73 Convertible Wiring

[73vertstang]

Hello All!

New to this site and just figured out I posted my question on Talk instead of Tech, what a dumb #$s! I am restoring a 73 convertible, I striped her down to the bare bone had her Soda blasted, replaced the floor pans, both quarter pannels and outer wheel wells, tail light pannel, rear deck pannel. (I should've just bought a new one... Naaaaaa) Having the 351C rebuilt (New cam, pistons, valves and so on) it came with a Holly 4bbl and a edlbrock intake. (Just how much is a 08 convertible???) Now for the problem. I wanted to add the in dash tach and gages. I picked up the gage cluster (tach and speedo) the center bezel cluster (Oil, volts, temp) the under dash wiring to support the above (All out of wrecks, recycling!!!) What I don't know or understand clearly is the engine compartment to the top of the fuse block loom. I understand the original loom won't work the gages. I have NOT been able to find one to replace it (Every yard from east to west and Canada are sick of me) Can the original be modified to support the gages? Thanks!

 

[BarnStang]

THe answer is - maybe. Probably. I've done it on a 70. Found the tech article at the boss302 registry on how to do it. Here is a link to the article, but you better contact the boss302 registry and track down the author and make sure this mod will apply to a 73. I'm not sure it would.
http://www.boss302.com/tach.htm

 

[73vertstang]

Thanks!

Your answer is better then No! I intend to send the wiring out to be refurbished. There is a company out in Cal the specialize in Ford wiring and does Mustang's up untill 1970. They will work on the 73 if I'm able to include the diagrams. I have two sets so far. I was hoping to be able to include the engine harness with the tach and gages and modify it for the convertible top (Easy) now it seems I have to do it the hard way (as always). I'm just not sure what is different between the original and the one with the gages. I've looked parts suppliers and find there is the ALt harness with tach and gages and the gages harness its self. (It has the leads to the three sensors) I'll talk to them again and see if I need to include the two harness as well. Thanks for you reply! Here a couple of shot taken two weeks ago.

 

[BarnStang]

I posted a question at the boss302 registry, but didn't get any responses. I have a 71 vert here in the shop with a factory tach. I'll try to at least get the pinout diagram of the cluster connector. Not sure if that will be enough. It will be a start.
I compared the 70 and 71 wiring diagrams for with tach, and they are of course different.

 

[jikelly]

Ok so you have an original/OEM gauge cluster with a tach to go into your convertible that had the idiot lights?

Well if that is the case then yes you can put that gauge cluster in your vert, but no it wont work with the wiring harness you've got now. I installed an aftermarket tach into my 73, but I also rewired the whole car with a EZ 21 circuit kit. That was fun, not!

Anyway, so I'm not sure if you require an entirely new/different harness or if all that is required is altering the dash wiring and running a tach pickup out to your distributor. I'm sure someone else has to have done this because I know it was #5 on my wish list when I got my 73.

Good Luck!

 

[BarnStang]

The factory tach doesn't work like a modern tach. CHeck out the article I put a link to. You will see the problem. Using a modern tach would be the easy way. THe harness needs to be modified to use the tach cluster.

 

[Gud T.B. Blown]

You can run a factory tach without the proper wiring harness, all you need to do is run a wire to the coil and one to the ignition. Before I swapped wiring harnesses and gauge clusters I was running a tach in a clock gauge cluster. The printed circuit wasn't a perfect fit but it fit enough so that it stayed attached and lit the tach at night.

 

[73vertstang]

Thanks Barnstang and jikelly!

I have the under dasd harness with all the correct plugs (I check by connecting both tach and the gage cluster) I need either to modify the orignal "top of fuse block to engine comp" harness or get same out of a wreck. I saw a guy on Ebay with the complete harness with tach and gages from a 72. Barnstang do you think it would work? 72 and 73 were pretty close. Here another pict of the vert, body almost ready for primer, next week!!!

 

[Gud T.B. Blown]

It should work. I've got a 1971 harness in my '73 and everything works fine.

 

[BarnStang]

Yes it will work. 71-73 should be nearly identical. Yes, you can put a factory tach in your non-factory tach cluster and hook it up. But you can't plug a factory tach cluster into a non factory tach harness. You can, but the gauges go haywire (in a 70 I know...). If you read through that article, on the last page it shows a diagram. THe resistor wire runs thru the tach. THere is no conection to the coil that I know of with a factory tach. THat's why if the tach fails, the car dies. And factory tach owners need to know this to get there car going again. THey have to unplug the tach, and jumper the two prong connector on the harness to complete the ignition circuit.
I tried to get the pinouts on the 71, but just couldn't get to it today. Sorry. I will try next week. If you can get that harness cheap enough, that will solve the problems easily. I would love to develop a swap article to make a non-tach harness work. I think it would be useful to a lot of people. I keep wasting all those hours between midnight and 6am...

 

[Gud T.B. Blown]

On a '71-'73 the car will still run if the factory tach doesn't work. However, if you unplug the tach from the wiring harness that's a different story.
And on a '71-'73 you can't plug a tach cluster into a non-tach wiring harness. The wiring harness cluster plug is too big, it won't fit into the tach cluster.
I've done the wiring harness-gauge cluster swap in my '73 Mach 1 and it was very easy, just plug and play. I didn't even change the underhood harness.

 

[73vertstang]

Hey Guys, won that 72 wiring harness on Ebay. Set me back 350, but it's uncut and complete from headlights to taillights. We'll see when it get here. Thanks everyone for all your input!!!

 

[BarnStang]

That will solve the problem much cleaner.