I've done a few but never had to pull the grille or bumper....maybe if you're changing the cam you would. Set the timing at TDC, pull the radiator, fan, outer crank pulley (if it has one), balancer (with a proper puller...don't pry on the outer ring!) front pan bolts and T.C.bolts, and cam sprocket bolt. Spray WD-40 on the crank sprocket and work it off with a pry bar or puller along with the cam sprocket and chain. Install the new set, spin the engine around by hand a couple of revolutions, Degree it, and reinstall everything.