In a message dated 12/14/2005 4:22:53 PM Eastern Standard Time,
montyr2157@alltel.net writes:
Lynn,
What is the "hot" set up for MSD. A 6AL box with
two coils on the leading plugs with wasted spark? I plan on using a magneto on
the trailing plugs. What about advance curves? Vacuum advance and the like. I
really don't want to run a distributor for clearance reasons.
Never have run an MSD so I don't know a whole lot
about them.
Monty.
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