A new timing chain elongates more than an old one per mile traveled... the Factory shop manual makes the distinction at 20,000 ( something )..... so you might need to check your timing again... and a new chain wears even more being placed on old sprockets...White smoke is unusual around here.... the last time I saw it was on a Ford which was sucking trans fluid out of the auto trans....So I would caution you to watch your coolant level... you may be producing steam ....