Distributer Vacuum Advance

[RobH]

Just had MOT and service done, told distributer vacuum is leaking and would need replacing, it hasn't been replaced and the van was running really well today, so what's the vacuum advance actually do and how soon should I get it replaced?

[kevtherev]

told distributer vacuum parking

beats me... unless you typed it wrong and meant leaking

[RobH]

That's the one bloody tablet correct, it's leaking. I'd like to know what it actually does in order to determine whether to replace imminently or after holiday.

Cheers!

[ed_the_robot]

It advances the ignition timing as the engine revs increase via a vacuum effect from the carb to the distributer.

If there is a split in the vacuum hose it will not operate properly.

Our Doris's vacuum advance was plumed in wrong, so wasn't actually working. We had driven nearly 1200 miles with it like that, simply not knowing she should have a bit more power at the top end! We were loosing around 10 mph of top speed!

I'd be more concerned with the air leak causing a weak mixture and possible stalling. That was the other symptom we had.

[tandemsandy]

Replaced ours a few months ago.
had been struggling for power pulling away and on hills. Available from Brickwerks and pretty easy to change. Get a new O ring to go with it, which might cure the inevitable oil staining on to of the crankcase, our O ring was completely solid like a plastic ring. Worth replacing the hose if its the original one, some nice silicon vacuum hose from eBay is pretty cheap.

Rob & Sandy