Home-brewing an ignition advance control

[am018]

I missed the start of this thread  -- I am pretty interested as one of the
ideas I am kicking around at the monent is a knock retard device for classic
50s & 60s cars designed to run on 101 octane fuel what we called 5 star in the
UK    --- basically idea just to put  few degrees spark delay in when knock  is
detected. The first part is a simple stand alone knock detector module. I know
things like this have already been done but as far as I know none is on the
market at the moment.
Andy Macfadyen

Donovan_Dibble at ittauto.com wrote:

> Al,
>
> I've been thinking of making a similar system.  I want (am) going to use a
> PIC 1674 uP for the 'brains'.  This micro has built in A/D for MAP, TPS,
> etc.
> This will hopefully make the system more compact.  Although I haven't
> worked
> on it in a while, I planned on starting by collecting data from a 'regular'
> HEI distributor with vacuum/mechanical advance and simply implementing that
> strategy into the micro.  Later, the knock sensor input and associated
> retard
> logic would be added.  I think the easiest (or most straightforward) way of
> detecting knock will be with external op-amp filters rather than
> calculating
> Fourier Transforms within the micro.  Any signal conditioning would also be
> taken care of with the op-amps.  I got as far as getting the vacuum vs.
> advance data for the HEI but haven't taken it any further.  If you or the
> list
> have any other ideas, I'd like to hear them.  Any motivational ideas would
> be
> welcomed too :)
>
> Don
>
> >I have been pouring over the HEI 4-pin and 7-pin diagrams and info on this
> >page.  The amount of info that is to be found on this page is FANTASTIC!
> I
> >am trying to figure out how to make an ignition advance control for a GM
> HEI.
> >I know MSD sells one but I would like to make my own if possible.  It's a
> lot
> >more satisfying that way and I learn alot more.  Is this done with an
> >adjustable timer IC or is it some other kind of signal conditioning.
> >
> >Any Ideas???
> >
> >Thanks for listening
> >Al Ross