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Discussion Starter #1
Could anyone pass along any knowledge about what speedometer can or can not be used with the dash tach. I have a 69 Nova that I am putting a console and gauges. The car did not have the console and gauges originally. I have also purchased a tach gauge for the upper left dash position opposite the clock. After reading some info it looks like a speedometer from a non tach dash will not work properly if I hook up the tach ar visa versa. Or something won't work properly. I want to use the original 69 Nova insturment panel and add the tach in the appropriate place. Help please!
 

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You will need to do some re-wiring to get the tach to work. It can be done but you will need a wiring diagram to figure out what wire is what. The easy way is to buy an under the dash wiring harness for the console and also a motor wiring harness for the tach but this will be the costly but easy way out.

Jason
 

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I did the same exact thing you did.
I just ran a seperate jumper wire to the tach to find out which terminal would make the tach move. Then I took a wire and put a terminal on the end and took a small bolt and nut thru the terminal and hooked the wire up to that, then ran the wire to my dist cap hook up (I have HEI) and it works great:yes: I dont have any info on the gauge pod because I have an autometer pod with digital gauges in it
 

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Discussion Starter #4
Thanks for the ideas.

Can anyone tell the reason why a speedometer from a non tach dash will not work when a NOS OEM GM factory tach is installed and hooked up where a tach dash would have had the tach installed? Which is where the fuel gauge was originally in a non tach dash. (Top left) Is it just that the wiring harness will not have the correct wires to the tach terminals or is it a more complex electrical issue of some kind.
 

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I dont see why the speedo wouldnt work because they all had the same mechanical hook up. The tach on the other hand has completly diffrent wiring from the fuel gauge the fuel gauge wires run from the connector in the back of the cluster to the fuel sender and with the tach the wires that would go to the fuel sender now go to the distributor. I hope that answers your question
 

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Just to clarify what stock72Nova stated the speedometer is a mechanical hookup to the speedometer cable off of the transmission. The tachometer is an electrical hookup. The dash lighting circuit lights up the tach and the speedometer.

When I converted my 74 dash from an indash fuel gauge to an indash factory tach setup I removed the fuel gauge, flipped the flexible circuit board up out of the way and then bolted in the tach and connected the flexible circuit board to it using the old connections that were on the original fuel gauge. What then had to be done was the fuel gauge wire off of the harness that plugs into the instrument panel had to be routed to the negative terminal on the coil. On mine I chose a spot to cut the wire that originally went bacj towards the fuel sender and then attached a longer wire to it and routed it through the bulkhead connector on the firewall and then continued routing it and made the connection to the negative terminal on the ignition coil. I was then left with the wire going rearward to the fuel sender unit. This wire was then extended to reach the console fuel gauge.

I'm trying to keep my 74 looking stock and that's why I routed the tach signal wire through the firewall bulkhead connector. I could have also bought or swapped in the correct engine and interior harness but I had donor harness' to get the correct color wires and terminals out of it. A person could also just go through an insulated hole in the firewall.

With all this said, MAYBE the car you have is different but on mine I just did some research as to how I could accomplish what I did. I also bench checked the used factory tach to make sure it was working properly before I did anything to the car. Nothing worse than getting things installed and things then don't work.

Another thing I did on my car was add a speed alert speedometer but this wiring is seperate from everthing else I've told you above.

Jim
 

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Discussion Starter #7
Thanks to Stock72nova and Custom Jim

thank you,

That is the info I needed. Electrical stuff is not my forte' but the way you explained it, I think I'll be able to "get er done" . It is members like you that make this a GREAT site.
 
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