DUAL IGNITIONS FOR TRAIL REDUNDANCY
If It Happens On The Trail,
You Had Better Be Ready For It...
Mr. Murphy (Murphy's Law) Visits Me On A Regular Basis, So I Try And Be Ready
For Him.
READ THIS FIRST...
FIRST OFF...
Here is a shot of the points plate with dual Chrysler triggers.
Here is the breaker points advance plate with dual mag triggers installed in the distributor.
Although a stock cap and rotor will still work, I'm not one to leave things alone.
The black collar is a 'Cap-Adapt' from MSD ignitions.
With The Distributor Ready To Run, It's Time For Wiring & Ignition Modules...
Let me say, I'm not tryin to sell this as a home game!
This is Over Kill by any reasonable yardstick, but I believe in 'Self Rescue'.
This is just what one man (me) has done to try and update a very old vehicle.
If you are not VERY comfortable with the theroy of how a distributor works, THEN BY ALL MEANS,
DON'T ATTEMPT THIS PROJECT!!!
A quick recap,
Starting with a Delco breaker points distributor in a '73 CJ-5 With factory 304 CID V-8.
Converting that distributor to use a Chrysler type Reluctor and Magnetic Trigger.
For Ignition potential testing and for trail redundancy, Converting the distributor to dual
Magnetic Triggers.
Click for larger image.
That's a stray V-8 Chrysler reluctor in between the mag triggers
Notice there is plenty of room for dual triggers on the stock Delco points mounting plate.
Click for larger image.
Install of the reluctor on the advance head was covered in the previous page.
A second hole had to be drilled in the distributor housing for the second set of pickup wires
to exit.
This is the only modificaiton to the housing or any other parts of the distributor except for
the vacuum advance plate where the mag triggers were located.
Click for larger image.
This is a 'Phased Rotor' from MSD, and it allows me to phase in the rotor to the center of the
terminals when that terminal is being fired.
Notice the slots on the top half of the rotor? These let me move just the rotor nose where I
want it.
Notice the rotor nose is held in place by a screw. This allows for rebuilding the rotor, saving
the cost of a new rotor each time I tune up.
Click for larger image.
This adaptor allows me to use the large style Ford Distributor cap that is far superior to the
stock type Delco cap.
This adaptor system is a one time purchase because it doesn't wear out.
Click for larger image.
This is the cap adaptor with the large Ford Distributor cap installed.
The large cap has a number of advantages...
Larger diameter moves terminals farther apart, 'Tower' type terminals, Distributor venting,
Interior design that inhibits crossfire, Low resistance center 'button', and the list goes on.
See Ignition Basics for a full list of featuers.
Click for larger image.
Here is the completed distributor ready for install.
Notice the new distributor gasket hanging from a terminal? Always a good idea!
The black thing on top is a plug wire hold down.
Notice that new shiny adjustable vacuum advance? Good idea to throw one on when you have
everything else torn down.
Click for larger image.
Here is a shot of the plug wire spider, and you'll notice the hole in the distributor cap.
This is the test cap I use for rotor phasing, one of the last steps in setting up a distributor.
With a timing light, this cap allows me to actually see where the rotor nose is when advance
comes into play.
With the aluminum terminals, this cap is not much good for anything else but cutting up...
Click for larger image.
These are the E-core coils from a Ford TFI ignition and the material I'm going to use as a
bracket and heat sink for the GM HEI module.
I could have used MSD coils or GM External HEI coils. The Ford E-core coils were the best for
economy, and for module testing I needed everything else to be equal.
There is no bracket to mount dual coils in, and the GM HEI module MUST have a heat sink to
live, and the bracket will afford the module quite a bit of protection from trail debris.
Aluminum is an excelent heat sink so the bracket will do double duty.
Since I'm using this vehicle as a test bed to compair the DuraSpark module to the GM HEI module,
I need both wiring diagrams.
Here is a Ford DuraSpark Ignition Module Wiring Diagram.
The advantage of the Ford DuraSpark module is Jeep used Motorcraft (Ford) ignitions in
everthing from '78 to '90, so replacment modules are easy to come by and finding someone on the
trail with a back up module is usually pretty easy.
All DuraSpark modules will interchange (there is a DuraSpark II ignition, but we aren't going
there...).
The drawback to this ignition system is some of the factory connectors are virtually impossible
to find in the aftermarket new...
There are places to buy new harnesses for Ford Applications, but they won't be a "Drop In" for
a Jeep application.
And here is the GM HEI wiring diagram...
Using the GM HEI module is a good idea when you are trying to retro-fit one of the '74 to '77
Jeeps with the Prestolite ignition, or upgrading the '73 and older Jeeps from points to
electronic ignition.
In a '78 through '90 Jeep that came with a Motorcraft distributor and DuraSpark module it's not
really a viable swap, although some people swear by it.
That is one of the reasons why this dual rig was built.
To test the weaknesses and strong points of each, and maybe lay some myths to rest...