Distributor slop

[capt_furious]

I know there's not supposed to be any play in the shaft, but is it supposed to be able to rotate at all with the engine off? I can get about 30 degrees of turn by hand, although it does center itself.

 

I'd think you wouldn't want any rotation at all, as this would trash timing. Do I need a new(rebuilt?) distributor, and if so, where can I get one without breaking the bank?

[X64v]

If you can get a lot of play to one side, but not to the other, and it resets itself, all you're doing is actuating the mechanical advance by hand.

[BRAAP]

Capt,

As "X64v" stated, what you described is PERFECTLY normal. That rotation you described is the mechanical advance integrated in the “distributor system” and the tension you feel that returns the rotor back to its original position are the mechanical advance springs that are attached to the fly weights. As the engine speed increases, those fly weights fling outward and advance the ignition timing allowing the engine to run smoothly and efficiently at varying RPMS with as close to ideal ignition timing for that RPM.

Altering the mass of the fly weights and/or spring tension will alter at what RPM the mechanical advance will begin, how aggressive that curve is in regards to engine RPM, and at what point max mechanical advance arrives. When “recurving” a distributor, altering the flyweights and/or spring tension is how that is achieved.

 

With modern Distributorless systems, that advance curve is altered via the ignition map, much like the fuel map. Some dizzy’s are also capable of the electronic means of altering ignition advance such as the late 280-ZX Turbo set ups.

 

Any how, hope that helps clarify.

[capt_furious]

...I'd forgotten completely about the mechanical advance. Thanks, guys. Was worried I'd have to drop a load of dough on a new distributor(I know my timing chain is okay, it was replaced a year ago).

 

...and knowing is half the battle! G.I. Joeeeeeeee...