<VV> turbo distrubutor

[Jim Burkhard]

Bah!  You can't "eliminate" the need for vaccum advance UNLESS you are doing
ALL full-throttle driving. Mechanical advance only is fine for a race car,
but on anything that is driven anytime part throttle (including all streeted
cars), you will be underadvanced and the throttle response & fuel economy
will suck.  All spark ignited engines need to increase the spark advance at
part throttle loads. There's no way around it. If you crank up the static or
centrifal advance to (ahem) "compensate" for the lack of a vacuum advance,
you will then be over-advanced at full load (prone to knock and/or losing
torque from the optimal timing).

The fact that GM didn't have a V.A. on the turbo distributors was only
because they were trying to keep the whole deal simple and having BOTH a
pressure retard and vacuum advance would have made things more expensive.
But one level of spark advance (reardless of load!) at all engine speeds up
to 4,000 rpm (or is it 4400, I forget...) is no way to run an engine,
though. No modern car dispenses with load-varied spark advance. Sure, it's
all done electronically (no distributor), but the optimum spark advance
ALWAYS varies a lot with load. No way around it whether a turbo engine or
not...  To not do so means you lose part throttle torque (feels unresponsive
and you have to go deeper into the throttle to make the car move) and also
fuel economy (on account of a drop in indicated thermal efficiency from the
mistimed combustion).

Jim Burkhard
Air, Fuel, and that other one... Now what was it...?

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Patio Matt wrote-

> You can also "modify" / re- curve  the existing unit [  
> change the springs / 
> remove ONE spring, etc.]  if you understand what you're 
> doing...and even 
> eliminate the NEED  for the VA  to get full advance...