Re: More performance mod questions (ignition)

[christian147@domain.elided]

>Won't any spark ignite the mixture the same?
No, just any spark won't form a viable flame kernel.  Different operating
points have different problems.  At low throttle openings the air fuel
charge is so rarified that having a combustible air fuel mix in the
plasma zone (spark gap) when the spark happens is kind of hit or miss. 
Inductive systems tend to create long sparks so that helps the chances. 
At WOT the combustion chamber is such that the ionization voltage goes
way up.  This reduces the number of electrons that can be pushed across
the spark gap (much as kinetic energy is proportional to the square of
the velocity, electric energy is proportional to the square of the
voltage, so a small increase in ionization voltage is a large decrease in
the number of electrons that can flow).  Cd systems tend to produce short
sparks, reducing the chances of having the right mixture of fuel O2 and
spark in the right place at the right time.  MSD and others try to solve
this by producing several sparks in quick succession.

The only good discussion of what it takes to get a viable kernel started
was in a class I took from Dema Elgin of D. Elgin Cams.  From the
description he used it is a wonder a flame ever get lit.

All that said, the only reliable way I know to tell if an ignition up
grade will improve performance is to test-up grade-test.  If the tests
show an improvement over the baseline then the original was marginal. 
Many people, myself included, tend not to do the baseline test until we
suspect a problem with the system.  This skews the test in favor of the
upgrade.  So make sure what you have got is in top shape and function as
it should and take with a grain of salt others testimonials.   Here is
mine, Carbed 1750, points and condenser ignition system, coil suspect
(possible partial short).  Replaced with MSD 6AL and Blaster 2 coil. 
Results: Improvements across the board, any way you want to measure it,
power, gas mileage, smoothness, Beth even reported it was quieter (???). 
So I can report that the MSD system was better then that we had before.  

If you can borrow the proposed systen from a friend to try first you can
save yourself the gamble of it not making a differance.

Chris Hall

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