When plumbing the vacuum line from the distributor to a manifold vacuum source, does it matter if I use an existing port on the back of my RPM intake or do I need to use the smaller manifold port on the carb?

I thought that I may have read somewhere that the intake port may not have as strong of a signal as the port on the carb due to it's larger orifice size.

Thanks

Probably no measurable difference due to the orafice size as its dead head (no flow). However, on a hot cam it would seem possible that lower rpm vacuum might not be as steady in a runner. If you see lots of evidence of reversion (carbon up into the intake) then that would be a clue that further from the valve would be smoother.

OTH if the cam is that hot, its unlikely the engine will really want manifold sourced vac advance...