MSD Tach Output Wire
12-29-2011, 02:55 PM
#1
Rennlist Member
Thread Starter
MSD Tach Output Wire
I'm getting ready to install an MSD 6A ignition. I've got most of the wiring figured out, i.e., hooking into the "green wire", the coil connections, etc. I have read RicerSchnitzzle's and SMTCapeCod's posts on the subject.
So the remaining point I need clarification on is the MSD Tach output wire. Where does it connect to? Or is it needed? From what I have read, the MSD tach adapter is not required. Is this because the MSD is "spliced" into the green wire without disconnecting from the OEM? I've tried to frame the problem in two ways, here:
Scenario 1: It would seem that if I spliced directly into the green wire leaving it still hooked to the OEM ingnition controller, then the MSD tach wire is probably not needed. I've got some leftover AMP connectors, so not a problem.
Scenario 2: Disconnect the green wire from OEM controller and re-connect only into MSD. If this approach, is the MSD Tach output wire then needed to run dash tach?
Any thoughts or direction would be most appreciated.
So the remaining point I need clarification on is the MSD Tach output wire. Where does it connect to? Or is it needed? From what I have read, the MSD tach adapter is not required. Is this because the MSD is "spliced" into the green wire without disconnecting from the OEM? I've tried to frame the problem in two ways, here:
Scenario 1: It would seem that if I spliced directly into the green wire leaving it still hooked to the OEM ingnition controller, then the MSD tach wire is probably not needed. I've got some leftover AMP connectors, so not a problem.
Scenario 2: Disconnect the green wire from OEM controller and re-connect only into MSD. If this approach, is the MSD Tach output wire then needed to run dash tach?
Any thoughts or direction would be most appreciated.
12-29-2011, 03:20 PM
#3
Race Car
OK, took a deep breath and dove deeper into PM files. Scary in there. Here is some amplifying info from an exchange between Ricerschnitzzle formerly TerraPistris I think, and myself...:
-----------------------
Yes. Thanks, you were a big help. It was actually very easy. Black to ground, red to positive jumper post, white to old positive coil wire, black to old negative coil wire. I changed the coil hook ups to spade connectors. I then put spade connectors on the ends of the old coil wires as well as the ends of the new coil wires. I can disconnect 2 wires and go right back to stock ignition in seconds. Keeps the Tac working off the old ignition box so no adaptor needed. Zip tied the MSD to the strut brace. Soldered in a piece of brass over the resistor in the rotor and all is well. Plugs gapped at .50 so far and works well. Haven't had a chance to go with the nitrous yet, since my starter went out the day I got the MSD in!!! I'm thinking it's the starter selenoid. It bump starts fine. When the starter is off the car it engages and spins the bendix fine. On the car it tries to engage and binds. Thinking the started selenoid is not getting enough power to throw the bendix into the flywheel.
Just started vacation today so I have all week to figure it out. Unfortunately I was supposed to head out to SITM last night..
Thanks again for the help and follow up! let me know how to repay the favor sometime.
Mike
--------------------------------------------------
Anyway..my recollection is a little weak. There is one tech at MSD that is capable of talking through the process based on prior 928 installs....but do NOT heed his advise that the tack conversion module is required. Mine was whacked with the unit, read well without it. Flush fifty bucks.
Other than that....the green distributor wire constitutes TWO feeds to the MSD. The outer shielding is one, and the inner core is the other. If I remember correctly, the outer shielding is (+pos) and the inner (-neg). I’m bad with the electronics, but this baffled me because I assumed the + signal could induce a signal in the -...but, again IIRC, that’s the way it was.
In the end it was a three wire hook up, after I sacrificed an older green distributor lead. The car is at a different address, so I would need to check on specifics. I did post to the "Modifications" portion of Rennlist at the time, and also to MSD's forum.
ONe key thing to remember - as far as I can tell ALL 928 rotors had an internal resistor molded in. I was running a hotter MSD coil, but I bet that even the multiple sparks will toast it. I soldered in a brass conductor to replace the resistor and then sealed it.
---------------------------------------------------------------------
Quote:
Originally Posted by Terra-pistris
Greetings!
I have been sitting on my MSD 6AL for a few months now and have not gotten the time to install yet. I see you are running the same set up. Any words of wisdom? I have an '81 Euro 5 speed. I have the MSD HVC coil as well. I plan on adding the retard control, however have read folks have troubles with the 928.
Forgive my ignorance with the following questions...I was a muscle car geek for years. Ignition systems are greek (or german) to me.
The distributor has only one lead coming off. I assume it is the trigger for the current system as well as tach info. If I tap into it for the MSD trigger will I maintain my tach? Can I then remove the old Bosch ignition with out loosing the tach signal?
I've been running N20 with no retard, which mean running the timing lower all the time, even when not hit the giggle gas... Hoping the MSD and retard switch will help.
Thanks for your time!
Mike
-----------
Additional important info re: Coils https://rennlist.com/forums/256470-post9.html
Additional corroboration re: rotor http://www.msdignition.com/forum/showthread.php?t=3028
-----------------------
Yes. Thanks, you were a big help. It was actually very easy. Black to ground, red to positive jumper post, white to old positive coil wire, black to old negative coil wire. I changed the coil hook ups to spade connectors. I then put spade connectors on the ends of the old coil wires as well as the ends of the new coil wires. I can disconnect 2 wires and go right back to stock ignition in seconds. Keeps the Tac working off the old ignition box so no adaptor needed. Zip tied the MSD to the strut brace. Soldered in a piece of brass over the resistor in the rotor and all is well. Plugs gapped at .50 so far and works well. Haven't had a chance to go with the nitrous yet, since my starter went out the day I got the MSD in!!! I'm thinking it's the starter selenoid. It bump starts fine. When the starter is off the car it engages and spins the bendix fine. On the car it tries to engage and binds. Thinking the started selenoid is not getting enough power to throw the bendix into the flywheel.
