Hood Tach wiring with HEI Distributor - Pontiac GTO Forum
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post #1 of 6 (permalink) Old 10-27-2017, 10:01 AM Thread Starter
 
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Hood Tach wiring with HEI Distributor

Hello, I have a factory hood tack on my 1967 GTO and I also have an HEI distributor. The new hood tack came with a wiring harness with mainly a connector with a black, gray and a black and orange wire connected to it. Then there is a short black and orange wire with a connector on one end and what looks to be a ground clip on the other end, about 4". The black and orange wire has a fuse holder on one end and coming out of the fuse holder is a mail connector.

Now from Ame's I have purchased 1 HEI tach wire, which is brown with a female connector on one end and just a connector that looks like it would go inside a plastic connector.

The other wire I purchased from Ame's is a HEI power feed wire. It is a thick red wire with a female connector on one end and again the male connector without the plastic end that would house it.

Now which wires do I use and which wires go where from the tack to the HEI distributor??

I know a complicated question but I know someone out there is smart enough to know the answer.

thank you in advance.

alan

Alan
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post #2 of 6 (permalink) Old 10-27-2017, 09:36 PM
 
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Alan,

I think all you need to do is connect the wire from your tach that would normally go to the coil to the plug on the HEI which should say "Tach" - IF you are using a factory Pontiac HEI distributor. I posted a photo showing a red cap having the "TACH" and "BAT" hook-up. That brown wire with the female end is the one that clips into that slot marked "TACH" on the HEI cap. There will also be a slot next to it that says "BAT" for battery. I posted photo #2 showing how it clips in, but you will only be using the "TACH" plug. The other red connector wire you have is most likely used for the "BAT" terminal on the HEI cap, but you don't need it for your hood tach as you will use your factory wiring (or whatever the instructions say) for all other wires on the hood tach. So what you want to do is to connect/splice the hood tach wire that would normally go to the coil to the end of your brown lead that you purchased and then simply plug it into the slot marked "TACH" and clip it into place. Then hook all your other wires up per factory or whatever the tach directions tell you to do.

I found this in my search: "If you have an HEI distributor with a "Tach Output" you can use the "Tach Output" from the HEI distributor. Due to the high voltage of the signal from the HEI you should use a tachometer filter to prevent damage to the tachometer."

Tachmeter Filter: GM Tachometer Filter. Corvette Tach Filter. and http://www.marshallinstruments.com/pdf/37.pdf

There may be other version/manufactures of this Tach Filter. Never heard of one or used one, but never used a factory hood tach with an HEI or electronic distributor so I can't tell you if you absolutely need it or not, but I would not want to damage my tach either if I did need it. So you might do a little more research on it to see if you need it or not OR contact the seller where you bought your hood tachometer and find out if it is compatible with an HEI or electronic distributor and does not need the tach filter.
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post #3 of 6 (permalink) Old 10-28-2017, 11:07 PM Thread Starter
 
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Thanks for the info but I am not using a factory HEI tach. I am using an aftermarket HEI tach. It was in the car when I purchased it. So just trying to figure out how to wire it. I know that the hood tach that was on the car was very erratic so I purchased a new one. Just don't want to burn it up before I figure out how to wire it.

Any other suggestions would be appreciated.

thanks again
alan

Alan
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post #4 of 6 (permalink) Old 10-29-2017, 01:00 PM
 
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Quote:
Originally Posted by alanmay0 View Post
Thanks for the info but I am not using a factory HEI tach. I am using an aftermarket HEI tach. It was in the car when I purchased it. So just trying to figure out how to wire it. I know that the hood tach that was on the car was very erratic so I purchased a new one. Just don't want to burn it up before I figure out how to wire it.

Any other suggestions would be appreciated.

thanks again
alan
Check on line for a wiring diagram specific to the aftermarket HEI type distributor you have. Often a wiring PDF is available.
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post #5 of 6 (permalink) Old 11-16-2017, 10:10 AM Thread Starter
 
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The HEI I have has no markings or names on it. It was in the car when I purchased it. No clue who made the HEI.
thanks
alan
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post #6 of 6 (permalink) Old 02-22-2019, 05:24 PM
 
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I have a hood tach I bought from THE PARTS PLACE I have and after market HEI disributor Can any one tell me how to wire it IN the wiring instructions it says you will need a TACH ADAPTER MODULE can anyone help me out thanks BILL
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