Trouble is it doesn't allow for different pinging limits at different rpms,
temps, centrifugal advance and vacuum advance - 'under load' is not enough.
The whole reason distributors have centrifugal and vacuum advance mechanisms
is to attempt to run with maximum advance under all conditions and hence get
the best economy when cruising and the best performance under power.
However as mechanical devices they are very crude which is one of the
reasons a modern ignition system can get so much more out of the same
engine. But then again, manufacturers specs are always conservative, so
pretty-well all of us should be able to run at something higher than the
manufacturers specs, I would have thought. The only thing your mechanic
friend seems to have missed out is "Then measure the timing and write it
down".
My (very old) vacuum gauge instructions stated to advance the timing until
the needle flicks (much more sensitive than audible pinking) then back it
off 3/4 of an inch Hg. Many years later I tried this on my roadster and
came out at barely more than spec. So I didn't bother again. I discussed
this method with a racer who's site gives info on setting mixture with a
vacuum gauge and he was very rude about it.
PaulH.
----- Original Message -----
From: Charles Sorkin <cdsorkin@ix.netcom.com>
To: MGs List <mgs@autox.team.net>
Sent: Saturday, September 30, 2000 2:43 PM
Subject: How's this for a timing method?
> A mechanic friend recently suggested the following method for setting
timing
> on an older engine such as the A-series:
>
> 1. Let the gas tank get near empty, then add a gallon or so of an economy
> grade fuel.
> 2. Set the timing as far advanced as it will go until it starts pinging
> while under load.
> 3. Then fill the tank up with premium fuel.
>
> He claims that with a high octane fuel, it won't ping as early, and thus
> should provide peppy performance.
>
> I regarded this with skepticism, of course, but this fellow has been a
> mechanic for many years, and has set up more than a few racing engines.
Is
> this a reasonable method? Or will I still be "detonating" the mixture?
>
> Regards,
>
> Charles
> '74 Midget
> '68 Sprite
> Bloomfield, NJ
> cdsorkin@ix.netcom.com
> "How about we duck inside for a Hen?"
>
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