1987-242SS454

I have a 1987 242 with the 454. I want to add thru-hull exhaust . What are my options for this boat? I know that when it came from the factory it went through to bolt on fiberglass swim platform. Is the factory set up still available. Does anyone know a salvage place that I might be able to find the set up? Is there any aftemarket kits? Thanks for any help you can give.
Brian

ThirdBird

Are you saying that the Silent Thunder platform is not on your boat? Did not come with it? If you don't have the platform, it will be very difficult to find one. Matter of much searching. Guys here on this board are your best bet.

1987-242SS454

Yes , I do not have the silent thunder platform-it does not have the cut outs. I think I need to swap out the whole platform, if I can find one...that is the problem

ThirdBird

So, you've basically got straight through hull exhaust with some sort of aftermarket platform?? Got tips? Any pics?

1987-242SS454

No, I have no thru-hull, it goes through the drive now. I want to add thru hull, but do not know how to make it work with a non-silent thunder swim platform

ThirdBird

Ohhhhhh, now I understand!

Believe it or not, the Silent Thunder Exhaust platform was actually an option, at least back in the '80s it was. Almost all Formulas were ordered with it. Obviously, yours is one that was not ordered that way.

So, as I stated above, finding a Silent Thunder platform is probably not an option. It's relatively simple to run your exhaust through the transom though. The hardest part is to figure the height. Silent Thunder exhaust holes were cut quite high on the transom, you could go a bit lower than that. Once you locate the holes its just a matter of doing a nice job cutting the holes. That will be a bit tricky as the transom is pretty thick. Then you either run straight tips or mufflers (cha-ching for the mufflers). Buy some marine exhaust hose and run it from the manifold risers to the tips. Stuff is very stiff, you won't be able to bend it into place.

You'll also have to block off the old exhaust outlet on the inside of the drive. There is a Mercruiser blank flange and gasket for this purpose, but I think you have to pull the engine to install it (not sure on that).

Hope all that helps some, there are others here that can direct you more better than me. Good luck.

1987-242SS454

Thanks for all of the info. I would like to get the whole platform. If I went through the hull with tips I think I would have to go through the platform up high, but then the exhaust would dump over the platform and possibly discolor it? Or I could go below the platform in the middle, but that would be awfully close to the waterline. Theblank plate would be nice but I do not want to pull the motor out again! Thanks again.

ThirdBird

If you go with through-hulls, you'll have to blank off the through-prop setup or your gonna sink the boat.

1987-242SS454

good point!

masi242

Welcome to board

The first thing you may want to do is pull the platform off and see if you run the exhaust thru it like the factory did. It will require a little cutting to do it like factory IF the inside is the same, my guess it would be close.

Thirdbird has a good idea run it straight under the platform or thru the platform.

Look through some of the old threads I have on on 242 exhaust a little to much work Remember you will get no performance benifit from this but it will sound nice

good luck

mark