hey guys, thanks for the replies. So it seems like rust is the main issue (isn't it always!?) I own a 64 lincoln continental at the moment and one of its weaknesses was the nylon-coated timing gear lincoln used for noise reduction. Unfortunately, with age, the nylon would strip away and collect in the oil pan, starving the engine of oil. I purchased a book called, <span style="font-style: italic">Buick Riviera Performance Portfolio</span> by RM Clarke in it an article state, " An interesting internal change that applies to both the 410 and 425 engine is a cast aluminum camshaft sprocket which incorporates nylon-plastic covered tooth surfaces." This article was pertaining to a 63 riviera, but I am wondering if this was an area of concern. thanks.