Re: head gaskets
Depends upon which 50 and 55 you are talking about. If the 55 is a single carb 55 from the 35, 45, 50, 55 small bore (3.187) series, then the head gasket is the same. The horsepower difference comes from different port timing, compression ratio, and an added spacer in the exhaust chest for less backpressure.
If the 55 is a two carb 55 from the 55, 60, 65 big bore (3.375) series, then everything is completely different. This series engines also usually have the hood latches on the sides rather than front and back like the smaller series. It is also a superior engine design which makes the other 55 look like a sick puppy.
