Hello, me again.

The car still smells like an oil rig, but briefly set the idle mix with a ColourTune just to get it a little leaner. Seems a little better, idle is too high and once it's warm, it surges.

Guess that's cause it's too lean bottom end. Also, static timing doesn't help. But, reading around it seems that there's two schools of thought on this..

Vacuum advance port has to be atmosphere side of the throttle plates.

Also, was this not done by Mikey too? Where he tapped into the carbs, rather than the mani?

So, what's right? I thought, under no load (foot off), the mani had vacuum, and once your foot gets dumped, vacuum goes to zero (or open to atmos)?

So, if the tapin is on the mani then surely you get loads of advance when your foot is off, and none when it's on?

Thoughts?

My Vac advance is post butterfly, mickey drilled the water casting for his feed which is also post butterfly.

Ideally you use a carb petrol filter as a collector to clear up the signal.

Yeah, i know about the filter, and to use all 4 runners, but wouldn't post butteryfly mean the advance is the wrong way round?

You want more advanced with less load.

Less vacuum = less advanced.

More throttle = less vacuum

Thank you Nick!

See 'How Vacuum is Used' in this

http://www.corvetteclub.org.uk/files/downl...acuum_ports.pdf