Snip the more i think about it, the more i'm convinced that all inline sixes are internally balanced by their very nature. i haven't yet heard of one that isn't. Snip Not that this is one of the things that I keep track of as a hobbiest, so I could not comment standpoint of knowledge, it is my understanding that internal or external balance is a decision made by the designer. Even the legendary Chevy small block which is internal balanced as I understand, the 400 cu in version of it is externally balanced leaving one to do some extra work when installing a 400 crank in a 350 to make the popular stroker 383 due to the external balance configuration of the 400 crank, as I understand it. How some ever it was the increasingly popular use of building and installing I-6 engines in some of early 1900 automobiles that lead to the invention and refinement of the design of the Harmonic Balancer due to the annoying habit of those engines to break crank shafts with out provocation. A problem that still prevails today. I am not sure how much balance plays a roll in that action, but my gut feeling is that the inherent balance design of an I-6 engine is pretty much an urban legend leaving the final decision to the method back in to the hands of the designer. In any case if I were to work on an I-6 engine other than my trusty 232 or 258 , the method of the engine being balanced would be about number 1 on my need to know and had better find out quick list of things to do. If memory serves me correctly, and as a certified old guy now it is allowed that my memory can be faulty but still infallible, my Grandfather bought a brand new 1956 or 7 Rambler, 3 tone purple and mauve paint with matching interior off of a show room flow and had the crank shaft break in two on it with in a few thousand miles. Boy those were the days, three tone paint and a matching vinyl interior. A far cry from spending mega-bucks for a monotone Buick with a gray mouse fur interior that you can do today. Lets hear it for another better idea! A 4 door Mustang PPPPFFFFFTTTTTT! Zoom Zoom John _______________________________________________ AMC-List mailing list AMC-List@xxxxxxxxxxxx http://www.amc-list.com/mailman/listinfo/amc-list or go to http://www.amc-list.com