How much vacuum?

[lonewolf]

For an 80-83SC-cis.

Does anyone have the specs on how much vaccum is pulled on the decel,retard and vac advance lines?
I know the decel and retard lines drop off when butterfly opens and advance line increases but to what numbers .

thanks.

[T77911S]

go buy a hand vacuum pump. you can check it yourself plus it comes in handy. i use mine quite a bit. in fact, i used it friday and it found that my wastegate on my 930 is bad. its also a good idea to check the vac line to the brake booster.

[Bob Kontak]

I don't remember seeing specific vacuum readings but the timing retard is intake manifold vacuum. The timing advance is ported vacuum. If you put your finger on the retard hose you will feel vacuum at idle but not with the advance hose. I am not sure exactly what "ported" means but it delivers vacuum to the advance unit on the side of the dist after the rpm's start to rise to work in conjunction with he mechanical weights.

Search for "CIS Primer" and it has vacuum diagrams. Here it is. CIS Primer for the Porsche 911

Pretty sure the decel valve is intake manifold vacuum. I negates some of the extremely high vacuum created by lifting your foot off the accelerator when the engine is spinning at high RPM.

[kodioneill]

18hg at idle is normal