through transom exhaust

[Ian]

I know this has been covered before but I can't find the topic, I have a 21ft I/O that I want to install through transom exhaust on, it has a 350 with an alpha 1. First off, have any of you done this and if so what was involved? I know I'm going to have to pull the motor to get the y-pipe off, how hard is that? Also can I use the stock maniflod and risers (I'm not after an increase in horsepower, just looking for a little rumble) or can I bolt aftermarket risers on the stock manifolds. Has anyone payed a shop to do it, if so where and how much? Any advice is greatly appreciated

[Craig]

You only have to pull the motor a little bit up to get the y-pipe off and a block off plate on. I did this when I put on my IMCO's. The drive, 4 motor mount bolts, fuel lines and make sure the hoses and wires don't stretch, or unbolt them. You can do it with an engine hoist in a boat your size. A friend of mine ran a small block, he's on this board (Tee), ran stock manifolds with some aftermarket risers. Toughest thing is make sure you measure correctly on the transom before you take the ol' saw to it eek!
Craig

[wsm9808]

You could install the pipes that let you switch between through hull and through prop, but the kit for that starts at 650.00 bucks, and all the used ones I,ve seen on Ebay go for around 400.00.
Somone on this site told me you can just cap off the top of the Y pipes and run some hose for your through hulls. That way your Y is still there if you or the law gets tired of the noise, or if want to add the switchables later.

[HP350SC]

Ian:
I know this has been covered before but I can't find the topic, I have a 21ft I/O that I want to install through transom exhaust on, it has a 350 with an alpha 1. First off, have any of you done this and if so what was involved? I know I'm going to have to pull the motor to get the y-pipe off, how hard is that? Also can I use the stock maniflod and risers (I'm not after an increase in horsepower, just looking for a little rumble) or can I bolt aftermarket risers on the stock manifolds. Has anyone payed a shop to do it, if so where and how much? Any advice is greatly appreciated

[HP350SC]

HP350SC:
Ian:
I know this has been covered before but I can't find the topic, I have a 21ft I/O that I want to install through transom exhaust on, it has a 350 with an alpha 1. First off, have any of you done this and if so what was involved? I know I'm going to have to pull the motor to get the y-pipe off, how hard is that? Also can I use the stock maniflod and risers (I'm not after an increase in horsepower, just looking for a little rumble) or can I bolt aftermarket risers on the stock manifolds. Has anyone payed a shop to do it, if so where and how much? Any advice is greatly appreciated Whoops!Clicked wrong button.My friend and I both did thru-hull ourselves.Go buy the tips you want,get 2 or 3 feet of 4"hose and elbows from CP perf. and the right size hole saw.We pulled our motors anyway as it only takes an hour or two and its easier to slide the hose and elbows together.Get the rubber tipped METAL inside flappers not the crappy all rubber ones.I also run the external flap just to be safe.We both ran our exhaust under the waterline so they're quiet at the dock,and then get loud as you start to plane.Don't be scared,it's pretty easy once you get all the stuff together.Most transoms are about 3" thick,I think we drilled from the opposite side once the hole saw loaded up.

[01RENEGADE]

I had a shop do mine 600.00 picked up about 100 to 150 rpm sounds alot better too. I am also in the process of going from a 2 barrel carb to a 4 barrel carb and different intake. Dennis Moore is going to do a step by step article on the process.Should run in a magazine when its all done

[wsm9808]

I agree with Hp350sc that it is not all that hard to pull the motor, but if you are installing new tips, it is real easy to do the hose, just put the hose on the risers and slide the tip into the hole in the transom and into the hose at the same time and clamp it all down. Use two clamps on the tips if you put the tips below the water line- coastgaurd regulation. You dont want your boat to sink if they pop off.