Brian,
I have run the Twin Cam MGA engine for many years with a locked distibutor,
and back when SVRA allowed them, a Crank Fire with fixed advance.
Works just fine, starts from cold, even in the Fall and Spring (Webers), and
idles as well as can be expected, about the same as with variable timing. It
also hot starts, as long as you dont poke at the accelerator pumps too much
Timing is fixed at between 34 and 36 degrees.. somehow each new engine wants a
slightly different # as defined by the dyno runs.
Since the Twin Cam, even with a factory advance curve had all its advance in
by 4000 RPM or so, and since I'm never under 5500 on the track (at least not
deliberately), the fixed timing has only one effect I have noticed.. and its a
benefit.
If you use a fast rise, low persistency timing light you can get a good view
of the spark scatter that a Lucas unit gives. By removing a bunch of rather
imprecise bits, the scatter is reduced and we always felt performance was
enhanced in a minor way.
Just to put this in context, this is a high output Comptune engine, which
produces almost 100 HP/litre at 7250 RPM.
Tony Simms
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