In Fig.1 of the well written and informative article, the distributor on the right shows a defective mainshaft. This is not well known among the Corvette community, and notifications by me in 2012, to all the major vendors resulted in LICS at least, fixing the problem. The problem involves the orientation of the SHP autocam onto the distributor shaft. As shaft RPM increases, the "heels" of the weights are designed to ride up upon the slopes of the autocam's flanks thus creating higher spring resistance and consequently, the rounded flank of the "football" must contact the weights' short leg, not the flat flank. An assembly problem ongoing for the last few years has resulted in the autocam ("football") being installed upside down on the shaft, which is easy to do if the spring pins are first installed upside down as well.
As I said before, LICS was the only vendor that replied to me that they have fixed the problem, and sent me a photo to prove it. In the graph on page 41 of the article, you'll notice that the incorrectly assembled SHP shaft causes a slower mechanical advance program than for the standard/HP shaft. Because of low dynamic compression of SHP engines compared to HP engines (because of very late intake valve closing as well as extremely slow lobe ramps), they respond well to faster, not slower mechanical advance programs. The excellent article shows just the opposite.
In the following photo, the correctly assembled shaft is shown above the installed, incorrectly assembled shaft:
As I said before, LICS was the only vendor that replied to me that they have fixed the problem, and sent me a photo to prove it. In the graph on page 41 of the article, you'll notice that the incorrectly assembled SHP shaft causes a slower mechanical advance program than for the standard/HP shaft. Because of low dynamic compression of SHP engines compared to HP engines (because of very late intake valve closing as well as extremely slow lobe ramps), they respond well to faster, not slower mechanical advance programs. The excellent article shows just the opposite.
In the following photo, the correctly assembled shaft is shown above the installed, incorrectly assembled shaft:
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