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66 Satellite with factor tach and dreaded MSD ignition box

AR67GTX

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A new-to-me car with MSD and Chrysler electronic distributor. Supposedly they mounted a MSD adaptor to get the factory tach working before shipping the car to me. Well, the tach is active - bounces back and forth between 5 and 6 thousand steadily. I don't see an adaptor up front near the MSD ignition box where I sort of expected it. Is there someplace else likely where I should look? Under the dash? Is the factory tach typically just dead without the MSD adaptor? Or are the bouncing between 5 and 6 thousand typical of needing an adaptor with the electronic ignition (I'm doubting it)?

I'll call the dealer tomorrow to see what their service tech says.
 
0K - did some more research and my mopar electronic distributor is being powered by the green and violet wires from the MSD box. The be white wire is not connected to anything and it is what should be connected to the tach adaptor so the information I was given that one had been installed appears incorrect. I think I need an MSD #8920 tach adaptor to restore the operation of the console tach in my 66 - can anyone tell me if this sound correct?
 
Any opinion on whether I would be better off to just ditch the MSD box (whose name I usually associate with May Suddenly Die) and just install a Chrysler orange box and harness? Does a mid 60s factory tach generally work with it?
 
Any opinion on whether I would be better off to just ditch the MSD box (whose name I usually associate with May Suddenly Die) and just install a Chrysler orange box and harness? Does a mid 60s factory tach generally work with it?
I picked up a used MSD for $50 because of unreliability with the orange boxes. I've been using it for several years now with no problems.
 
Been running an MSD 6 analog box with MP distributor since 1995. Now I hear the newer MSD digital boxes aren't as reliable, but id take a chance on them over the Mopar orange boxes..
 
That's always an option and one I've been considering. The tach is jumping constantly from 5 to 6 thousand but the green wire is not even hooked up to the coil so I'm not sure what is driving it. The shop manual isn't much help as my 67 one shows a tach sending unit whereas the 66 one does not show a tach sending unit. Did they change tach unitss from 66 to 67? Sort of concerned I could spend $80 on an MSD adaptor and find out the tach still needs to be sent off for work. We have a guy here in Arkansas that works on old factory tachs so maybe I should just send it over to him and see what he thinks.
 
That's always an option and one I've been considering. The tach is jumping constantly from 5 to 6 thousand but the green wire is not even hooked up to the coil so I'm not sure what is driving it. The shop manual isn't much help as my 67 one shows a tach sending unit whereas the 66 one does not show a tach sending unit. Did they change tach unitss from 66 to 67? Sort of concerned I could spend $80 on an MSD adaptor and find out the tach still needs to be sent off for work. We have a guy here in Arkansas that works on old factory tachs so maybe I should just send it over to him and see what he thinks.
Start a email dialog with rt-eng.com.
 
Start a email dialog with rt-eng.com.
OK - thanks. I will do that as soon as I verify if this is a 66 tach with a sending unit, or a later, integrated one.
 
The tach on a 66 Charger does have a factory adapter. I don't know about the Plymouth.
Is it a console mounted tach?
 
It is a factory console tach - but I haven’t investigated to see if it’s a transplant from a later year yet.
 
OK - think I've finally figured out what I have. It is a 66 tach unit that uses a remote sending unit. I pulled the sending unit and discovered it has a new circuit board in it that says is MSD compatible. The board is from Mr. Heaterbox.com - which I think is Canadian.

mrheaterbox-brochure-2019.pdf (premiumdashdecals.com)

So, looks like I have all the parts I need - I just need to figure out how to wire it. Does anyone have any wiring schematic info for an MSD unit powering an MSD-compatible factory tach (with new circuit board)?

Does the MSD white trigger need to be connected to the green wire that used to run between the neg coil and tach harness?

Are the wire connections between the sender and the tach the same? I ask because the new circuit board and the tach wiring have some strange labeling provided by a prior owner. Front C-S and rear C-S. No idea what C-S stand for but I see the same lettering on the replacement circuit board. I think the rear C-S terminal on the sender (far right that I thought was a ground) was tied to the black wire from the body harness and the black wire from the tach was not connected to anything. I changed it to a ground lug but not sure this is right now (?).

MSD box is a #5520 Street Fire box

https://www.amazon.com/photos/all/g...c1-4e1c-b3b7-4b44cf3da6d8&pf_rd_i=13234696011

https://www.amazon.com/photos/all/g...c1-4e1c-b3b7-4b44cf3da6d8&pf_rd_i=13234696011
 
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What is this Tach adapter you mention.
Mine is a 66 and I dont see any adapter in it anywhere.

And for the record my tach is HOPEFULLY optimistic at best.
 
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