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Odd facts/things about the transition to transistorized ignition systems on the 280Z


Zed Head

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I learned something interesting in another thread about Nissan's move to electronic ignition systems, and thought it might be interesting to collect some stuff here.

Nissan went from points to electronic ignition in 1974 with the 260Z.  The coil still used a ballast resistor to limit current at long dwell times (low RPM).  Spark gap was still specified at the gap used for points.

1975 and 1976 used the same basic system, an electronic module, a ballast resistor, and a coil, with spark plug gap set to the smaller points system gap.

1977 used the same basic system but opened the gap up to about .040" instead of the old ~.035".  

1978 got rid of the ballast resistor and also kept the wide plug gap.

 

Just collecting some thoughts while they're still in my head.  I searched around the internet and found quite a bit of confusion about the ballast and 280Z's.  Many people don't even realize that they have them, and assume that only points systems have a ballast resistor.

Here is the carpartsmanual page for the ballast.  The list doesn't quite match the picture, kind of confusing, the drawing says "to 74".  So, does the 1977 ignition module pass more current than the earlier modules?  Is that the difference that allows a wider gap?  

Interesting also that the first ignition  boxes were aluminum with fins, to dissipate heat.

http://www.carpartsmanual.com/datsun/Z-1969-1978/electrical/engine-electrical-fitting/3

 

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Here's the "Trignition" ignition module page.  (Trignition didn't really catch on, did it?).  The last part change was July of 1976.  Implies that 77-78 were the same part.  But it doesn't seem that way in reality.

Could help somebody looking at part interchanges if they don't want to switch to GM HEI or Pertronix.

http://www.carpartsmanual.com/datsun/Z-1969-1978/electrical/engine-electrical-fitting/10

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I'm not sure how they were able to get rid of the ballast resistor in 78. There are several possibilities, but I haven't really looked into it.

If I get the chance, I'll poke around a little with that 78 module I have and see if I can figure out how they were able to function without the ballast and not burn anything up.

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