Duraspark I verses II

eeyore

Well-known member
Is there any detriment to using a Duraspark I over the Duraspark II? Is the only difference the cap? What was the purpose of the change Or Changes?

Thanks!
 
Yes, the only difference is the cap and rotor button. I think it was done to alleviate any potential arcing problems, but I do not know. It might have been simply to allow them to use the new plug wires across all of their engines.
 
Theoretically, DS II uses larger plug wires, for improved insulation, though the diagram I've seen makes the difference insignificant. Good 8 mm wires will likely outperform cheap 10s. On the other hand, the larger cap and rotor are supposed to reduce spark tracking inside the cap, but you can help that by applying light coats of dielectric grease between the contacts. MOPAR products used a small cap, with strategic dabbing of dielectric grease. I'm using the DS I cap because the large cap won't clear my PS Pump. On the up side, the DS I looks almost stock. ;)
P1010001.jpg
 
The further apart the terminals are the less likely that cross-firing inside the cap will occur. This was more of a problem with the earlier V8 caps as those terminals were pretty close together. Back in the days of breaker points this wasn't much of a problem but with the advent of smog laws the manufacturers needed to run leaner mixtures which are somewhat more difficult to ignite. Enter the modern HEI "types" of ignitions by the various car makers; suddenly the higher voltages are more difficult to contain so they had to re-design to cure that problem.

A mild street driven Ford Six can get by just fine with the small diameter cap so long as you don't get crazy with the plug gaps. Bigger gaps require higher voltage to fire; as does lots of turbo boost.... 8) 8) :shock: :LOL:
Joe
 
I need the small cap because of power steering. Was the small versus large cap particular to any model years?
 
aahsac":3lbq4blt said:
Was the small versus large cap particular to any model years?

the small cap was used on 1975-76 models.

it was phased out in late '76 for the new improved two-piece cap.
 
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