Hooking up aftermarket tach

silverriff · 02-07-2008, 10:08 AM

As stated in my previous posts, my 1972 cutlass hackjob's previous owner bought some sort of aftermarket tach. It was not working when I drove the car, and when I tapped on the face to see if it was loose or something, the damn thing fell right out of the dash. Not only was it not hooked up, the wire ties we still securing the wires together like it was right out of the box. Long story short, I have never hooked up a tach before. Is there a standard wiring proceedure for doing it? It has to be hooked into the distributor or something....right....??

Maybe someone could recommend a really good detailed assembly manual so I can find this stuff out myself. The Chilton's is not cuttin the mustard.

Oldsguy · 02-07-2008, 12:26 PM

Most tachs have three wires, one for the signal from the distributor, one for ground (might be deleted if tach is grounded via the mount i.e. all metal housing), and one for the illumination lamp. What are the colors of the wires or are they labeled at all? The one for the distributor signal would be the wire that goes from the points to the coil. This is assuming an HEI distributor has not been installed as a modification on the car.

silverriff · 02-08-2008, 08:41 AM

No the standerd distributor is still in there, but I have been thinking about upgrading the ignition system. It is still cold and cruddy here in MD, and it could use some more starting power. When I upgrade to an HEI, is that more/less pain in the butt to hook up a tach?

Oldsguy · 02-08-2008, 11:31 AM

Not easier or harder, just different. I think on an HEI there is actually a wire in the harness specifically for the tach signal but I don't know which one it would be.

silverriff · 02-08-2008, 11:57 AM

Thanks for your help. I am going to be doing some more investigating this weekend, after I get a new distributor. If I have any more dumb newbie questions Ill let you know! -Eric

The_Jeremiah · 02-08-2008, 11:59 AM

My HEI in my cutlass has a specific point labeled TACH, and thats where you feed the positive wire into the distributor for the tach. That odd that you found that, best of luck to you.

Kahuna · 04-13-2008, 08:38 PM

Try these Sunpro instructions:

http://www.sunpro.com/publish/2007/0...lish_16472.pdf

The wiring diagram should be valid for most aftermarket tachs. I installed a Sunpro tach in my '62 Olds (steering column). I just followed the instructions to the letter and it works great.

silverriff · 04-14-2008, 05:47 AM

Awsome! Thanks Paulie! I just got finished wiring up my new dash harness yesterday, you sent me that at the perfect time. It also looks a lot easier than I thought it would be. Thanks again!

-Eric

Redog · 04-14-2008, 07:00 AM

HEI should have a port on the cap for the tach.

Points you connent to the neg side of the coil

02-07-2008, 10:08 AM	#1 (permalink)
silverriff Member Join Date: Feb 2008 Posts: 30	Hooking up aftermarket tach As stated in my previous posts, my 1972 cutlass hackjob's previous owner bought some sort of aftermarket tach. It was not working when I drove the car, and when I tapped on the face to see if it was loose or something, the damn thing fell right out of the dash. Not only was it not hooked up, the wire ties we still securing the wires together like it was right out of the box. Long story short, I have never hooked up a tach before. Is there a standard wiring proceedure for doing it? It has to be hooked into the distributor or something....right....?? Maybe someone could recommend a really good detailed assembly manual so I can find this stuff out myself. The Chilton's is not cuttin the mustard.

02-07-2008, 12:26 PM	#2 (permalink)
Oldsguy Administrator Join Date: May 2004 Location: Lees Summit MO Posts: 2,553	Most tachs have three wires, one for the signal from the distributor, one for ground (might be deleted if tach is grounded via the mount i.e. all metal housing), and one for the illumination lamp. What are the colors of the wires or are they labeled at all? The one for the distributor signal would be the wire that goes from the points to the coil. This is assuming an HEI distributor has not been installed as a modification on the car. __________________ Dan '46 2 door

02-08-2008, 11:31 AM	#4 (permalink)
Oldsguy Administrator Join Date: May 2004 Location: Lees Summit MO Posts: 2,553	Not easier or harder, just different. I think on an HEI there is actually a wire in the harness specifically for the tach signal but I don't know which one it would be. __________________ Dan '46 2 door

02-08-2008, 11:59 AM	#6 (permalink)
The_Jeremiah Senior Member Join Date: Jul 2007 Posts: 218	My HEI in my cutlass has a specific point labeled TACH, and thats where you feed the positive wire into the distributor for the tach. That odd that you found that, best of luck to you. __________________ 69 Cutlass 4 door. Built 350 inside, grandma's grocery getter outside. Best sleeper in disguise.

04-13-2008, 08:38 PM	#7 (permalink)
Kahuna Junior Member Join Date: Apr 2007 Location: Toronto, Canada Posts: 19	Try these Sunpro instructions: http://www.sunpro.com/publish/2007/0...lish_16472.pdf The wiring diagram should be valid for most aftermarket tachs. I installed a Sunpro tach in my '62 Olds (steering column). I just followed the instructions to the letter and it works great. __________________ Paulie '62 Dynamic 88 - Holiday Coupe

02-08-2008, 08:41 AM	#3 (permalink)
silverriff Member Join Date: Feb 2008 Posts: 30	No the standerd distributor is still in there, but I have been thinking about upgrading the ignition system. It is still cold and cruddy here in MD, and it could use some more starting power. When I upgrade to an HEI, is that more/less pain in the butt to hook up a tach?

02-08-2008, 11:57 AM	#5 (permalink)
silverriff Member Join Date: Feb 2008 Posts: 30	Thanks for your help. I am going to be doing some more investigating this weekend, after I get a new distributor. If I have any more dumb newbie questions Ill let you know! -Eric

04-14-2008, 05:47 AM	#8 (permalink)
silverriff Member Join Date: Feb 2008 Posts: 30	Awsome! Thanks Paulie! I just got finished wiring up my new dash harness yesterday, you sent me that at the perfect time. It also looks a lot easier than I thought it would be. Thanks again! -Eric

04-14-2008, 07:00 AM	#9 (permalink)
Redog Alero Chapter Secretary Join Date: Aug 2006 Location: Newtown, PA Posts: 632	HEI should have a port on the cap for the tach. Points you connent to the neg side of the coil __________________ Me 2000 Alero running 14's 1985 Delta 88 w/1968 350 rocket 2005 Nissan Altima (her's)

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