Pagoda SL Group

W113 Pagoda SL Group => Drive train, fuel, suspension, steering & brakes => Topic started by: KenBourque on October 22, 2011, 02:04:57

Title: Vacuum advance
Post by: KenBourque on October 22, 2011, 02:04:57

On the 1970 28SL, at 2400RPM the two-way valve closes and eliminates the vacuum retard which was in effect at lower RPM's.  Does anyone know just how much advance is introduced at this point?  Should I be able to perceive a slight surge in power?

Title: Re: Vacuum advance
Post by: Benz Dr. on October 22, 2011, 03:30:26

The mechanical portion is about 10 degrees and the vacuum is about 20 degrees. The system is set up so that the vacuum cuts in just as the mechanical portion is finishing its advance. It's more or less seamless so you really won't feel it.

If the vacuum portion isn't working, and they often aren't, the engine will lack power and use a lot more fuel.

Title: Re: Vacuum advance
Post by: jeffc280sl on October 22, 2011, 16:55:35

The fact that your two way valve operates as it does indicates  the emission control system or at least part of it is operational.  There are two relay boxes located on the inner fender near the battery that are the brains of the system.