[Cobra 29]

The vacuum at manifold and at the carb (ported) provides a good reading either way. No restrictions. When increasing the throttle the ported source will begin to advance and provide advance from none to max via the vacuum module. Under the same situation manifold vacuum (and advance from the module) will move in the opposite way; start higher and then become zero or near zero at WOT. It was my impression the engine rev'ed easier (from slight throttle to near full throttle) with the advance "map" provided by the ported source.

I have had more time connected to ported vacuum so maybe when I switch to manifold it will provide the same crisp throttle response I think I am getting with the ported source.

At any rate the bigger question is what do timing experts think of 10 initial, 25 in the distributor and the vacuum limited to 8 and connected to direct manifold vacuum thus providing approximately 18 degrees at idle? And having decreasing advance from the vacuum module as the throttle is moved toward WOT?