1972 FASTWIN EVINRUDE 18 hp Pistons and piston rings

[redbrass_ca]

Hi members

I am looking for piston rings sets

I have a question relating piston and piston ring for a fastwin 18 hp (1972) From what I read so far it appears the 18 HP engine was manufactured from the late 50's to the mid seventies. I have tore down the engine and both piston 1 and 2 have cast numbers which is 317564. I have a 1972 exploded diagrams of the outboard and it lists reference number 385338 for the Standard piston and 385349 for the piston ring set. When I look carefully at my pistons it has two ring grooves. They are both different . The top piston groove is tapered and is 2.3 mm wide. The bottom piston groove is 1.62 mm wide and square The Piston is 63.22 mm in diameter . Could anyone help me in locating the proper part numbers? Is there aftermarket rings for these pistons? Any suggestions would be appreciated

Terry

 

[F_R]

The pistons & rings were changed a couple of times through the years. Best advice I can give is use the correct parts book to find the original numbers, then a dealer can look in his books and find the latest number that replaces them. But of course if you are figuring on replacing only the rings, you have to get the correct ones for the pistons that are in there. The newest style has two rings with a tapered top ring. DO NOT get any bright ideas and put 20 or 25hp pistons in it. There's more to it than that. Parts list is at http://shop.evinrude.com/