This is driving me nuts. I have read a few places that the CTO contols the vacum advance. Then, when looking at this diagram, I see that its going to what looks like manifold vacum. Is that thing with the large M the distributer vacum advance, and is that a manifold vacum port. I'm running extremely rich, enough to burn up the cat. I'm trying to eliminate any timing issues before putting in a fuel regulator and cuting back the air/fuel mixture on the Weber. When you guys did the nutter bypass and the MC2100 conversions what did you do with the EGR valve. My EGR is currently plugged.

diagram. Red arrow marks the spot

My manual also shows this exact diagram but my new howell kit states that the vacum advance is controled by the CTO. This obviously is not going to the CTO.

that is the intake manifold vacuum at the T in the brass fitting where the brake booster vacuum line is attached.

doing a lot more searching I found that yes that is the manifold being used for the vacum advance on the distributer. But it also goes to the 10-4 HG switch that act like a TPS. From what I have read you want the ported CTO vacum if you did the MC2100 or weber carb conversion. Without those switches the manifold vacum is too high at idle and the consensus is go with the Poted VACUUM.

If anyone has anything else to add or any other insight please let us know.