Throw a couple bottles of Iso-Heet in the tank and call it a day. Our standards are pretty tight in AZ and I've never had one fail when using Iso-Heet in the tank. 90+% Isopropyl Alcohol will work just as well. I was able to get my Demon through with a 284* 484" cam in my 340. It ran like crap, but I was able to choke it enough to get it through.