Optimising ignition timing

[graham.hilder@telecom.co.nz (Graham Hilder)]

Thanks to Rich and to Thomas for their replies to my query, both advising
that the empirical method for setting your ignition timing (advance until just
before it knocks) is OK.

This raises a couple of follow-up queries though ......

1.  Rich warned to be very careful to avoid ANY knocking, and hence to
do the test under the most provocative conditions (lowest expected 
octane fuel, high external and internal temps, and driving up hill with
engine loaded a bit more than normal by keeping revs low).   And then to 
add a safety margin by backing off about two degrees after finding the
detonation point.  And to be really careful that you actually can hear any
slight knocking which might be occurring.

My query......  I  understand all these points and agree totally, but if I just
set my timing up to the factory marks and forget it, then I'm not worrying
about all these things and doing any of those tests, so is there a good
chance that in fact the engine might be knocking slightly in some
conditions?  (without me hearing it...... Alfettas for example are not the
queitest cars in the world).
In other words, should one really be doing the above sorts of careful
checks even after using the factory marks?  How conservative are
those marks?  I know I can hear the engine knock when it's bad
enough..... after a bad shipment of fuel for example..... but if it's just the
merest case of knocking I probably wouldn't hear it unless I went looking
for it carefully as per the above testing procedure.


2.   The second query is...... Rich and Thomas only commented on the
ADVANCE UNTIL JUST BEFORE IT KNOCKS method.
What about the other empirical method I've often heard suggested..... i.e.
set the timing to that which gives best acceleration in a high gear from a
mid range to a high range rev point.
How come no comment.....is this method not known or not preferred?
It seems to me that maybe this could be a better method. If it is true that
any knocking would degrade the engine's output (is this true?), then if
your timing setting is giving you your best acceleration-time then you
could be assured that no knocking was occurring. Sounds good to
me...... is it correct though?    Of course the timed-acceleration test
would need to be done under knock-provoking conditions as above. 

Any comments please ?
Thanks again everyone,
Graham H.,  NZ.
71 & 77 Nords, 82 & 83 Suds.