Timing advice

So after educating myself on all the useful timing articles I could find on the net and buying an advance timing light(FINALLY) I just got back in from setting the timing on my 1971 Demon 318 with all the bolt-ons and mild cam. Daily driver.

I checked where it was set first and then I realized that the vacuum advance was plugged into MANIFOLD VACUUM at the base of the Holley carb. I checked the timing and it turned out to be 25 at idle, if I understand correctly. (The timing light set at 25 had the timing mark right at zero).

I disconnected it and plugged the line and set the timing to 5 BTDC. Reconnected the distributer to the PORT VACUUM and the car runs good, seems to idle better now too. Only thing is now that I have it set, I'm getting a slight but constant puff of white smoke from the left tailpipe that I don't remember being there before. Any ideas what this might be?

I'll be checking the vacuum as well as soon as I get my vacuum gauge in the mail probably today or tomorrow.