Factory Tach hookup to MSD 6AL

[JCB-69CJ 11]

Hi,

I have been searching the Forum without luck for information on hooking up a factory tach to my MSD 6AL.

 

When I got the car the MSD was already installed and the tach disconnected. I dont know if the tach is a Voltage triggered or a Current triggered type. Searching the car shop manuals I have didn't give me the info I needed.

 

The MSD instructions mentions these 2 types and possibly needing anMSD 8920 adapter depending on what type of tach it is.

 

Has anybody done this before and can guide me thru the process.

 

Thanks in advance, JB

[sixty9cobra 10]

I just installed one in mine you need the msd tach adapter and wire it for a current driven tach not a voltage tach like the gm uses. Go to the msd site they have the instructions online its like four wires but you need to get to the connecter for the tach. look here http://www.msdignition.com/downld3.htm

[JCB-69CJ 11]

Thanks for the info. I knew somebody out there had to have done this before. I just ordered the adapter from summit. Thanks again.

 

JB

[sixty9cobra 10]

I just did it last week so its fresh in my mind. I even ran the white wire from the msd into the console for a kill switch. You just have to bypass the factory wiring to the tack. I ran 12v from the key directly to the msd and the tach adaptor. My friend has a msd tester which replaces the distributer simulates the engine. I had my 428 up 8000 rpm really cool. Tach seems to be pretty accurate according to the read out on the tester. Now i just need to put my motor back in and get some wheels and I will be ready for some cruizin.

[JCB-69CJ 11]

Hey Sixty9Cobra, Just noticed your from LI, same here. Maybe I will run into you sometime, lol , at a car meet I mean.

I go to the sunday Oak beach Inn during the summer and to a thursday night thing in my local town Oakdale.

[sixty9cobra 10]

Looks like we have similar taste in cars. Im from Mt Sinai where on LI are you?

[Solo2 0]

Here is all the info I have collected over the years on this topic from many different forums.

Good Luck!

Part 1:

tach adapter

 

The black wire goes to a ground,white goes to the plug-in on the 6AL box.You don't use the purple one and the red wire goes to the red wire from the ignition switch.

Hope this helps. D.Thompson

Tach hook-up

 

The tach is hooked between the ignition and the positive side of the coil. The wire goes from the ignition to the tach, and from the tach to the coil. You will need a tach adapter to hook up an MSD.

Frank

How did you hook up your tach? The factory tach is hooked up to the ignition switch. The current goes from the switch to the tach and then to the positive side of the coil. You have to use the tach adapter with the MSD. I don't remember the complete part number, but it ends with 10. I will check one of my cars when I get to my shop later today

bosscougars

 

Needs a Job

Eliminator registrar

Posts: 2176

posted December 29, 2003 11:19 AM

Tach Adapter

 

They did give you the wrong information. The first one that I ever got was an 8920 and it screwed up my MSD. Got on the phone with a tech guy with MSD and he told me I needed the 8910 adapter. Tried it as instructed and it worked great. That was a few years ago and I have since installed MSD's on six of my cars with factory tachs including my Boss 9 that I just finished and they all work fine. The 8910 is a piece of cake to hook up compared to the 8920. The local O'Reilly auto parts store carries them. Check with your local parts store.

Frank

 

 

Do you have a fax available?If so, I will fax you a copy of the adapter info and the instructions. It specifies, the part #8910 is designed for non-current limiting(originally equipped with a ballest resistor) such as breaker points or optical triggered distributors.

The tech guy you talked to is WRONG, WRONG, WRONG.

If you'd like to call, my number is 918-655-3352. I have this application on six Ford factory tach cars and all work properly.

Frank

Dallas-----You need the 8910 tach adapter. It is easy to hook up. If you have any questions call me. I have MSD 6AL'S on six factory tach cars. Just put one on the Boss 9.

If you look down in the corner where the battery usually is you will see it looking at you[barely].

