Hitachi/MI

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Hitachi/MI

 

After interaction with several people from the Airsoob mailing list, I was suggested to try some Mitsubishi integrated pickup/ignition modules.  I found those modules in Hyundai Excel 1988 cars.  I worked closely with Paul Messinger to evaluate that setup and while the modules are installable inside a Subaru Hitachi distributor, it remains to be determined if this will be a suitable setup.  Paul found that the performance of the module diminishes as rpm increase above 4000 rpm... but perhaps not enough to affect operation. In fact, I tested a dizzy on a workbench (attached to the press drill) at the equivalent of 5300 engine rpm (2640 dizzy rpm) and it worked very well, showing good sparks.  

Continuing on this experiment, Paul made a few conversion kits for me so I convert one of my Hitachi distributors.

One thing that impresses me about this MI distributor is that it does not requires any rotational speed to initiate a spark.  The pickup works like a switch that triggers when the side of the reluctor leg comes near the center of the sensor.  I did an initial test on the aircraft, but then, I decided to make a little test bench so I could get assured I get working units when I go to the scrap yard for more distributors.

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This is Paul's conversion kit.  He supplies everything we need except the dizzy and the control modules.  In the kit, we have the mounting plate, vacuum port plug, bushings, screws, connectors, shrink wrap, wires, wire jacket (silicon/fiber), heat sink compound, Loctite and some preliminary instructions.  Notice that the wires supplied are 20awg two conductors shielded wire.  I decided to use 16awg that I had on hand instead.  The o-ring supplied in the kit is bigger than the one I got from my local Subaru dealer.  I decided to use the o-ring I got from Subaru. 

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So, I disassembled and cleaned my Hitachi distributor in August 2003.

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And then, in December, I took a few hours to continue..!  I am pursuing a full-time MBA program and I found it to drain a lot more energy than I anticipated.  I did not touch anything on the aircraft between August (when I started that MBA) and the holiday season.

So, I lubricated and reassembled the mechanical part of the distributor and prepared the electronic components.  Notice the small bushings supplied in the kit (I ended up making closer tolerance bushings when looking for a timing difference solution between the two modules).  These bushings are installed in one of the screw hole for each module to restrain the play and ease position-adjustment of the module.  Then, I applied the heat sink compound and installed the modules on the plate.  To have proper clearance between the bottom of the reluctor and the control module, I installed it on the reverse side (protruding legs facing upward instead of downward.  I don't think this will affect operation as the reluctor is symmetrical.

Oh, one important and significant thing I was about to forget... we need to use the Mitsubishi reluctor and to do this, it is required to reduce the diameter of the Hitachi distributor shaft by about .002" (just where the reluctor sits).  I did this on a friend's lathe.   And to compensate for the smaller thickness of the Mitsubishi reluctor, I made a 0.40" washer using aluminum that I installed on top of the reluctor.

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According with one of my Haynes manuals, the air gap should be 0.030".   I adjusted the position of the plate so what when the rotor blade covers contact for cylinder no 1, the reluctor tip is just at the center of the pickup sensor.  Notice that this setup is made so that the rotor blade will be properly positioned at any position of the mechanical advance mechanism. I installed the spacing washer between the reluctor and rotor. 

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When looking for how to run the wiring, I decided to have them come out of the vacuum advance port.  So I drilled a 5/16" hole in the port plug supplied in Paul's kit to accommodate the cable (composed of two 16awg dual conductor shielded wires and the silicon/fiber jacket).  I had to redo the shink wrap (yellow) because it needed to be very compact to fit in the tight space available. 

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I soldered the connectors supplied in the kit and I reused the connector covers from the Mitsubishi distributors.  Then, I tested that both modules work fine on my little test bench.  Every spark plug fires properly in sequence!  So, there it is!!  It is ready for installation and further testing.

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The Mitsubishi pickup can be purchased from NAPA... it is the TP160.

Normally, it is used with a canister coil (IC12) and an 1.4ohm ballast resistor (ICR34).  However, there are a few installations with an e-core potted coil (IC105 and IC108 - the 105 seems to be electrically similar to the 107 and I did not check for the IC108):

 

Mitsubishi Pickup truck 1987-1989  use the IC108 coil

Mitsubishi Gallant 1986 use the IC105 coil

Dodge Power Ram 50 and Ram 50 1987-1989 use the IC108 coil

Since the auto parts catalogs don't show a ballast resistor when using the potted coil, I tried without it; I burned two IC107 coils.  I got a printout of a Dodge RAM 50 1988 pickup truck and saw that there is indeed a resistor in the circuit, but I don't know which one.

April 25, 04: I ended up using the Nippodenso/HEI system but I believe that the MI system is also a good one (few connections, integrated pickup/igniter, etc).

 

 

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