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Distributor is Delco 662W from a '36 1401 Eight. I'm questioning its operation because a timing light check showed the spark retarding as engine speed increased.

Pulling the distributor, removing the breaker base plate and spreading the weights by hand causes the rotor shaft to shift clockwise; the same direction as the shaft rotates while in car.

Obviously, this is incorrect, as advancing the spark requires the shaft move in the opposite (counterclockwise) direction.

So, my question is: Are the internal parts pictured here correct for the Delco 662W, or has someone inserted incorrect parts? (I colored the weights so they'll stand-out in the photo and marked the location of the two springs with yellow lines). I tried repositioning the weights but this is the only positioning in which the parts "mesh" and move smoothly.


Thanks for any advice or words of wisdom!

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Needy

Your distributor is working properly, the cam and roter are rotated in the same direction as the shaft rotation to advance them in relation to the cam shaft and crank to cause the points to open sooner in relation to the crank and cause the spark sooner in relation to the crank and cam position, (ie, advanced).

If you need any help contact me as I am in Snoqualmie, WA.

John

John: Thanks for the expert clarification! I now realize that distributors which advance the spark by moving the rotor SHAFT, must move the shaft in SAME direction as shaft rotation to advance.

Whereas distributors which move the BREAKER PLATE to advance, move the breaker plate in the direction OPPOSITE of shaft rotation to advance.

It does make a difference which type is being considered!

Typically distributors after the mid-30s utilize two mechanisms in the same unit to obtain "total spark control"; the breaker cam movement is a function of the centrifugal advance and the breaker plate movement is a function of the vacuum advance (retard) function. I can't say I've ever seen or heard of a distributor that used the centrifugal advance mechanism to move the breaker plate - but that doesn't mean there isn't some uncommon unit that does so.