YOu won’t know until you boat test it, but I’ve not heard of an evinrude “losing power” because of a leaky pressure tank. It may get starved for fuel and quit on you, but they usually don’t keep running and perform like a lesser motor because there’s pressure escaping.
FWIW I don’t think you’ve ruined your flywheel, but do get the coil alignment taken care of. in another FWIW, I’ve never used on of those coil setting rings myself, because I don’t have one. I do have an eye and a feel for setting up things without tools and getting it so close that normally the engines always run without having to fine tune things. If the ring isn’t working for you, start going by feel and shift your coil positions so they ain’t rubbing on the flywheel and still give your ignition energy when it needs it.
I have a ’57 Evinrude Fastwin as well. It was in use when I got it but they said it was “getting tired” and was losing power. They’re description of the issues sounded like it was only running on one cylinder. As soon as I got the motor, I could tell that the upper crankshaft oil seal was done. A telltale oil and sludge buildup on the port side of the exhaust housing gave it away. With a new oil seal installed, the mag plate replaced because the old one was a bit sloppy (sound familiar?) and the fuel system gone through, it is now one of my most dependable classic outboards and I put a considerable amount of hours on it last summer on Lake St. Clair.
So yeah, look into that magneto plate, it shouldn’t be wobbling around, it needs to be stable when it pivots…otherwise your points timing and coil alignment are gonna be nearly impossible to set correctly.
Hope this helps.
Best
PM T2
He's livin' in his own private Idaho..... I hope to go out quietly in my sleep, like my grand-dad did..... and not screaming, like the passengers in his car...
