Will ask the question before I rebuild the distributor: Are the springs under the plate really 2 different springs? The workshop manual has an exploded pic of the dizzy and the parts listing that goes along with the pic just says 2 springs which at first thought, to me anyway, imply the springs are the same. Upon comparing 2 spares I have, both dizzys have the springs different; one is tightly coiled and the other loosely coiled as shown in the pix.
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Changes the advance rate. If you look in the factory manuals, the advance graph has two slopes - those are the different springs. One goes all-in easily, the other comes in later.