Flywheel/Encoder patterns

[Kalle Pihlajasaari]

Hi Snake,

> >>An encoder giving absolute crank position would implicitly supply an
> >>interrupt when the position changes value. Reading crank position directly 
> 
> >>means you wouldn't have to fool with timers or counters to derive it. 
> You'd
> >>also know exactly what the position is upon start-up without having to 
> store
> >>the last known position info upon shutdown. No way around the cam sensor 
> tho
> >>that I can see.
> >
> >Why not just have an encoder or sensor on the cam if you can get enough
> >resolution?
> 
> Kalle has a good idea -- some sort of retrofit device in a distributor 
> housing that encodes off the cam. This would work great *IF* you could get 
> rid of all the mechanical slop between the crank and the encoder, like 
> timing-chain stretch and cam/distributor gear backlash.

I was thinking for 'no-brainer' retro applications one could just add
a viscous brake to te shaft so after the first 20 degrees the units would
then be at the extreme limit of the backlash.

Problem is extra wear on components from the drag and getting something
that will work at all engine speeds, perhaps something electromagnetic
like a Tacho generator (plug it into your Tacho display also)

You would have to go with multiple coils to keep things simple but
might be able to keep the old dizzy in the boot (trunk).  Getting
this to work with the fuel system would take some doing but if
you make your own into the existing harness you could swap the old
unit back again using the old 35 tooth sensor if you get stuck in
vancouver or something.

Cheers     *<<<-|
-- 
Kalle Pihlajasaari   kalle at ip.co.za   http://www.ip.co.za/ip
Interface Products   P O Box 15775, DOORNFONTEIN, 2028, South Africa
+ 27 (11) 402-7750   Fax: 402-7751    http://www.ip.co.za/people/kalle