Help with timing issue

[DoubleL]

Thanks for your input in advance guys.
I have a new HEI with the coil in the cap. It has full 12 volt power.
I set the timing at 4 degrees advanced with vac advance plugged but when I reconnected it the timing jumped and advanced past the "A" setting on the indicator. It probably advanced 16-18 degrees when I plugged it in. I ended up lowering the timing to "0" so it wouldn't advance so much. The truck idles and revs great but totally falls on it's face going up hills.

What should I set the initial timing to? What should it jump to when I hook up the advance. I have the advance hooked to a port on the manifold is this right?

Any advice would be appreciated. Also it has been verified that the timing mark is correct at TDC.
Thanks guys!!!