Vacuum advance Lucas 35DLM8

[timeless]

I think I have a bad vacuum unit on my distributor. When I attach a vacuum pump the advance does not move and there is no vacuum build up. Normally this would indicate a bad vacuum unit but I wanted to see if there was something different about this unit that would cause that.

Also on the back on the vacuum advance unit there is another hose port. The PO had this blocked. Does anyone know what this is for or where the previously attached hose would go?

Thanks,
-Ed

[mearstrae]

Sounds like a bad vacuum capsule. If you can find one without the secondary vacuum port it might save you future trouble. The port at the rear of the unit was supposed to soften the advance, for pollution control reasons (it didn't do much of anything but ruin how the engine ran). Sources for the secondary vacuum varied greatly with model and year, and some came from the factory already capped off. Be sure that the base plate and vacuum arm are free and lubed up.

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