Thread: vacuum advance?

You can pull the hose off at the pleniun chamber and suck on it. If you keep sucking air it is time for change. If you get resistance start the car and suck, see if the engine revs change.

You can get reconditioned ones from places like Performance ignitions in Nunawading Vic. Last time it was around $69 change over.

And after you do the suck test, get a xenon timing light, (ebay etc) mark the timing wheel on the TDC timing mark with a bit of chalk.
and rev the engine as you shine the timing light at the harmonic balancer
if its working properly the chalk will move (advance) as you rev and come back as the revs drop.

[ame="http://www.youtube.com/watch?v=rDXDV0ZO280"]Checking Ignition Timing - YouTube[/ame]

Same principle as the VDub ,
If the Vacuum advance diaphragm was stuffed the mark would not move as the engine is revved

if its working properly the chalk will move (advance) as you rev and come back as the revs drop.

You are confusing vacuum advance and centrifugal advance.

Vacuum advance on a 3.9 is "ported" and only works with small throttle opening and high vacuum so show not very much when the engine is revved with no load.
Just suck on the vac hose with the dizzy top off and you will see the baseplate move if it is OK.In any case it is usually enough that the hose will stick on your tongue..
The centrifugal advance test is valid as this often siezes on an unmaintained dizzy. you can tel by just turning the rotor , it should turn about 5Mm and snap back. If not drop soime oil down the shaft and leave for a while.
Regards Philip A

Thanks guys, I just did the "suck test" and I got no resistance at all with the engine not running and running.