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Question from a Dummy about distributor

R

Richard G.

Well-known Member
I have been working on tractors, cars and trucks for almost 60 years.
The centrifugal advance in a distributor changes the timing when an engine starts running.
I know the weights expand outward, but what moves to advance the timing?
 
The point plate moves. If you have something with the old vacuum advance you can pop the cap off and pull the hose off the manifold and then suck on the hose and watch the plate move
 

Vacuum advance moves the point plate, centrifugal advance moves the distributor shaft cam through a combination of weights and springs, mounted to the shaft below the point plate. That mechanism is what you are moving when you twist the rotor button, and it turns back when you let go of the rotor.
 
Some distributors the weights move the cam and some the weighs move the plate the points are on. Yes the plate can rust and stick. The cam can also rust to the shaft so it won't move.
 
(quoted from post at 17:25:16 08/13/22) Some distributors the weights move the cam and some the weighs move the plate the points are on. Yes the plate can rust and stick. The cam can also rust to the shaft so it won't move.
Click to expand...

I'm drawing a blank on this, what distributor has a plate, the points are mounted on, that is moved by the weights. Interested, as I can't say I ever encountered one.
 
on my 860 the area below the points plate was packed solid with dirt / hay etc. would allow erratic timing issues until i discovered it and cleaned it out. remove your point plate and take a look
 
The distributors with which I'm familiar work this way: Vacuum advance moves the BREAKER PLATE OPPOSITE the direction of the distributor rotation to advance the ignition timing. Centrifugal advance moves the DISTRIBUTOR CAM in the SAME direction as distributor rotation.

How does the centrifugal advance work? The distributor cam is not fixed to the distributor shaft, but rather is connected via the centrifugal advance mechanism. This mechanism consists of a couple of springs and weights, and the weights apply a camming force that causes the distributor cam to turn relative to the distributor shaft. It's all real obvious if you tear apart a distributor.
 
Items # 4,8,9,10 spin together.......
However, # 8 advances the point at when the points open as the RPM increases...
# 8 causes # 10 to advance..
No vacuum advance...
# 10 is driven by the tension of the two springs
Ferguson TEA-20
#10 is held in place so as it cannot move vertical by a fastener # 21.
Bob..
cvphoto133135.jpg


cvphoto133137.jpg


cvphoto133139.jpg
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(quoted from post at 17:52:47 08/13/22) NOTE I said vacuum advance I did not say the weight type advance
Click to expand...
n that case, read the darn post before responding! He asked about centrifugal advance.
 
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