I think you need the advance connected. Its the retard (if existing) that
can be disconnected. 8 to 10 BTDC is right without the retard disconnected,
runs good here with 93 R+M/2 (about 98 RON). Loosely speaking, the engine
needs to advance as it revs because the time it takes gasoline to explode
stays roughly the same but the motion of the engine is going faster and
faster. The spark needs to occur the same period of time before the maximum
explosion point, which is earlier and earlier in terms of degrees before top
dead center as the engine speeds up.
There was some interesting discussion of this a few months back. Some of it
might be posted in the VTR's maintenance section of their web site.
http://www.vyr.org
Good luck.
Jim Altman jaltman@altlaw.com Illigitimi non Carborundum
http://www.altlaw.com/metro/jaltman.html 69-TR6#CC28754L W4UCK
-----Original Message-----
From: owner-triumphs@autox.team.net
[mailto:owner-triumphs@autox.team.net]On Behalf Of Bob Hutton
Sent: Monday, December 07, 1998 5:29 PM
To: triumphs@autox. team. net
Subject: Knock sensors and vacuum retard distributors (LONG)
List,
Has anyone any thoughts on the possibility of using a 'knock sensor' in
conjunction with a vacuum retard distributor? How, I don't know yet.
The reason I ask is that my 2500TC sedan has a compression of 180 to 190 PSI
and doesn't like the relatively low octane fuel here in Australia. I was
running on 94RON leaded (super)on 4 degrees BTDC with the vacuum advance
disconnected to eliminate knocking.
On the weekend I switched over to 97RON 'premium unleaded' and retimed it to
8 degrees BTDC, still no vacuum advance. It ran much smoother, quieter
exhaust at idle, but knocked badly on acceleration. It's now retimed to 5
degrees BTDC with no vacuum advance and no knock.
It occurred to me that it would be nice to have a distributorless ignition
with a knock sensor to retard it as needed, but that seems too difficult.
Hence, my question above.
Any thoughts?
Regards,
Bob Hutton
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