Difference Between Dual Vacuum Dizzy vs. Single Vacuum Dizzy
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Difference Between Dual Vacuum Dizzy vs. Single Vacuum Dizzy
We added a 76 duraspark system to our 72 390. In looking up some parts it appears we have a dual vacuum dizzy. I am curious as to the reason for this type of system vs. the standard single? Are they interchangeable?
Thanks! Dan
Thanks! Dan
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From: East Central Ia
Should interchange OK. Dual type was usually used for emissions, a temperature controlled vacuum switch would turn on the vacuum to the retard side when it was necessary. At least thats my take on it. I've replaced them with the single when they went bad, no emission test here (Yet).
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Correct. The dual vacuum dizzy was strictly for emissions purposes. During acceleration, the vacuum advance worked as normal to advance the timing just like a single advance unit. On deceleration, the other side worked to quickly retard timing as the engine was no longer under a load and the timing advance was no longer needed. I forget which pollutants this method was meant to control.
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If you can take it back, do so. If not, just don't hook up the retard side. It will work just fine.
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Ok, now I am really curious as to which Dizzy I have. Here is the Ford # Dozf 12131a 17, can anyone tell me if this is a dual vacuum? I do see a possible port on the top / side of the vacuum mechanism which I suppose could be the retard side of the dual vacuum system. I hate resorting to pictures and brief descriptions, but that's what I had to do at the store the other day, no expert help behind the parts counter.
Thanks!!
Thanks!!
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Joined: Jan 2002
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From: Centreville USA
Ok, now I am really curious as to which Dizzy I have. Here is the Ford # Dozf 12131a 17, can anyone tell me if this is a dual vacuum? I do see a possible port on the top / side of the vacuum mechanism which I suppose could be the retard side of the dual vacuum system. I hate resorting to pictures and brief descriptions, but that's what I had to do at the store the other day, no expert help behind the parts counter.
Thanks!!
Thanks!!
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Thanks for the info. This only has one port on the end of the diaphragm. If it is from a 70, then this originally was not a Duraspark, true? Or were they available?
This is interesting, below are two pictures, each one was an option for replacing our Duraspark. Dizzy 1 has a much larger diaphragm, as mine does. I am curious about the differences.
This is interesting, below are two pictures, each one was an option for replacing our Duraspark. Dizzy 1 has a much larger diaphragm, as mine does. I am curious about the differences.
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From: Centreville USA
Thanks for the info. This only has one port on the end of the diaphragm. If it is from a 70, then this originally was not a Duraspark, true? Or were they available?
This is interesting, below are two pictures, each one was an option for replacing our Duraspark. Dizzy 1 has a much larger diaphragm, as mine does. I am curious about the differences.
This is interesting, below are two pictures, each one was an option for replacing our Duraspark. Dizzy 1 has a much larger diaphragm, as mine does. I am curious about the differences.
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