Bob:
Because with the vacuum plugged, the timing should be set to 10
BTDC *not* 4 ATDC.
With the vacuum *connected* the timing is 4 ATDC.
The confusion arises because people assume that the TR6 uses a
vacuum advance, when in fact it uses a vacuum RETARD system. So with the
vacuum connected the timing is RETARDED by 14 degrees to 4 ATDC, not
advanced as most people assume.
Another issue is that on most people's cars the vacuum capsule
has long since failed, so even if they get it right and set the timing
to 4 ATDC with the vacuum connected, the car runs like home made dog
food. This is why I tell everyone to DISCONNECT the vacuum, and set the
timing to 10 BTDC, so that even if the vacuum capsule is inoperative,
the timing will be correct.
I say this from personal experience. To use the 4 ATDC number, I
had to replace my vacuum capsule, then the timing works as it should.
Vance
-----Original Message-----
From: 6pack-bounces@autox.team.net [mailto:6pack-bounces@autox.team.net]
On Behalf Of robert fabie
Sent: Friday, October 01, 2010 3:55 PM
To: 6pack@autox.team.net
Subject: [6pack] Simple Question
What is the timing for a '75 with the vacuum plugged idling at approx
850
rpm. How on earth can it be 4 degrees per the specs? It seems to run
best at
about 18 degrees before TDC. I know it's been asked a thousand times
before,
but I hope someone will humor me and just tell me...
Many thanks
Bob
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