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MB69
06-23-2010, 01:39 PM
I have a 1969 18 classic with a 350 Chevy block and a Merc Bravo 1 drive. It has the through-hub exhaust. I'm considering doing a through hull exhaust if it's not too much of a process. I did a search on here and found some information about the captain's call systems which would be nice but it looks like the installation if fairly labor intensive. I was hoping not to have to pull the drive or worse, the engine.

Is there any way to do a simple through-hull exhaust (possibly with a muffler/tip combo) without tearing the boat completely apart? I'm not looking for major power gains, just a more aggressive sound.

Thanks in advance!

axelkloehn
06-23-2010, 01:50 PM
It's an easy install w/o pulling engine or drive.

Keep the u-pipe at the drive, add the switchable t-pipes on top of the u on both sides, drill 3" or 4" holes in the transom at the height of the t-pipes, add the bellows and thru-hull-pipes (don't forget to seal them with 4200 or 5200!), do the electrics and your done. Make sure your thru-hull-pipes have rubber flaps or better internal flaps or both. As for the thru hull pipes you can choose mufflers of course.

The Hedgehog
06-23-2010, 02:46 PM
It's an easy install w/o pulling engine or drive.

Keep the u-pipe at the drive, add the switchable t-pipes on top of the u on both sides, drill 3" or 4" holes in the transom at the height of the t-pipes, add the bellows and thru-hull-pipes (don't forget to seal them with 4200 or 5200!), do the electrics and your done. Make sure your thru-hull-pipes have rubber flaps or better internal flaps or both. As for the thru hull pipes you can choose mufflers of course.

Pretty much.

Do NOT seal them with 5200. The guy that had my boat before me did that and it was not fun getting them off. If you ever want to change tips, blow out a flapper, re-rig something you will hate that. The factory uses a gasket.

You will want to seal the inside of the holes with epoxy before installing the tips. Let that cure and them install the tips. If for some reason you feel like you want to seal around the tips, use 4200 or less.

MB69
06-24-2010, 11:35 AM
Thanks for the advice guys. I'm a little bit of a novice so some of the terminoligy is foreign to me. I'm assuming 4200/5200 is referring to an adheasive/sealant.

It's been a while since I looked closely at the boat's engine compartment. (I have it stored about an hour from my house) The way I'm envisioning this is I will have a pipe that splits off of the back of the manifold. (Maybe that is the T you're referring to?) one end would connect to the drive and one to the through-hull pipe. I'm also assuming the electronics would be if I decide to go with a captain's call kind of system?

Can you suggest a good source for parts and additional installation assistance? Considering the size of the engine hatch, is this something I can do myself in a day? I'm pretty savvy when it comes to mechanical stuff but I do remember the engine being in pretty cramped quarters.

Thanks again for the help!

Just Say N20
06-24-2010, 02:46 PM
Do you need/want it to be quiet some of the time?

If not, then you could just by-pass the existing "Y" pipe all together, and run a hose from each exhaust riser directly to the thru-hull.

4200 and 5200 are 3M marine sealants. 5200 is wicked strong, and will actually cause the fiberglass to delaminate rather than break through the 5200. Anything sealed with it should be considered permanent.

MB69
06-24-2010, 09:02 PM
I don't see any reason I would ever need it to be as quiet as it is now. I want a deep, throaty sound but I want to smooth it out a little which is why I want to go with mufflers. Excuse the comparison, but maybe something like a 2-chamber flowmaster would sound without cats. My brother has a 09 Master Craft X-Star with the 383 6L motor in it and it sounds perfect. I understand that my engine doesn't compare to the 400+ HP EFI motor in the MC but I'd like to get as close as I can. That thing sounds absolutely angry.

So, would I cap off where the original pipes connect to the drive? Any suggestions on the muffler/tips based on the sound I described? Does all of the water from the cooling system exit through the exhaust pipes if I do it this way? Am I going to notice any performance change by doing this?

Thanks again for all of the help!

3rdDonzi
06-25-2010, 08:29 AM
My 18C has the 350 mag alpha setup. Straight through hull with no Capt's choice. I wanted it to be just a little quieter but still have a throaty sound so I installed Eddies Marine slip ins for under $80. Unbelieveable difference. Sounds awsome, just a little louder than my Mastercreft at the dock and about the same when underway. Also if you want it loud again, two small bolts and they are out in seconds.
3D

MB69
06-30-2010, 11:48 PM
Okay, so I called Eddie Marine and got some interesting info. They claim that I would have to pull the engine to bypass the factory Y-Pipe becuase because of there the Y-pipe connects to the drive. They said some people cap the Y-pipe but that no one made a part to do it because of the liability. If the cap came off the boat could flood...

They recommended their captain's choice which connects to the existing Y-pipe and then also has to output for through transom. Any thoughts on this?

The Hedgehog
07-01-2010, 09:29 AM
Okay, so I called Eddie Marine and got some interesting info. They claim that I would have to pull the engine to bypass the factory Y-Pipe becuase because of there the Y-pipe connects to the drive. They said some people cap the Y-pipe but that no one made a part to do it because of the liability. If the cap came off the boat could flood...

They recommended their captain's choice which connects to the existing Y-pipe and then also has to output for through transom. Any thoughts on this?

Actually I think that Eddie Marine is full of BS in this situation. People cap Ypipes all the time and it works. The top of the Y-pipe in most cases is above the waterline anyway. I removed my y-pipe on a boat because the Y-pipe connection leaked and that was when I had captains choice. Following that logic one could say that captains choice can and will sink your boat.

Yes, removing the y-pipe is better. They make a block off plate for that. I bet that EMI would be glad to sell one to you. Guess what. They are known to leak and sink boats too. So will anything that plugs a hole below the waterline.

Cheap and easy route, cap the Y and go through the transom. I would do that and see if you even want captain's choice. If you don't, the next time you pull the engine you can remove the Y and cap it with a block off plate. If you want a selectable exhaust, wait to look around on E-bay. There is alway someone selling a system. All you will need is the selectors and actuators at that point.

upnorth
07-02-2010, 06:40 PM
Aquapower makes some very nice exhaust products. They have some slip-ons that really kill noise if you want to be real loud some days and not others. If your anywhere near minneapolis MN I would suggest Valleymotorsports. Excellent work, and some of the most knowlageable boat people around!