I have been looking into finding more information on the 440 in my Plymouth and can't find all whats inside but have found out that it was rebuilt and done .30 over and was told it has a mild cam and also has closed chamber heads, just wondering if someone can tell me about them, fairly sure it has pretty high compression, guessing at least 11:1 or maybe a little more and have had the problem with knocking once the engine gets lots of heat under the hood and has been driven for anymore then about 20 miles, coolant temp is fine but just a lot of internal heat and with todays crappy gas have to use premium and octane boost to help out so decided to get a Snow water methanol injection kit for it, will post more once i find out how well this works. So if anyone can tell me what exactly closed chamber heads are and what other heads there are out there and are these heads giving me a higher compression also, thanks for any help.
