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Originally Posted by West Coast GTO
Initial timing was set at 20 BTDC and ran 13 inches vacuum at 800 rpm and the engine really liked that timing.
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Fairly pathetic vacuum given the amount of advance and the RPM. Radical cam?
Quote:
Originally Posted by West Coast GTO
Summit unit uses correct pole/module set up for Pontiac
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I'd love to see a photo of the pickup coil and ignition coil color codes. My guess is that you've got Chevy/Cadillac "Yellow" color-code parts. (Which would make little or no difference except perhaps during cranking.) There's no difference in the modules--just the coils.
Quote:
Originally Posted by West Coast GTO
I changed the springs from the Davis unit to the new Summit unit to replicate the Davis vacuum setting and verified with a vacuum pump prior to install.
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What "springs" are those? The only (accessible) springs in a Delco distributor are for the CENTRIFUGAL weights; that has NOTHING to do with the vacuum advance. You'd need to swap the weights, center-piece AND the springs to get the same centrifugal curve. The springs control how fast the curve comes in--but not the shape of the curve.
There's a spring in the vacuum advance canister, but you'd have to essentially destroy the canisters to get the spring out of one and put it in another, and "good luck" getting the thing back together again.