Actually, you should NOT seal the module up in anything.
Sealing it up will keep air from circulating around the module and cooling it, and that is a BAD THING.
I turn an old military ammo can up-side-down, mount the module it in with the lid off.
That creates an air bubble around the module when the water gets higher than the dash...
Which it has in my dedicated off roader!
Going back and filling all the connectors with Dielectric Grease will help keep water and corrosion out of your connections,
And using Dielectric Grease in the groove on the under side of the distributor cap before you install it will help make an air bubble inside your distributor cap to keep the distributor from drowning out.
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As for the CDI module upgrade,
I recommend this module for it's price and ease of use.
Summit SUM-850602 - Summit Racing Street & Strip® Multi-Spark Digital CD Ignitions
Since it uses exactly the same terminals as MSD, all the MSD adapters will work with it.
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If you have a '78 to '86 CJ you are upgrading,
This is your starting point...
Summit SUM-850520 - Summit® Ford Duraspark Ignition Adapter Wiring Harnesses
The 'Bell Shaped' connector on the Right with 'Red' & 'White' wires coming out of it is what you plug into your harness, and you connect the CDI module 'Small Red' wire to it.
Unplug the factory module Two Wire connector, and plug this into the factory harness to 'Power Up' the module when you turn the ignition switch on.
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From '78 to '86 CJs all used Jeep/Motorcraft distributors.
This gadget allows you to plug MSD or other CDI modules into the distributor,
MSD Ignition 8869 - MSD Wire Adapters
No wire cutting required, just plug this into the distributor, and the other end has MSD style connector already on it.
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This is a 6 foot 'Extension Cord' for your distributor trigger wires to the CDI module of your choice.
MSD Ignition 8862 - MSD Replacement Cables
This allows me to move the CDI module up to 6 feet from the distributor,
Has the correct connectors at both ends, and is shielded from outside interference so you don't get a bunch of false triggers in your ignition.
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The only other thing you should need is a coil connector.
These can be picked up locally or at the salvage yard.
This is the wiring diagram for 90% of you,
Note there are part numbers for adapters, coil connectors, ect. on the diagram.
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Something you might want to consider,
By taping over the stock coil connector,
The module two wire connector,
And the factory distributor connector,
BUT, Leaving all that in place in the engine bay,
You have a complete BACK UP IGNITION in place in case something happens to the CDI module!
All you do is UNTAPE the module connector and plug it in,
Untape the coil connector and plug it in,
Untape the distributor connector and plug it in,
And you are up and running on the FACTORY IGNITION again!
Trail Redundancy is a WONDERFUL THING when you are 40 miles from the nearest parts store,
Or the ignition takes a
10 minutes after the parts stores close...
Or worse yet,
The ignition quits when you are the
FARTHEST from the parking area or nearest road, and it's a
LONG WALK out!