All of the answers you got so far are correct. You must remember electrical technology in 1970 is not the same as today. If you are using the MSD and the Ford tach in the dash a converter is required. If you are using the current technology tach it can be wired from the quick disconnect resessed terminal on the side of the MSD box.

Tach hook-up

 

With an aftermarket electric tach, the tach signal wire should be hooked to the tach output on the side of the MSD box. If it had been hooked ANYPLACE else or there had been a tach adapter used when it was not needed, it could have changed the voltage on the MSD tach output to approx. 12 volts and will not work. Check the voltage on the tach output and if it is more than 3-5 volts, it will have to be sent back to MSD to be repaired.

tach adapter

 

grabberblue,

 

I have that part right here and ordered it via Franks instructions(from earlier talks on this subject) from Summit. I have yet to install it but hope to get some time soon. MSD part # 8910. I'm still debating on where to hide it. Kind of a bigger adapter than I was expecting. About 4.5" x 2.5" x 2" thick and big mounting screws. Good luck!

____________

I have #8920 Tach Adapter. The wires out of the adapter go as follows; Black goes to a ground (make sure this is a good ground) White goes to the plug-in on the 6AL box, Purple is dead (don't use) Red to the red wire from the ignition switch. I hope this helps........Terry

bosscougars

 

Needs a Job

Eliminator registrar

Posts: 2176

posted October 23, 2002 11:02 AM

Correct tach adapter

 

GS was right. It has been discussed on the old board. The directions with the MSD for our cars is wrong. I had a long talk with a tech expert in El Paso and we agreed the correct adapter is part number-8910. I have them on five cars and they work great. It is a simple hook-up, two wires, and you don't have to go under the dash. If you have any questions, just ask. bowers@clnk.comThat's what we're here for.

 

 

 

[Solo2 0]

Part 2:

tach adapter

 

The black wire goes to a ground,white goes to the plug-in on the 6AL box.You don't use the purple one and the red wire goes to the red wire from the ignition switch.

Hope this helps. D.Thompson

Tach hook-up

 

The tach is hooked between the ignition and the positive side of the coil. The wire goes from the ignition to the tach, and from the tach to the coil. You will need a tach adapter to hook up an MSD.

Frank

How did you hook up your tach? The factory tach is hooked up to the ignition switch. The current goes from the switch to the tach and then to the positive side of the coil. You have to use the tach adapter with the MSD. I don't remember the complete part number, but it ends with 10. I will check one of my cars when I get to my shop later today

bosscougars

 

Needs a Job

Eliminator registrar

Posts: 2176

posted December 29, 2003 11:19 AM

Tach Adapter

 

They did give you the wrong information. The first one that I ever got was an 8920 and it screwed up my MSD. Got on the phone with a tech guy with MSD and he told me I needed the 8910 adapter. Tried it as instructed and it worked great. That was a few years ago and I have since installed MSD's on six of my cars with factory tachs including my Boss 9 that I just finished and they all work fine. The 8910 is a piece of cake to hook up compared to the 8920. The local O'Reilly auto parts store carries them. Check with your local parts store.

Frank

 

 

Do you have a fax available?If so, I will fax you a copy of the adapter info and the instructions. It specifies, the part #8910 is designed for non-current limiting(originally equipped with a ballest resistor) such as breaker points or optical triggered distributors.

The tech guy you talked to is WRONG, WRONG, WRONG.

If you'd like to call, my number is 918-655-3352. I have this application on six Ford factory tach cars and all work properly.

Frank

Dallas-----You need the 8910 tach adapter. It is easy to hook up. If you have any questions call me. I have MSD 6AL'S on six factory tach cars. Just put one on the Boss 9.

If you look down in the corner where the battery usually is you will see it looking at you[barely].

All of the answers you got so far are correct. You must remember electrical technology in 1970 is not the same as today. If you are using the MSD and the Ford tach in the dash a converter is required. If you are using the current technology tach it can be wired from the quick disconnect resessed terminal on the side of the MSD box.

