Dizzy Question - Micro Adjustment Wheel 25D Dizzy

[Jim_Gruber]

I've been having some timing issues and finally resorted to doing some static timing this AM. The micro adjustment wheel on my 25 D Dizzy was turned all of the way in one direction. I adjusted several turns 5-10 back the other way and then reset static timing. I'm now noticing the vacumn advance cannister seems really loosely fitting in the dizzy. Meaning I can phyically pull on the cannister and get the vacumn advance to move. Doesn't the Vacumn advance housing sit firmly in place, possibly bolted in place or is it just a friction fit.

If this thing is all loosey goosey this could explain why I can't get Bugsy to run correctly. Starts fine and then give it a little gas and it misses. Keep above 2,500 RPM and it pulls fairly strong. No power below 2,500 or so.

How does the vacumn advance fit into the dizzy. Bolted or friction fit.

 

[Trevor Jessie]

Isn't there a spring in there that keeps tension on it?

 

[Jim_Gruber]

There could be but I don't see one without pulling it out of the car. There ought to be something it there to provide some tension. Could have slipped off when I was adjusting wheel or broken somehow.

 

[Jim_Gruber]

The whole housing seems to shift in and out of the dizzy if I pull on it. When I've set timing before I've always used it to rotate the dizzy for better leverage. Oops just realized I forgot to tighten down the dizzy after resetting timing.

 

[Trevor Jessie]

https://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=29338

In that diagram if #10 is broken, then the vacuum advance unit would move about.
... I think.

 

[Jim_Gruber]

How about if I turned it too far out, loosened it too far, looks like that could cause the same issue. TIme to pull it out and see what I can find.

 

[Sarastro]

There's a spring-like connection between the diaphragm and the plate on which the points are mounted. It's fairly easy for this to come loose, and then you not only lose vacuum advance, but the plate is free to move around, sothe timing can wander. You might be able to see if this has come off without pulling the distributor, but in the long run it might be easiest to pull the sucker. Then, at the same time, you can do any necessary cleaning, lubricating, and parts replacement.

Check all this in a shop manual. I'm going by memory, since I'm not at home, and that's always dangerous.

 

[DrEntropy]

A spring with a small loop pulls on the vacuum advance mechanism to keep it "home". If it wobbles and is loose the spring may be detached from the post or broken. The "wheel" actually should be set at about half its travel and each "click" is something like a 1/5 of a degree either way. "Vernier adjustment". Actually Steve is *almost* correct... the arm from the diaphragm is attached to the points' stage via a link to vary the timing. The spring is strictly there to hold tension on the diaphragm housing so it CAN move the arm to vary the timing.

Pulling the dizzy and benching it will allow a good exam, Jim. Just be aware of the spring steel "clip" making contact with the toothed wheel... it can sometimes jump out of the dizzy body and hide from you as you unscrew the wheel... and there's a wire retainer at the end of the threads you will need to fiddle off there to unscrew the wheel completely, too.