Timing not changing w/ rpms

[74 Shortbed]

If the plate is seizing up it won't move, need to take the vacuum can off and put vacuum to it and see it the arm moves. Just replacing the cap and rotor is not rebuilding the distributor, it needs to be taken completely apart and cleaned and replace bushings/shaft if needed and new lubricant on the top and make sure everything moves freely..

 

[Honky Kong jr]

There's gotta be a way to test this. Shouldn't you be able to suck on the hose and see if the plate moves? If it doesn't, and you can feel air being sucked through, then the diaphragm in the canister probably broke, and it needs to be replaced. It sounds logical, but I don't deal much with vacuum advance.

Yes you hook the vacuum can to a hand held vacuum pump,remove the cap and apply vacuum to see if it moves and holds vacuum. The weighted portion should move a little. Or pull the distributor and spin it to see if the weights open up.

 

[RustyBuckets]

Actually i did try sucking on the vacuum adv hose and i could feel the diaphragm move and it didnt feel like it was leaking.