No distributor is
needed.
The MSD 6T for dirt circle track
service is what we started with, but switched to the 6AL because the rev chip
plugs into the side of the main box, instead of a secondary box with a cannon
plug. The 6T is potted for strength is the other difference.
If the funds are available to have a
4 cylinder Mag on the trailing plugs, then I would rig up a drive for any real
aircraft Mag and grind off two of the points cam lobes and spin the Mag
at crank speed with a little toothed belt. The trailing must be
distributed because one trailing chamber is mixture laden and is exposed to
the plug when the other is firing.
Lost spark on the leading is just
fine. I would trigger the leading MSD from a disc or reluctor on the crank
pulley. I used the pickup from any Chrysler distributor. They are available in
any parts house for about $4.00. I drilled off the rivet heads and flipped the
coil around so the mounting holes are out in the open. I use brass screws from
the hobby shop to replace the rivets, so as not to short out the flux field. If
you rev it up and see the timing retard a bit, just reverse the wires from the
pickup coil. You want to trigger on the flat front of the spike so the reluctor
will be just a hair past dead in front of the reluctor. Easy to set up that way.
If you TIG the magnet side of the
pickup coil to a small steel plate with slotted mounting holes you can move the
timing around a bit and control reluctor clearance.
A crank triggered system is so stable
that you will think the timing light looks like a flashlight shining on a
stopped engine.
There will be two reluctors on the
crank pulley, and one pickup coil to drive the MSD. The MSD output will be
driving a double ended coil, with one coil wire going to each leading plug.
I think MSD has a coil just for this type of installation. Use
only an MSD approved coil, or coils if you want one for each plug. The MSD will
incinerate some of them. The coil primary will be running at 400 volts instead
of 12.
Use inductive coil wire for the run
to the plugs. Don't get near any plugs or plug wire or boots while on or
running. The MSD will fire once when you turn it on. And once when you shut it
off. So the prop may move with surprising authority when the switch is turned
on. So yell clear before touching the switch.
No curves at all. Just 22 to 24
degrees fixed, is fine for up to 9,000 RPM. It will start easy, idle and run
fine at anything between 20 and 27 degrees for a 13B.
Now, think about this. If you have an
old fashioned primer pump, rigged up to inject into the central manifold (in
front of the throttle body). you could loose all of the electric power, and
still come home pumping the primer and running on the Mag.
This is my cooling system for whoever
asked about it.
Lynn E. Hanover
No need to caution me on the plug wires......I am
experienced in that department. Nothing like the sensation of your body spasming
rythmically to the firing of a V8 while feeling as though you are being hit in
the back of the head with a tire iron (repeatedly) while being able to do
absolutely nothing about it. Truly a peculiar sensation I am not eager
to repeat. I was sore all over for a week after that. Still not sure
exactly how I got loose from that damn thing.
Actually I was thinking about using a single
cylinder motor cycle type of magneto directly on the crank for the trailing
plugs. At first I was going to use a snow mobile type (I have a few laying
around) but then I realized you couldn't use waste spark on the trailing
plugs &#%*$!
I would just add another coil and ignition pick up
to the motorcycle unit 180 deg out of phase. If I was really ambitious I could
even add a couple lighting coils and have a (weak) back up to the belt
driven alternator. Probably I am not that ambitious since the battery
gives you some reserve if an alternator fails. If the battery fails you are sol
either way...but the engine keeps running.
reasons for the motorcycle mag:
1) cheap
2) no distribution problems, each plug has it's own
coil and wire.
3.) no high altitude arcing.
4.) cheap
For fuel, I was thinking about using a kinsler
style fuel injection. Should be relatively easy with the rotarys linear power
curve. No falling off on the top end means you don't need a high speed bypass
circuit. Should be able to control the mixture with the barrel valve. Of course
it will not be as precise or automatic as EFI. Should be just as good in cruise
once you get everything dialed in which is where it counts anyway. The big
benefit is I could disconnect the battery and the engine would loose some
rpm, but it would keep running.
Proper shut down procedure (using the fuel
shutoff) should prevent the chance of firing when switching on the ignition
(still should yell clear before touching the switch, if it jumps pilot must wear
a hair shirt for a week for failure to follow shutdown procedure)
Motor arrives tomorrow.
Monty