MSD Box 6AL Boxes
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Junior Member
Joined: Nov 2017
Posts: 31
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From: Nashville Tn
MSD Box 6AL Boxes
I have some scary wiring on my RX7 with these MSD Boxes. I have two boxes. I am assuming one for leading and one for trailing. I bought the car with it. The car does run but it seems to be running ruff. I know it is getting fuel. So spark is the next part. All grounds have been gone through and fixed. Does anyone have a drawing or a diagram of where the wires should go? What gauge of wire should be used? I believe mine are too thin. I have seen photos of different set ups. Some seem to not use all parts of the Dizzy, others seem to still use all of the Dizzy. What is the best way and why?
This is going on a 12A.
Any and all help would be great!
Thanks
rkegley97
This is going on a 12A.
Any and all help would be great!
Thanks
rkegley97
We need pictures and possibly a drawing that shows the current wiring setup if you can do that. Theres many variations and everyone seems to do it slightly differently.
You have a wasted spark set up.
This means that both of the Leading spark plugs fire at the same time and depending on rotor position in the engine, one of the plugs causes fuel to burn and the other one doesn't cause anything to happen. Hence the term "wasted spark." This is also why the Leading plugs are not attached to the distributor cap. Instead these plugs are connected directly to coils that are connected to one of the MSD boxes. That MSD box will be connected to the Leading Igniter on the distributor.
The other MSD box would be used on the trailing side of the ignition. So it should be connected to the single coil that is wired to the distributor cap and the trailing igniter
You can go here to download instructions from MSD that cover what you have. https://www.msdperformance.com/produ...ing/parts/6430
There are two methods of connection.
The first method is to use the small Red and White wires to connect to the factory ignition. In the case of a Mazda you would be connecting to the out put of the factory igniter(s) so the igniters need to be in good working order. In this arrangement the MSD is only amplifying the current to the coil. This is how your's are connected
The second method uses the magnetic pick up wire harness that comes out of the other end of the MSD box. This setup eliminates the Mazda igniter. The trick is to create a connection at the distributor to so that the MSD can be connected to the just the pickup inside the distributor. There are threads that explain how to do this on this Forum.
Recommendations:
Move the MDS from the exhaust side of the engine compartment. They don't like to get hot.
There is little value in using an MSD on the trailing side of the ignition. I would let the stock Mazda ignition handle that. If you do this, you will end up with a spare MSD!
From the pictures the wire sizes going to the coils look fine. The big power and ground wires need to be big. I use 10ga on my car for these connections. The big red wire should attach to the positive side of the battery and the big black needs to go to a good ground.
Check the coils, wires, etc for resistance that is in spec.
Ignition timing adjustment is per factory instructions with what this ignition.
.
This means that both of the Leading spark plugs fire at the same time and depending on rotor position in the engine, one of the plugs causes fuel to burn and the other one doesn't cause anything to happen. Hence the term "wasted spark." This is also why the Leading plugs are not attached to the distributor cap. Instead these plugs are connected directly to coils that are connected to one of the MSD boxes. That MSD box will be connected to the Leading Igniter on the distributor.
The other MSD box would be used on the trailing side of the ignition. So it should be connected to the single coil that is wired to the distributor cap and the trailing igniter
You can go here to download instructions from MSD that cover what you have. https://www.msdperformance.com/produ...ing/parts/6430
There are two methods of connection.
The first method is to use the small Red and White wires to connect to the factory ignition. In the case of a Mazda you would be connecting to the out put of the factory igniter(s) so the igniters need to be in good working order. In this arrangement the MSD is only amplifying the current to the coil. This is how your's are connected
The second method uses the magnetic pick up wire harness that comes out of the other end of the MSD box. This setup eliminates the Mazda igniter. The trick is to create a connection at the distributor to so that the MSD can be connected to the just the pickup inside the distributor. There are threads that explain how to do this on this Forum.
Recommendations:
Move the MDS from the exhaust side of the engine compartment. They don't like to get hot.
There is little value in using an MSD on the trailing side of the ignition. I would let the stock Mazda ignition handle that. If you do this, you will end up with a spare MSD!
From the pictures the wire sizes going to the coils look fine. The big power and ground wires need to be big. I use 10ga on my car for these connections. The big red wire should attach to the positive side of the battery and the big black needs to go to a good ground.
Check the coils, wires, etc for resistance that is in spec.
Ignition timing adjustment is per factory instructions with what this ignition.
.
Thread Starter
Junior Member
Joined: Nov 2017
Posts: 31
Likes: 0
From: Nashville Tn
You have a wasted spark set up.
