crank sensors

[Jonathan R. Lusky]

John S Gwynne writes:
> Micro Switch (made by MG magnets?) makes what looks like a small socket 
> head screw (rather: a screw with a magnet in the end) that could easily be
> placed in the harmonic balancer. I would want to use a horizontal mill 
> to properly locate the holes, but if you hand selected four (V8) equally
> weighted magnets, I would not be concerned with the balance (IMHO). The last
> concern is how strong are they. I have not bought any yet, so I don't know
> for sure if it would handle high revs (the catalog I have doesn't give 
> a spec. for this). I suspect it would.

I like flying magnet approach.  I've used both tooth wheel
(electromotive [puke]), and flying magnets (EFI Technologies) and the
flying magnets win hands down.  You can adapt flying magnets to
anything.  Either put them directly in the crank pulley or balancer,
or mount them in a plate sandwiched somewhere.  Adjust TDC by moving
the sensor.  To mark the compression stroke on cylinder #1, put a single
flying magnet on the cam (or in the distributor).  The timing on the cam
sensor is non-critical, it just tells the controller that the next crank
pulse is TDC on cylinder 1.  The machining involved is really simple,
you could probably do all of it with a drill press and a hacksaw.
Someone could probably come up with some fairly universal hardware.

As far as high RPM goes, we had four 1/8" by 3/4 inch magnets in the
blower drive pulley (4" diameter) on our Kawasaki ZX-6.  The magnets
were a slip fit 3/8" into the pulley, and retained with JB Weld (they
were supposed to have been a press fit, someone screwed up :).  Anyway,
they held 15,000rpm with no problem.

-- 
Jonathan R. Lusky  --  lusky at knuth.mtsu.edu
 "Turbos are nice but I'd rather be blown!"
   89 Jeep Wrangler - 258 / pile of junk!
       80 Toyota Celica - 20R / 5spd