Tach hook-up

 

With an aftermarket electric tach, the tach signal wire should be hooked to the tach output on the side of the MSD box. If it had been hooked ANYPLACE else or there had been a tach adapter used when it was not needed, it could have changed the voltage on the MSD tach output to approx. 12 volts and will not work. Check the voltage on the tach output and if it is more than 3-5 volts, it will have to be sent back to MSD to be repaired.

tach adapter

 

grabberblue,

 

I have that part right here and ordered it via Franks instructions(from earlier talks on this subject) from Summit. I have yet to install it but hope to get some time soon. MSD part # 8910. I'm still debating on where to hide it. Kind of a bigger adapter than I was expecting. About 4.5" x 2.5" x 2" thick and big mounting screws. Good luck!

____________

I have #8920 Tach Adapter. The wires out of the adapter go as follows; Black goes to a ground (make sure this is a good ground) White goes to the plug-in on the 6AL box, Purple is dead (don't use) Red to the red wire from the ignition switch. I hope this helps........Terry

bosscougars

 

Needs a Job

Eliminator registrar

Posts: 2176

posted October 23, 2002 11:02 AM

Correct tach adapter

 

GS was right. It has been discussed on the old board. The directions with the MSD for our cars is wrong. I had a long talk with a tech expert in El Paso and we agreed the correct adapter is part number-8910. I have them on five cars and they work great. It is a simple hook-up, two wires, and you don't have to go under the dash. If you have any questions, just ask. bowers@clnk.comThat's what we're here for.

 

 

 

[Solo2 0]

Part 3:

Finally, start with the engine won't shut off I had to add the diode to the wiring harness at the regulator as directions show to stop the feeback of the regulator energizing the msd. Works great now.

In it's most simple form we had to use the wiring diagram from the 8920 current tach and apply that to the 8910 adapter. After a few hours showing my buddy (Dale) the posts from here about the tach and the msd we were almost ready to go to the 8920 tach adapter and try that. The 8910 adapter diagram doesn't make sense to us and we had to treat the tach as a seperate circuit on it's own. In the end what we found was to disconnect the tach harness from the dash wiring, get another mating plug and supply ignition key power to the red wire on the tach wiring going to the tach. Then the blck wire coming out of the tach goes to the red wire of the 8910 tach adapter. From there the white wire goes from the tach adapter to the Tach output of the msd box. Another way which is basically the same is to leave your dash harness attached (because ignition power is there anyways) to the tach and the pink wire which is no longer used with the msd would be the one to go to the red wire of the adapter and from adapter to the tach output of the msd. Although I did not use this last method jumping from the pink wire which is a resistor wire may cause a problem with the tach working properly as I didn't try this method. If anyone has any other method feel free to add comments

The wirig diagram for the 8910 uses the white wire from the msd ignition pickup to complete the circiut of the tach which I don't understand how that works, so we just ended up going from ignition through to tach through adapter to tach output on msd. Thanks to Dale for his help, as two heads can be better than one with these electrical gremlins and I hope this helps...

The way I'm reading it, he's running it almost the way MSD says, but running the tach on a standalone circuit and not picking up the signal from the coil, but using the tach port.

 

Basicly it looks like this:

 

B+------->TACH<---------->R --[8910]-- W<-------->MSD tach port.

 

Next time I'm at a parts store, I'll pick up an 8910 and check this out. It makes more sense to me than to pull the tach signal off the coil, which has multiple sparks below 3000 RPM. This multiple spark is why you use the tach port in the first place. My 6AL renders my Snap-On digital timing light useless, I have to use an old style dial back light.

[Legion 10]

Looks like something that should go in the Wiki....:whistling:

[fvike 173]

Hey, Solo2, in another tach tread you told me about the resistance wires needed for making a factory tach work in a non-tach car.

 

And here is the reason why, there are three (3) interior resistor wires in the tach wiring hardness vs. the regular non-tach wiring which only have two internal resistor wires. The tach wiring needs that third resistor in order to work properly.

This is what I published years ago on this forum:

 

"Only the ones who like me have converted the non-tach wiring to the tach wiring by disassembling the entire wiring harness and at one wire at a time completely rewire the non-tach harness to the tach harness, including the pain-staking job of relocation the pin locations and slots at the dash cluster printed circuit board.

