Hi,
I'm rather surprised that you got no response.
In short - the book (Kastner) says 23 degrees of total advance for lower
compression engines, 20 degrees total for motors with high compression. Use
10:1 as the break point... You're at 9.5:1, so figure 23 degrees total.
That being said, get your dizzy recurved for about 15 degrees of advance
(measured at the crank) and set your initial timing to 10 BTDC. That'll
give you a bit more than 23 degrees, but if the motor pings, retard the
dynamic timing at idle a few degrees at a time and then test under load for
pinging.
Now, about that vacuum advance/retard. Most TR6's had a vacuum retard. The
only ones that I know to have had any vacuum advance were early cars, and
they had vac. advance _and_ retard. So these dizzys are easy to identify -
they have two "cans" with vacuum lines on the dizzy body.
That having been said - the dizzy has the capability of mechanical advance.
This is what you should change. Then pull of the advance/retard lines and
lock the "plate" with a screw.
So, find a shop that'll recurve your dizzy and have them fix things for
mechanical advance only. Then plug the vacuum lines on the intake manifold.
Some folks will tell you that Webers don't like vacuum. I actually use the
vac. retard capability on my TR6 and it does seem to work okay, but I'm
sure the setup is sub optimal.
Oh, and the advance should take place between 1500 and 3000 if this is to
be a street car. If it is a racer, you could move the whole curve up to
something like 2000 - 3500... that slope of the curve and the peak advance
are adjustable by changing the springs and the weights inside the dizzy.
Good luck.
rml
TR6's
One with Webahs.
|