This means that both of the Leading spark plugs fire at the same time and depending on rotor position in the engine, one of the plugs causes fuel to burn and the other one doesn't cause anything to happen. Hence the term "wasted spark." This is also why the Leading plugs are not attached to the distributor cap. Instead these plugs are connected directly to coils that are connected to one of the MSD boxes. That MSD box will be connected to the Leading Igniter on the distributor.
The other MSD box would be used on the trailing side of the ignition. So it should be connected to the single coil that is wired to the distributor cap and the trailing igniter
You can go here to download instructions from MSD that cover what you have. https://www.msdperformance.com/produ...ing/parts/6430
There are two methods of connection.
The first method is to use the small Red and White wires to connect to the factory ignition. In the case of a Mazda you would be connecting to the out put of the factory igniter(s) so the igniters need to be in good working order. In this arrangement the MSD is only amplifying the current to the coil. This is how your's are connected
The second method uses the magnetic pick up wire harness that comes out of the other end of the MSD box. This setup eliminates the Mazda igniter. The trick is to create a connection at the distributor to so that the MSD can be connected to the just the pickup inside the distributor. There are threads that explain how to do this on this Forum.
Recommendations:
Move the MDS from the exhaust side of the engine compartment. They don't like to get hot.
There is little value in using an MSD on the trailing side of the ignition. I would let the stock Mazda ignition handle that. If you do this, you will end up with a spare MSD!
From the pictures the wire sizes going to the coils look fine. The big power and ground wires need to be big. I use 10ga on my car for these connections. The big red wire should attach to the positive side of the battery and the big black needs to go to a good ground.
Check the coils, wires, etc for resistance that is in spec.
Ignition timing adjustment is per factory instructions with what this ignition.
.
This means that both of the Leading spark plugs fire at the same time and depending on rotor position in the engine, one of the plugs causes fuel to burn and the other one doesn't cause anything to happen. Hence the term "wasted spark." This is also why the Leading plugs are not attached to the distributor cap. Instead these plugs are connected directly to coils that are connected to one of the MSD boxes. That MSD box will be connected to the Leading Igniter on the distributor.
The other MSD box would be used on the trailing side of the ignition. So it should be connected to the single coil that is wired to the distributor cap and the trailing igniter
You can go here to download instructions from MSD that cover what you have. https://www.msdperformance.com/produ...ing/parts/6430
There are two methods of connection.
The first method is to use the small Red and White wires to connect to the factory ignition. In the case of a Mazda you would be connecting to the out put of the factory igniter(s) so the igniters need to be in good working order. In this arrangement the MSD is only amplifying the current to the coil. This is how your's are connected
The second method uses the magnetic pick up wire harness that comes out of the other end of the MSD box. This setup eliminates the Mazda igniter. The trick is to create a connection at the distributor to so that the MSD can be connected to the just the pickup inside the distributor. There are threads that explain how to do this on this Forum.
Recommendations:
Move the MDS from the exhaust side of the engine compartment. They don't like to get hot.
There is little value in using an MSD on the trailing side of the ignition. I would let the stock Mazda ignition handle that. If you do this, you will end up with a spare MSD!
From the pictures the wire sizes going to the coils look fine. The big power and ground wires need to be big. I use 10ga on my car for these connections. The big red wire should attach to the positive side of the battery and the big black needs to go to a good ground.
Check the coils, wires, etc for resistance that is in spec.
Ignition timing adjustment is per factory instructions with what this ignition.
.
As you can tell, when it comes to ignition understanding, I do not really understand it was well as I probably should. This is my first Rotary car and the placement of trailing and leading seem to just baffle my mind. Last car I worked on with ignition was a C10. Any more light to bring to the table of what you think is the best form of action?
I don't think you need the MSD for the trailing side of the ignition. The factory ignition is fine.
Keeping the MSD on the Leading side:
Running the Leading side through the distributor means that you only need one coil so it saves money/maintenance.
Running wasted spark on the leading side (what you have now) is better for high RPM because it eliminates the potential for arching in the distrib cap which can create miss-fires. I run wasted spark on my race car and have for years. Mind you my race car spends most of it's time between 5.5K and 8.5K when I am driving it.
Removing the MSD boxes:
Eliminates the variable of the MSD boxes which can go bad/fail over time. The OE ignition is generally fine for a stockish street car.
Keeping the MSD on the Leading side:
Running the Leading side through the distributor means that you only need one coil so it saves money/maintenance.
Running wasted spark on the leading side (what you have now) is better for high RPM because it eliminates the potential for arching in the distrib cap which can create miss-fires. I run wasted spark on my race car and have for years. Mind you my race car spends most of it's time between 5.5K and 8.5K when I am driving it.
Removing the MSD boxes:
Eliminates the variable of the MSD boxes which can go bad/fail over time. The OE ignition is generally fine for a stockish street car.