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More vacuum advance mysteries

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WALTER

WALTER

Jedi Hopeful
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I went to check out my vacuum advance. A couple things seem to be wrong. (1)when I hooked up my vacuum pump to the distributor it would not rotate the plate. I could move it by hand while under vacuum then it would rotate back when vacuum was released. (2)I could not get vacuum from the manifold. I took the small plate off at manifold. I got vacuum from mounting screw hole but not from tiny whole where it's supposed to come from. Small wire went in about 1/2", sprayed w/carb cleaner no difference.

So, what might be clogging small hole and do I need to clean & lube my distributor?

Thanks
Walter
 
HI Walter,First check out the Vacuum advance as indicated by JEFF above. If the plate does not move with it,You may have old dried out lubricant or lack lub in the assembly. The small Vacuum hole leads to a small boring in the carb casting that may be plugged with carbon and should be cleaned out.__Fwiw---Keoke
 
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So, what might be clogging small hole and do I need to clean & lube my distributor?
Thanks
Walter

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Maybe nothing is clogging the hole (vacuum advance port). It is designed to be cut off from manifold vacuum when the throttle plate is closed or at idle. The throttle plate only uncovers the hole when the throttle is advanced. It may be that when you probe the hole you are running into the throttle plate. Try opening the throttle plate a bit when you probe. Better yet, apply some spray carb cleaner to the outside of the port fitting & see if it comes out inside.

The point mounting plate is mounted to it's base plate with a bearing under the plate. With the vacuum chamber arm disconnected, you should be able to easily rotate the point mounting plate. If not, remove & check/clean the parts or find what is restricting the movement.

This is a good time to apply vacuum to the advance mechanism & see if it moves freely & holds vacuum before reconnecting it to the point plate.
D
 
Thanks guys, you're awesome.

I didn't know about the throttle plate.

Walter
 
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