Converting a 71 100hp Johnson to msd ignition

Hi everyone, new to the site. Got a lot of information so far from this site on this issue. I will be using a 6a box. However I have a few questions, The 2 wires coming from the points, the white goes to the white and the does the black just go to a ground? As far as the 2nd coil that just gets grounded out, can I use the original coil to do this instead of buying 2 high vibration coils? Thanks in advance.

Ok, so today I hooked everything up and it won't start. I used 2 coils and grounded 1 out, I did use the original to do this just to see if it would work. Not getting any spark. I had to stop to let the battery charge and I will mess with it again later. I'm thinking of doing just the 1 coil just to see if it fires. I know the msd box and coil are good. Is it possible the dist or points are bad. How do I test that? If anyone out there did this conversion please let me know. I'm trying to sell this boat before the winter and it ran until the day someone came to look at it and of course the pulse pack went again. 1 of many over the years, just want to switch it and be done. Not to mention reliable for selling or if I decide to keep it.

Today I pulled the flywheel looking for any obvious damage. Dist and points looked ok no burnt wires. I am now wondering if the connections were correct from the points, I had the white to white and black to ground. Dont know if i should use the purple and green from the msd instead. Tomorrow I will do a spark test that I got from the msd website to make sure the box is ok. Also I will check for spark coming out of the coil instead of at the plugs.

Ok, I tested the msd box and it checked out ok, I also got spark coming out of the coil. So, I pulled the flywheel again and cleaned the contacts on the rotor and dist. They were gunked up, so I figured that was it, put it all back together and still no spark. Dist had some some small cracks, do you think the dist is faulty, don't have a circuit tester, just test lights. Anything else it could be?

For what it's worth, possible help for you or others, I have no idea. However, I saved this to my database years ago as I thought it interesting.

(Conversion To MSD Ignition)
(By Doug Bryant)

This article was written by Doug Bryant and posted on one of the marine website forums
on Monday, July 23, 2007, at 10:49 PM. Full credit is to go to Doug Bryant. In this case of
publishing the following informmation, I (Joe Reeves) am merely an instrument of transference.

I have had several people email me asking how to convert their old OMC CDI 1 to an MSD Ignition. Here is the instructions on how to do this:

CONVERSION TO MSD IGNITION:

The benefits of running the MSD 6A ignition in place of the factory CDI ignition used in 1967-72 are numerous.
1) The MSD box is more durable. MSD boxes work with as little as 5 volts or as much as 18 volts. Factory box will quit working if charging system is faulty.

2) Factory box sparks one time while MSD ignition box sparks through 20 degrees of crank rotation.

3) MSD box is much cheaper than factory box and MSD box can be purchased from most auto parts stores. Factory boxes are becoming harder to find, as they are no longer in production.

4) An outboard with the MSD box is much easier starting, idles better, and has improved throttle response.

PARTS REQUIRED:

A MSD 6A ignition box and (2) high vibration coils. The coils need to be high vibration, as oil filled will break down from the engine vibrations. The 6A box is currently offered on summitracing.com for $179.00 and the coils are $40 a piece. Total parts cost= $260.00. Cost of a factory box is $250 to $350.

INSTALLATION:

The installation is very straightforward. Follow installation instructions per MSD standard ignition hook up. Heavy red and heavy black wires to 12v positive and 12v ground. Thinner red wire connects to a 12v switched power source. Now here is where this gets a little interesting. The orange and black wires connect to the coil; orange is positive and black negative. However, these wires need to be spliced so that both coils can be hooked up. One coil is connected to the distributor cap and the other coil has its coil wire grounded directly to the block. The reason for this is simple: The MSD ignition produces approximately 45,000 volts. The old system puts out 30,000 volts. The distributor cap will not handle the extra voltage so the 2nd coil is wired in and by grounding it out, the MSD voltage has been cut in half to approximately 22,500 volts. Finally the white wire is connected to the points under the cap. That completes the installation wiring. The MSD box can be mounted directly to the motor or it can be mounted in the boat somewhere. The installer will have to figure out the best locations for both coils to mount as well.

FINAL THOUGHTS:

By upgrading to the MSD system, the motor will perform well for many years to come. The MSD system dramatically improves the overall performance of these motors. The MSD box must be a 6A. MSD offers some less expensive ignition modules but they do not work. The box has to be a true CDI unit. Also, the MSD box will work on any 4, 6, or 8 cylinder 4-stroke engine. However, it will also work on 2 stroke outboards with 4 cylinders and it should also work on 3 cylinder models as well. The author has only used the MSD system on a V4 Johnson 85hp 1970 outboard. It worked great!!

Occasionally the other method of converting these motors to standard 12v inductive ignition is offered as an alternative to the CDI ignition. This conversion is done by adding a condenser and a ballast resistor to the ignition system and using the coil to store up the ignition energy. I have never done this conversion personally but I have been told it would work. However, there is one problem that occurs with this conversion. When this method is used it will directly cause much more wear and tear on the points. This is because when the CDI system is not used more voltage goes through the points, which shortens their lifespan.

These points are no longer available and they are harder and harder to find. So, this should be considered when deciding which conversion to use.

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay auction at:

http://shop.ebay.com/Joe_OMC32/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1

are there any way I can change my 1972 100 hp Johnson sensor base plate to to points base plate,,in other words can I take 1972 85 hp points base plate off and put it on my 1972 100 hp johnson

ok finished mine up today,,i had to take a 1972 85 hp base plate put it on my 1972 100 hp ...mine didn't have points it had a trigger sensor,,,got points now and fire on all fours...got caught in the rain today,,,,start up tomorrow

Got her done,,,,,1972 100 hp johnson changed over to msd,2 blaster coils this son of a gun aint nothing but bad to the bone