right - a vacuum port will have no effect on your tach. Perhaps something else got cut or disconnected during the waterpump change. Are we talking about a factory original tach wired into the ignition or one of my conversion tachs?
 

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Hi Paul. towcat is right - a vacuum port will have no effect on your tach. Perhaps something else got cut or disconnected during the waterpump change. Are we talking about a factory original tach wired into the ignition or one of my conversion tachs?
It's a factory tach. When I first wired it up it worked and now, since the vacuum port delete it doesn't.

I'm pretty sure the tach has power due to just a slight movement when I start the car so it's like it's not getting the signal.

Where would I pick up the signal from and which wire would I attach it to? I've tried various wiring scenarios with the only result being a no spark condition. The motor cranks but it doesn't start. Once I put the wires back the way the way they were everything works except for the tach.
 

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The factory tach connects to the + side of the coil. The OEM wiring has the tach wired between the ignition switch and the "pink" resistor wire. The only thing you can disconnect under the hood that will effect the tach is the wire to the + side of the coil. If that is cut/broken/missing the car will not run.
It is possible for the movement portion of the tach to die and the circuit side still work so the car will run but the tach won't work. It sounds like your movement called it quits - it's just coincidence that it happened when the waterpumop was being replaced.
 

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Educate me, #1, what is THE RKTMN? and what does vacuum have to do with a tach?
Sorry for my stupidity, now I know about the Rocket man
 

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:lol: No problem towcat. :D
 
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