Adjusted Valves, now it smokes

The engine is a 318 Poly, unsure of year. I was having problems with the engine stalling after start, and was advised to adjust the valves. I did so using a chart someone had provided, and everything went great, but it didn't stop the stalling problem. I later found someone had previously installed an electric fuel pump and tucked it way up in the frame unseen. I bypassed it, and the engine now runs properly, and yes, a lot better than it did before, after adjusting the valves.
The problem I'm having is, the last few times I've driven it, sometimes it spews out a whole lot of white smoke out the exhaust, but it doesn't smell like oil or anything. It just looks like condensation almost. It never did this before I adjusted the valves, could I have adjusted them a bit too much? Could it also be that it sat, without being run, for a few months before I did anything to it? When it smokes, it's only for a couple seconds, but its a LOT of smoke pouring out the back. I have a 4bbl manifold for it that I would like to put on, but there's no point if its in need of a rebuild.
Any advice is appreciated, thanks.