7730 and dis

[Gar Willis]

On Wed, 26 May 1999 10:07:20 -0400 (EDT), Pat Ford <pford at qnx.com> wrote:

> I have a dis ( distiruterless ign sys)  off a cavalier and want to know
>how to make the sensor wheel. what I had in mind was a 6" dia 3/8 steel plate
>with 6 slots @ 60 degrees and an extra one @ 10 tdc. how large should the slots
>be?

No matter how large the wheel, the slots should be about the same width as the
metal tip on the Mag sensors, which IIRC correctly are around 1/4" (the metal
tip, that is). That's also the size of the slots in the cast-in metal wheel
that's part of the GM engine cranks.

We use this system on our eXperimental aircraft engines as part of our KIGN
system, and we find that often the built-in linear advance curve in the DIS
module itself is perfectly adequate. If you make the wheel as a flat steel
plate, you might wanna use a configuration John Carroll perfected, and passed
along to us, which I've put up on the FTP site, named:
	PlanarWheel.jpg
which shows the sizing, and some slit/split openings that accentuate the flux
reversals. Shown next to the timing wheel in roughly the correct mounting
position/orientation, is a stock GM mag crank pickup.

BE precise when you machine those semi-holesNslots, cuz even tho there's a PPL
in the module to lock up the slot jitter, the module does NOT like a wheel
that's made sloppy. Best to cut the wheel slots with a rotary table on a milling
machine.

Finally, if you wanna build an ultra-reliable racing IGN system with dual DIS
pickups/coils and waste-fire coil joiners (no single point-of-failure can kill
the IGN system), AND/OR add some fancy programmable advance curves, those
schemes will be available as licenseable PLANS from AirSIG in the
not-too-distant future. Just gotta get EGOR and KEFI out the door, and KIGN will
be next in line.

Gar