Any problems with cutting the exhaust Y-pipe?

[greg82255]

Hello,

I had a 1986 Merc 260/Alpha One, but that block is currently at the machine shop and will be the base for my 383 build over the winter (see thread in the Non-Repair I/O forum). I am looking at different performance exhaust systems to use with the new 383, along with the custom silent choice that I made, and it doesn't look like it's going to work with the current setup of my Y-pipe (or any other Y-pipe that I've looked at online). The one in my boat (well, in the garage at the moment) is a circular pipe, 3-inch diameter. Lots of people in these forums say that getting the exhaust to fit right is just a trial and error process. I was thinking I could cut the Y-pipe about half way between the opening on the transom assembly and the top of the pipe on each side, and use either some flexible exhaust hose, or a custom-bent pipe in its place. I'd also move the shutters down to where I end up cutting it. Has anyone ever done this before, or am I missing something that would make this impossible to do?

 

[Brentathon]

Re: Any problems with cutting the exhaust Y-pipe?

Interesting.
Where's the waterline going to be? Does the Y-pipe connection point have to be fully watertight (i.e. below waterline)?
Are the shutters going to be below waterline, then?
Maybe just a few things to think about...

 

[cr2k]

Re: Any problems with cutting the exhaust Y-pipe?

Y-pipe connection points DO have to be water tight. I don't see any problem as long as it's sealed tight. Flappers would be best used above the water line.

 

[greg82255]

Re: Any problems with cutting the exhaust Y-pipe?

I agree that it absolutely needs to be water tight, as it will probably be very close to or below the waterline. I'll see if I can get a set of 3" internal flappers and install them inside diverters I have. What would be the best way to seal the connection below the water line? is 3M 4200 heat resistant? or is there something better that would work?