How much mechanical timing advance is there supposed to be on these Disco distributors? My vacuum advance is working fine (I can advance the timing by drawing on the hose), but my timing only moves maybe three degrees if I raise the RPM of the engine (with the vacuum advance unhooked). It seems like it should advance more than that...

 

I could be wrong, but I think the centrifugal advance on most distributors almost completely advances at an engine speed much slower than your average idle speed, therefore it shouldn't make any difference when you blip the throttle.

 

My guess is that the prior owner goofed up the distributor when changing the rotor (lifted up, which pops the springs) and that my mechanical advance is toast until I pull the distributor. That explains why:

1) I'm getting a whopping 9 mpg even though I drive like I'm driving Miss Daisy around.
2) For it to have any sort of power, the base timing needs to be set at 12* BTDC (and it doesn't ping...since the timing isn't advancing).

 

Wow... this sounds soooo familiar. I had the same problem (caused by myself) when the springs/weights fell off while I changed the rotor. It turned out to be an easy fix. You can access the mech. advance gutsby removing the plastic cap and rotor, then take off the snap ring retaining the inductor rotor (metal star-looking piece) and pulling off said rotor. Now you can remove the screws holding the cheesy plastic "do not remove" cover and the stator assembly. I took the whole distributor out for this job, but maybe you don't have to. The mech weights fit back together like pieces to a puzzle, so you can figure it out if you stare at it long enough. Then pop the 2 springs back on and put the whole thing back together. Takes about an hour or so and makes a world of difference.