Just started vacation today so I have all week to figure it out. Unfortunately I was supposed to head out to SITM last night..
Thanks again for the help and follow up! let me know how to repay the favor sometime.
Mike
--------------------------------------------------
Anyway..my recollection is a little weak. There is one tech at MSD that is capable of talking through the process based on prior 928 installs....but do NOT heed his advise that the tack conversion module is required. Mine was whacked with the unit, read well without it. Flush fifty bucks.
Other than that....the green distributor wire constitutes TWO feeds to the MSD. The outer shielding is one, and the inner core is the other. If I remember correctly, the outer shielding is (+pos) and the inner (-neg). I’m bad with the electronics, but this baffled me because I assumed the + signal could induce a signal in the -...but, again IIRC, that’s the way it was.
In the end it was a three wire hook up, after I sacrificed an older green distributor lead. The car is at a different address, so I would need to check on specifics. I did post to the "Modifications" portion of Rennlist at the time, and also to MSD's forum.
ONe key thing to remember - as far as I can tell ALL 928 rotors had an internal resistor molded in. I was running a hotter MSD coil, but I bet that even the multiple sparks will toast it. I soldered in a brass conductor to replace the resistor and then sealed it.
---------------------------------------------------------------------
Quote:
Originally Posted by Terra-pistris
Greetings!
I have been sitting on my MSD 6AL for a few months now and have not gotten the time to install yet. I see you are running the same set up. Any words of wisdom? I have an '81 Euro 5 speed. I have the MSD HVC coil as well. I plan on adding the retard control, however have read folks have troubles with the 928.
Forgive my ignorance with the following questions...I was a muscle car geek for years. Ignition systems are greek (or german) to me.
The distributor has only one lead coming off. I assume it is the trigger for the current system as well as tach info. If I tap into it for the MSD trigger will I maintain my tach? Can I then remove the old Bosch ignition with out loosing the tach signal?
I've been running N20 with no retard, which mean running the timing lower all the time, even when not hit the giggle gas... Hoping the MSD and retard switch will help.
Thanks for your time!
Mike
-----------
Additional important info re: Coils https://rennlist.com/forums/256470-post9.html
Additional corroboration re: rotor http://www.msdignition.com/forum/showthread.php?t=3028
Last edited by SMTCapeCod; 12-29-2011 at 03:37 PM.
12-29-2011, 03:24 PM
#4
Rennlist Member
Thread Starter
No worries. Did you just splice into the green wire, or connect directly, i.e., disconnect completely from the OEM CD? I remember a lot of discussion about the splicing, etc. - wasn't sure what that exactly meant.
12-29-2011, 03:33 PM
#5
Race Car
I'll need to find a schematic somwhere to refresh my memory. WSM are with car.
I believe that I used an older/suspect green wire, split it, and routed directly to the MSD, then connected mSD harness to the terminals in the factory connector. So, removed the box entirely- it was faulty which is what started this adventure.
https://rennlist.com/forums/3075902-post39.html
I believe that I used an older/suspect green wire, split it, and routed directly to the MSD, then connected mSD harness to the terminals in the factory connector. So, removed the box entirely- it was faulty which is what started this adventure.
https://rennlist.com/forums/3075902-post39.html
12-29-2011, 04:10 PM
#6
Rennlist Member
Thread Starter
I forgot that you no longer had OEM CDI box, so you fit scenario 2. So probably have to use the MSD tach output wire, otherwise wouldn't know how the dash tach would get signal.
Also, I forgot about the resistor in the rotor. I am already using the MSD Blaster coil. Maybe I'll just buy a new rotor for backup while I modify the existing one.
Also, I forgot about the resistor in the rotor. I am already using the MSD Blaster coil. Maybe I'll just buy a new rotor for backup while I modify the existing one.
01-02-2012, 07:16 PM
#7
Rennlist Member
Thread Starter
UPDATE: I figured out the tach wire hookup. Was perhaps too obvious - small green wire labeled 16 on the original ignition box master plug.
However, I can't make the MSD fire a spark. Tried hooking it two different ways - with and without the green coax from the distributor according to the two approaches chronicled by SMTCapeCod and RicerSchnitzzle. BTW, these match the two basic plans outlined in the MSD manual.
I've rechecked the wiring several times; I've got a solid red led light on the MSD unit (so assumes it means the power is ok); and I have disconnected the MSD unit a couple of times to see if the old system works - it fires right up everytime. Any ideas or experience with the MSD unit or troubleshooting diagnostics? Anything would be most appreciated.
However, I can't make the MSD fire a spark. Tried hooking it two different ways - with and without the green coax from the distributor according to the two approaches chronicled by SMTCapeCod and RicerSchnitzzle. BTW, these match the two basic plans outlined in the MSD manual.
I've rechecked the wiring several times; I've got a solid red led light on the MSD unit (so assumes it means the power is ok); and I have disconnected the MSD unit a couple of times to see if the old system works - it fires right up everytime. Any ideas or experience with the MSD unit or troubleshooting diagnostics? Anything would be most appreciated.
