On my 340 I followed the smooth surface,loosen & retourqe,& rivet clearance. I had a leak on start up. I used some Unnamed Autozone sealer. 3 years ago street & race, high engine temps in traffic, no water loss. I agree the Moroso sealer is the best. I have had it seal 6" long crack in the side of my 440 block for over 3 seasons of racing. no drips, no water loss. Doug
