Vacuum advance unit

[CJG]

Can any of you more knowledgeable chaps on here tell me what effect a blown diafram in the vacuum advance unit have on running the stag. My unit does not move when i suck on the pipe and there is no resistance its like sucking on a straw in fresh air.
Checked the pipe and connections and they are fine
Thank's Chris.

[Phil S]

you will be running on a slightly weaker mixture due to the air leaking in..but only a little.
the vacuum advance system is an economy set up to advance the timing when you come off the throttle, this weakens the mixture, so the timing needs to be advanced to allow for a slower flame front burn on ignition.
early performance distributers had a greater mechanical advance curve and no vaccum unit (Cooper s).
so you can temporarily block it off while a new one is obtained.
Phil

[CJG]

Thanks for the reply Phil, would this cause the lumpy running at low revs, or should i be looking else ware for that.

[Phil S]

It will not be helping, push a self tapping screw in the end of the hose for the time being.
Phil