 

These values were never published and it took me five years back in 1978 to get FORD to unlock "THE" blueprints from their vaulets

All values are 10% tolerances resistance."

The three (3) interior resistor wires that is needed for the tach wiring harness:

 

1. 16A (PINK) = 1.5 ohms

 

2. 30A (Violet) = 8.5 ohms

 

3. 904 (Violet) = 1.5 ohms

 

I've got my tach repaired, and have a Crane HI-6 CD unit. I hooked up and MSD 8920 tach adapter. Did the current triggered install, not using the purple wire. I thought my tach was kinda slow, so I disconnected the tach adapter, as I don't want to burn my tach trafo again. Should it work now, or do I still need to run one of those resistance wires? Or is the MSD-8920 wrong, and I should have the MSD-8910?

[Solo2 0]

I do not have any experience in using the msd unit & msd adapter with the tach.

I only know this: Both Tachman and I agree, you need that resister wire to control the current going to the small transistors in the tach, otherwise they get to much current and burn up. More like a +$200 repair job for replacing the burnt transistors and diodes.

My $0.02

[fvike 173]

Ok, as I wrote earlier, I tried the MSD-8920, but it was slow. My car isn't a original tach car. Gonna try the MSD-8910 just for the heck of it, it's only $26 I think. I'll get back to you and let you guys know how it works....

[Solo2 0]

Here is what I have on the 8910 from the archives:

I hope that this works for you........

 

Finally, start with the engine won't shut off I had to add the diode to the wiring harness at the regulator as directions show to stop the feeback of the regulator energizing the msd. Works great now.

(In it's most simple form we had to use the wiring diagram from the 8920 current tach and apply that to the 8910 adapter. After a few hours showing my buddy (Dale) the posts from here about the tach and the msd we were almost ready to go to the 8920 tach adapter and try that. The 8910 adapter diagram doesn't make sense to us and we had to treat the tach as a seperate circuit on it's own. In the end what we found was to disconnect the tach harness from the dash wiring, get another mating plug and supply ignition key power to the red wire on the tach wiring going to the tach. Then the blck wire coming out of the tach goes to the red wire of the 8910 tach adapter. From there the white wire goes from the tach adapter to the Tach output of the msd box. Another way which is basically the same is to leave your dash harness attached (because ignition power is there anyways) to the tach and the pink wire which is no longer used with the msd would be the one to go to the red wire of the adapter and from adapter to the tach output of the msd. Although I did not use this last method jumping from the pink wire which is a resistor wire may cause a problem with the tach working properly as I didn't try this method.)

The wirig diagram for the 8910 uses the white wire from the msd ignition pickup to complete the circiut of the tach which I don't understand how that works, so we just ended up going from ignition through to tach through adapter to tach output on msd. Thanks to Dale for his help, as two heads can be better than one with these electrical gremlins and I hope this helps...

The way I'm reading it, he's running it almost the way MSD says, but running the tach on a standalone circuit and not picking up the signal from the coil, but using the tach port.

 

Basicly it looks like this:

 

B+------->TACH<---------->R --[8910]-- W<-------->MSD tach port.

 

Next time I'm at a parts store, I'll pick up an 8910 and check this out. It makes more sense to me than to pull the tach signal off the coil, which has multiple sparks below 3000 RPM. This multiple spark is why you use the tach port in the first place. My 6AL renders my Snap-On digital timing light useless, I have to use an old style dial back light.

[GOTMACH 10]

I just installed one in mine you need the msd tach adapter and wire it for a current driven tach not a voltage tach like the gm uses. Go to the msd site they have the instructions online its like four wires but you need to get to the connecter for the tach. look here http://www.msdignition.com/downld3.htm

How exactly did you wire yours?

[1969_Mach1 335]

I've used the MSD 8920 tach adapter for factory tachs with MSD ignition systems.  Simply follow the instructions for "current triggered tachometer".