The Cape Cod Crusader

[cdavisdb]

Ditto on the risers.

[FishStretcher]

I will need education on this one. If there is a good website for how this works, or you want to type it out, I would really appreciate it.
The Seloc manual covers every configuration in the book, and a 5.7 with fresh water cooling and partly (?) cooled exhaust is something I know nothing about. But it looks like I need another riser and a harder bend for the exhaust, you say? There sure looks like there is room I was wondering why the engine cover was so tall. I have to do some other engine things, so the more I know, the better. I have a 1 ton chainfall, so I can move the engine if I have to. And a mobile cherry picker good fro 500lb at that reach.

I already warmed up the credit card late last night, so now I need to see what my unintentional expenses are.

[Blue_Heron]

Originally Posted by FishStretcher

I will need education on this one. If there is a good website for how this works, or you want to type it out, I would really appreciate it.

I dragged my installation manual out of the shop to check the requirements. The manual is for Mercruiser gasoline sterndrive models and includes the 350 Mag MPI in both Alpha and Bravo configurations with Serial number OM668000 and above. Do yourself a favor and throw out that Seloc manual and get the factory service manual. You'll need two manuals, one for engine, one for Bravo drive.

Anyway, the installation manual says the minimum exhaust elbow height is 13" (33.0 cm) above the static waterline with the boat fully loaded. That means full tankage, gear and crew. My fully loaded static waterline is around the middle of the scuppers unless everyone moves to the back of the boat. That puts it an inch or two below the deck. Which would make minimum elbow height around 11 or 12 inches above the deck to the top surface of the elbow casting. I just checked mine and it's at 11 3/4".

If you increase your exhaust elbow height, in addition to the riser extensions, you'll need longer intermediate elbows. Those are the ones that connect the riser elbow to the Y pipe. They will have a slightly sharper angle than the shorter ones.

Something else you might want to check:

From page 19 of the installation manual - IMPORTANT: Bravo closed cooled models require a through the hull or through the transom pickup in addition to the sterndrive water inlets in order to meet the minimum flow specifications.

So there should be a Y fitting on the engine cooling hose behind the seawater pump on the starbord side of the engine. The Y fitting should have one hose fed from the Bravo transom assembly, and another fed from a through hull.

Dave

[FishStretcher]

Ouch. Riser kirs for a dry joint exhaust are $450?!? They should be titanium for that price.

[cdavisdb]

For mine, volvo makes hugely expensive, one piece hi risers, but you can buy extenders for the existing risers, after market and much less expensive.

[BigLew]

This is a good thread, a lot of key information. Not enough height and we may be costing ourselves needless manifolds and risers, not to mention possible (likely) engine damage of not having sufficient height!

Thank you! Please continue.

[gofastsandman]

Don`t chop the throttle and let them idle for 2 minnows before shutdown.

[Blue_Heron]

More on the topic:

http://www.perfprotech.com/blog/unca...d-and-checking

Dave

[FishStretcher]

This is all great stuff.

Mine does have a thru hull pickup and a Y pipe to the gimbal/lower unit for raw sea water pickup. I was confused by that, now it makes sense.

I bet my exhaust risers are not much above the deck, judging by the pics. the scum line on the boat is perhaps 4-5" below the scuppers, so fully loaded, I can see the waterline being close to the scuppers.

I do have a post 2002 engine, , and 0W0..... serial number- so with the dry joint, all the riser extension kits are >$400 that I can find. I looked at eBasic Power, Osco, Mercury... Unless I am dong something wrong?

The older extensions are 1/2-1/3 the price. If I need the expensive dry joint extensions, I need them. But it looks like a lot of $$$ for a few bolts, gaskets and lumps of cast iron. Plus, as you pointed out, the intermediate elbows.

I will take measurements and see how far off it is. Is there a known downside to more than 13" above waterline? Because the pricing for a 3" extension and 6" is about identical. So I might wind up with 15". I guess if 13" is the minimum, then a bit more is OK.

[FishStretcher]

Pictures of the (scum) waterline before the repower. Blue Heron passed these along.