I'm in the process of pulling the heads on my 420 sel, I have everything off and I'm trying to get the heads off the block. Any tricks to remove them. I have at least 2 bent valves from the timing chain rails breaking and the chain jumped 3 teeth on the left head and 5 on the right. Also I think I will pull the timing cover off to replace the chain because there are rail chunks down in the front, cover any good tips for that. thanks Lewis.