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