Thanks, Theo
As you can tell by the model years, my exposure to the Ford units is
many years old, and if there was a coil crammed in that V-8 Mustang II
it was hiding pretty good. I never imagined it released any more than
one spark per firing, but that box was as big as thee CD unit I used to
have (which did have a coil).
I'd be willing to wager that the "resistance wire" you mention is a
replacement for the ceramic resistor used in our cars to drop running
voltage to 9 volts after allowing a higher voltage coil initiation
during start mode (12 volts), when the ignition key is in the run
position, just like our stock resistor, wiring on the Tiger.
Being unsure, I did say "and release it in a very large surge through
external, or internal voltage transformers (coils), creating a huge spark".
It was not bad, compared to the standard design, and mine was many years
old before quitting on me. It was then I found so many "no label"
cheapy replacements, and at least 2 different Ford modules, with 3 or 4
wires. Not interchangeable.
The use of a magnetically sensitive semiconductor (Pertronix) is indeed
similar to the multi-pole center iron sender, as used in the Ford
distributor, on a functional basis.
My only interest in the Ford design is the "arc-free" large cap, which
snaps on to a coupling collar to the old distributor body, to limit
arcing inside the cap. Steve Sage may (or may not) have learned this
lesson. I am unsure as to whether this will solve all the issues, so I
procrastinate on the P II as the P I keeps running, and running,..... :-)
I wouldn't think the Duraspark had a tach issue, simply out of the time
period that the units were made, but it is good to know that someone has
their firm experienced grip on this.
I know I may offer some aged experience which is incomplete. Please
excuse any errors of omission. I'll have to eat those of commission.
(or "mis-spoke", as they say in politics now.
Thanks for the info.
Steve
Steve
Theo Smit wrote:
> Actually, the square box Duraspark module has much more in common with
> the Pertronix than it does to an MSD or Jacobs multi-spark ignition.
> The Duraspark is not a capacitive discharge system, it doesn't use a
> high-voltage coil drive to decrease the coil saturation time, and it
> only releases a single spark per trigger event. You can use the
> Duraspark module with the stock tach wiring and internals - maybe not
> all of the original tachs will take it, but the example I've seen
> worked just fine.
>
> One note: This link (below) suggests that the Duraspark is powered
> through a length of resistance wire. This is the first I've heard of
> that, but I haven't researched the Duraspark module very deeply
> either. If you are looking to use the Duraspark module then you may
> want to really figure out how the factory intended it to be wired.
> http://www.therangerstation.com/tech_library/DurasparkII.html
>
> Then again, this link here suggests that the coil only is powered
> through the resistance wire and doesn't say anything about the module.
> This is more intuitive - the module itself should be able to handle 12
> volts, while the coil itself should be wired according to how it's
> designed - if it needs a ballast resistor or resistance wire then you
> must use one.
> http://www.crazyformercurys.com/durasparkii.htm
>
> Best regards,
> Theo
>
>
>
> Steve Laifman wrote:
>
>>
>>
>> The square box (Duraspark in Ford lingo) is much like other external
>> ignition systems, like the Mallory MSD 6 style capacitive discharge
>> system. These add energy to a large capacitor, which stores it, and
>> release it in a very large surge through external, or internal
>> voltage transformers (coils), creating a huge spark. It has issues
>> with tachs of an older vintage, as Theo points out, and has the cure
>> for.
>
>
>>
>> Steve
>>
>
>
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Steve Laifman
Editor
http://www.TigersUnited.com
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