<VV> "Points" to ponder - Pertronix Issues
Frank F Parker
fparker at umich.edu
Fri Oct 28 09:56:20 EDT 2005
> The Delcotronic was in production until 1966 when it was replaced briefly by
> a Capacitive Discharge unit which led the way to the first HEIs in 1971.
> These early units had a much smaller diameter (drat, it is hard to tell this
> story without illustrations) than the 1973 HEIs which followed as it was
> found that 60,000 volts would arc over considerable distanced. These lasted
> until 1986 when the first Distributorless Ignition Systems (DIS) were
> introduced though the full transition took several years.
An interesting point about these ignitions was they failed alot from
mechanics poor technique in testing them. It was the early days of
transistors and they were not as sturdy or had as much collector/emitter
breakdown voltage as later designs. Someone would suspect the box of being
bad ( cause its always that newfangeled electronics ) and to test they
would pull the coil wire off and crank the car. The gap they held to
ground was usually way greater than a plug gap and the voltage would rise
trying to jump the gap till the back emf generated in the coil killed the
box. In testing the box, they killed it. Need to use an old plug to test.
I had a real good business fixing the old GM amps for all the local
racers. It was always the output transistor- I think a 2N174.
Modern stuff does not suffer from this problem but still not a bad idea to
use a spark plug to test.
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