360 timing advance problems
[1] If connected to pass side, it is PORTED [ PVA ].
[2] This post is another great example of ignorance getting in the way of FACTS; blaming MVA when it is not to blame: because we know NOTHING about the numbers: was it in fact connected to MVA? Where was the initial timing set? If it was set to 20*, MVA might do little if anything on a mild engine. How much did VA add? Some cans can add 30*. Etc.
[3] If in fact it was connected to PVA, then there is a tuning problem because there should be vacuum on the PVA port at idle. Cause of THAT problem needs to be addressed first.
MVA works PERFECTLY as advertised when it is set up correctly, period.