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Turbo6inKY

Getting your early 240Z tachometer working with an MSD 6 Series ignition.

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If you read through the MSD site you'll see that the 6AL is essentially the same as the 6A except for the addition of some rev limiters and internal upgrades.  That's why the 6A is NLA.  But the external wiring is exactly the same (Page 4 of the instructions for both the 6201 and 6425 is identical).  The instructions for the 8910 and the 8921 show that the ignition control used doesn't really matter, it's the tach type that determines which to use.

 

And, for anyone that wanted to dig deeper, it really looks like the 8910 is just a condenser/capacitor in a fancy package, and the 8921 is just a small amplifier.  Probably why some people get their early tachs to work by adding a few more loops to the circuit in the tach.  You get a stronger magnetic field with more current or more windings.

 

http://www.msdignition.com/instructiondownload.aspx

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So I need to get wither the 6a or the 6al to work with the 8920 tach adapter? Also had a question of that wire to wire to a positive 12v when key is turned on. I was gonna wire it to the temp sensor cause that's a 12v source and when key is on. Does that seem like it will work? In a little bit I may be able to post pictures. So far I've been trying to do this with only the 8920 adapter but if I'm reading right new zed is saying I need either the 6al or the 6a.

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3ryce, what exactly are you trying to do? You haven't provided any information on your ignition system. Why do you think you need a tach adapter? The fact that you're asking if you need an MSD 6AL to use a tach adapter tells me you need to stop and do a lot of reading before you go any further. You need a tach adapter if you have an MSD 6AL. You don't add an MSD 6AL because you have a tach adapter.

 

Or, are you asking if the tach adapter only works with the 6AL? I can't tell.

 

Also, no, you can't use the temperature sensor wire as a 12V source.

 

Nigel

Edited by Nigel

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Ok I am sorry I have not mentioned in previous post that I have a msd blaster 2 ignition coil. I thought I had, was prob somewhere else. Tach works, however not with the msd ignition coil. Im just trying to get my tach to work. Ive got a 6/73 240z. 4 speed. I have the 8920 adapter, I cant tell if I need the 6A with it or not. I also just saw the 6AL 2. Looks pretty nifty.

Edited by 3ryce

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I've seen other setups with the resistor and msd coils. After some rereading this somemore. Ive gathered that I need the 6A/AL for one way to make the tach work. Im looking for other solutions. Thats what im trying to ask for. I do not have the OG coil either.

Edited by 3ryce

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2wg5gl2.jpg

 

Connect the end of the white wire (red arrow) to the red wire from the adapter.   Splice the other end to the hot wire already connected to the tach.   It doesn't matter which end of the white wire is connected were.   It works both ways.

 

This is a '71 tach.

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If you don't have an Multi Spark Discharge box (MSD 6AL, Crane Hi-6S, ect) you don't need the adapter.

 

You only have an aftermarket coil, so it should be wired up the same as OEM and your tach should work properly.   Somewhere along the line, your tach is not getting any type of signal from the coil.   You need to go thru your wiring and figure out what isn't hooked up properly.

 

 

You don't need to go out and buy an MSD box to make it work.   You could, but unless you are building a racing motor you don't need it and it would just be a waste of money.

Edited by Apollyon12

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Hope someone can help!! I have a 73 240z with L28, Malory unllite, msd coil (that requires no ballast). Tach is working fine. I installed 6al now no tach. So I been reading through threads and found I need a tach adaptor. I installed the msd 8920 and now everything works... So I think!! At idle it works. Rev it up it works!! Redline it still works!!! Problem occurs once I start driving. I would take off and tach seems to work fine than once I get up to speed and change gears it would go back up normally than just drop to zero and stay there till I'm almost to a complete stop. When it drops to zero it's not at any specific rpm or speed. Any help would be greatly appreciated thanks!!

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Hope someone can help!! I have a 73 240z with L28, Malory unllite, msd coil (that requires no ballast). Tach is working fine. I installed 6al now no tach. So I been reading through threads and found I need a tach adaptor. I installed the msd 8920 and now everything works... So I think!! At idle it works. Rev it up it works!! Redline it still works!!! Problem occurs once I start driving. I would take off and tach seems to work fine than once I get up to speed and change gears it would go back up normally than just drop to zero and stay there till I'm almost to a complete stop. When it drops to zero it's not at any specific rpm or speed. Any help would be greatly appreciated thanks!!

 

Ed,

 

Check the charging system. Specifically, look for over-charging. A high voltage condition while driving could be upsetting the tach or 8920. If the charging system checks ok the next likely suspects are the 8920 and the tach.

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Thanks for the reply! I'll check the charging system tonight. By the way I'm running a internal voltage regulator alternator if that matters. Also I've been doing more research and I found some people added a diode or resistor. I haven't done this. So I'm reading up on it but I don't see where I need to add this.

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So I am looking at this solution for my set-up. Running MS3 with LS1 coils on an original 71 current tach. The directions from Turbo6inKY  above says to hook the black/white stripe up to a 12 volt ignition source. But originally the black/white going to the tach was hooked to a 12volt ignition source, so why not use this right?. Maybe over thinking this, but want to be sure.    

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So....you are saying that this approach isnt right?

 

Dan,

I checked the wiring on my '72 this weekend. Here's what I've got:

Black/white wire(previously coil +) connected to red wire from tach adaptor.
Green/white wire connected to swithed +12V.

I hope this helps.

graemlins/cheers.gif 
Don 

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Bumping this thread a bit but I wanted to add.

 

For people with older Current sensing tachs and 6x coilpacks you can simply pull the power from the old distributor terminal. The tach will sense the current draw on the COPs. Worked fine for my toyota 1zz coils.

 

I learned this of course after i had already wired them all on a separate line haha.  

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