I switched to a 60's Ford cap and rotor on a 1984 Duraspark II ignition system. Worked great. Then, I switched to pertronix for less components/wiring.
I believe you can take off the adapter for the large 2 piece cap and use a 606's Ford small cap and rotor, depending on exactly which dist you have....
The "big" Duraspark cap is fitted to an adapter,...which sits between the distributor housing, and the cap. Simply remove it, after removing the cap; it uses the same clips, and replace with a "standard" ign Ford cap and rotor. The Ford dissy housings are the same, beginning with around 1957. Other than clearance problems,...why use the smaller cap and wires ? 4TTRUK
Clearance is my issue. I am bending a new fuel line from carb to pump and it hits the bigger cap. I am also theorizing (judging from the pix listed earlier in this thread I'm validated) it looks better to me. I'm I to assume the rotor is interchangeable between the dura and the small style caps?
The size of the rotors for Durapark cap and small cap are very different in size. Small cap rotor on left in pictures.
The small cap looks so much better but ford used the big cap to eliminate spark jump in the small cap. I remember having cars with the small cap and had no issues so go figure . Big hei caps look like hell on anything.
To use HEI style wires, use a cap for an International Scout 5.7L. They are the small Ford size and rotor but use HEI style wire ends. My local NAPA got one for me. Here's what Summit sells. http://www.summitracing.com/parts/SMP-AL482/ All you need to do is open up the square hole over the vacuum advance. It's shadowed in the cap and takes 20 seconds with a file. SPark
I converted my 292 YBlock to Duraspark II in my 57. Used the 57 cap & rotor. I think the two piece would have fit but would have looked pretty dumb.
The problem came from the higher spark energy of the Dura Spark ignitions over the earlier points systems.
large cap will fit in place of small cap, so visa versa. I have large cap on my 302, had small. Get the appropriate rotor and good to go. May have to change plug wires as the two sizes may have different style towers on the cap.
I have been using the small points style cap on a Duraspark distributor for many years without any problems,I am also using a cut to fit set of plug wires that are probably for a points ignition too. That big cap looks horrible in a 50s or 60s car and will probably go with the small cap on my galaxie when it needs a set of wires.
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