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Author Topic:   Dwell Tach Question
Robert K

Posts: 706
From: Nashville, TN
Registered: Apr 2000

posted 06-30-2005 02:42 PM     Click Here to See the Profile for Robert K   Click Here to Email Robert K     Edit/Delete Message   Reply w/Quote
Does anyone know what the difference between a Primary dwell/tach and a Secondary is ? I didn't know there were different types. Which one is preferable or the best type to have ? Can someone please educate me on this ?

67convertible 289/auto
65fastback 302/4sp

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Posts: 662
From: Moreno Valley, California
Registered: Sep 2004

posted 07-02-2005 12:21 AM     Click Here to See the Profile for stc65coupe351w   Click Here to Email stc65coupe351w     Edit/Delete Message   Reply w/Quote
Does this help?
Almost every day we receive an e-mail or telephone call on how to set the breaker points on single, but mostly dual-point, distributors. It surprises me as to how many people "that have been Doing This For Years" still do not really know how a dual point ignition works or how to correctly adjust the breaker points.


There are many myths surrounding dual point ignitions, here is a list of the most popular.

Dual Point distributors operate opposite cylinders or opposite sides of the engine. Absolutely false! The dual point distributor only increases coil output (duration) for better performance in spark energy output from the coil, and for better high RPM operation.
A point set is two breaker points. Not true. A point set is ONE point set, meaning a set of contacts is part of just one point set. Dual point distributors require (2) sets of points, which would be four contact points.
Dual Point distributors are set with a matchbook cover for gap or a feeler gauge. Well, this is half right. The gap is actually a starting point. Correct point gap is only accurately set with a dwell meter. Different distributor designs, brands, and engines (4 cylinder vs. 6 cylinder vs. 8-cylinder) can and will have different required settings.
Dual Point ignitions are better than electronic. Absolutely false. In many cases a point ignition "may" be more reliable if your electrical system on your vehicle keeps killing electronic ignition modules, but points are definitely not better than electronic. Electronic triggers offer better coil saturation, better RPM, no need for adjustments, and smoother running at all RPM levels.

-351w Bored .30-351w Heads Fully Ported
-Custom made Ford 9" 3.70
Pics Michael

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