I finished tearing down (the bad one) and cutting for the most part on it and found it was marked 16cc E under the exhaust port. Obviously one of the older 16cc units. But I will weigh it bare anyway just for courosity reasons. I was hoping to use it as a pattern for future components. I have a few more of these Echo and Mac weedies so I guess I will check them out for size. I noticed some have rounded design fins and some are square. Does that mean anything as far as size of the engine? Here is what it looks like at the moment.