Distributor vacuum

[RubbishFettler]

Hi all

I am replacing the vacuum unit because it was not holding a vacuum. When I have taken it off I have found that the pin which the arm hooks onto does not move. Am I right in thinking that it should and that the unit was not working because the dizzy is seized? When the vacuum unit is off you can hardly suck air through it, which would suggest the unit is ok. Has anybody had the same and if the dizzy is seized, know the best way to free it?

Just as a side issue, if the the vacuum unit does not hold a vacuum when it is fitted, would this effectively create a source of un metered air into the plenum, thus weakening the mixture?

Cheers

Steve

[Wedg1e]

The advance/retard plate should be free to rotate within limits, I'd try liberally spraying Plus-gas or similar sround the spindle and prying the plate with a screwdriver.

Yes, a leaky vac capsule would introduce unmetered air.

You can strip the entire distributor down with care; you have to drive out the pin securing the helical drive at the bottom of the shaft first.

[adam quantrill]

You should be able to suck on the vacuum pipe and see the timing move by about 10 degrees.

I've never known the idle speed to chance when letting this pipe let air into the system, so if it did allow unmetered air in, it isn't much. It's a thin pipe.

[RubbishFettler]

Thanks guys, I took the dizzy off last night and was able to free it up with WD40, The vacuum advance is working now, when I took the car out it was much smoother, performing far better at low revs.