Hi, I recently bought a Cardone part # 30-2808 distributor for 1957 and later block. I hooked a vacuum hose to the advance diaphragm to check
operation before installing. (I'm replacing my 1955 load-a-metic distributor). The advance arm from vacuum can would not move even though the advance 
plate in the distributor is free. I provided as much suction as possible using my mouth. I removed the diaphragm from distributor and again tried to actuate the arm while sucking on the vacuum hose. I couldn't get it to budge. Its seems as if there is a very tight spring under the diaphragm and it takes a huge amount of 
pressure to overcome. Does this distributor require some centrifugal advance to kick in before the vacuum will pull the diaphragm / arm ?? Anybody with experience with this distributor care to chime in? Thanks in advance,  Brett

1955 tbird 

Motorcraft part # 12127

1955 tbird 

Many of the vacuum pots are adjustable - it takes a 3/32 Allen wrench - that is long enough to reach down directly through the vacuum port. To limit the amount of vacuum advance on those units, you turn the Allen screw inside to preload the diaphragm spring. It could be - that your unit has the preload set-up pretty tight already - and therefore takes a good bit of vacuum to make it move the arm. The direction the screw is turned to tighten it - is not the intuitive direction. You must turn them CCW (counter-clockwise) to increase the spring loading.
Can you run the engine as it sits now? And then use the existing manifold vacuum as a test source? I have a '74 Olds I use as a vacuum donor when testing the pots......................


 
 Steve Metzger       Tucson, Arizona

Those Mity Vacs are only $40 or less on Amazon. Put a vacuum gauge in the car, check your vacuum at cruise. You can then duplicate rpm and vacuum at the dizzy, and check your total running advance. With a second set of hands and eyes, you can plot the vacuum curve by inches. Really helps when tuning. Bleeds brakes real well, too.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

It should move when you suck on it, try Steve's suggestion see if it has an adjustment. While you have it in your hand maybe you want to modify it so you shorten your timing a bit and also you could try fit Mr Gasket D925 springs as well...? Jus' sayin'..



"Came too close to dying to stop living now!"

this is great to know, unfortunately i can feel no adjustment screw inside vac can...... And the motor is not running/no vacuum source.

1955 tbird 

I got out my handheld vac gauge and found that i can pull 12-15 inches with mouth vacuum, this does not seem to be enough to move arm in vac can.......

1955 tbird 

If your current vacuum chamber does not have a detachable vacuum hose end, I'll suggest another vacuum can.  If you do have a vacuum can that you can take apart, then remove the inner spring and related spacers and see if it was put together incorrectly.

Lorena, Texas (South of Waco)

yes Ted, I agree. It is not removable. I guess i'll source another can. Probably a lot easier than trying to return complete distributor to Advanced Auto and have them send another one........

1955 tbird 

good news ! Like greenbird suggested, my vacuum can IS adjustable. I had to use a punch to open up the hose nipple up to be able to fit a 1/8 allen wrench.  Turned it counterclockwise and was able to relieve some of the spring tension.  I can now advance plate with mouth vacuum as long as I give the arm a little nudge/help with a screwdriver. Its a start I'll be interested to see how the Edelbrock pulls  on it ...........

1955 tbird