Possible to use Volvo exhaust on mercruiser

[cruiser83]

Thinking about swapping a sbc 383 into my boat in distant future. The motor has tall valve cover to clear girdles and roller rockers. I did some research and seen that Volvo has alot of spaceing for exhaust ports. I'm thinking they will clear with out spacers. Would i beable to block off some ports on the mercruiser thermostat houseing or do I gotta buy a Volvo one? Or does it effect the entire cooling system and won't work with out swapping go entire Volvo cooling system?

 

[achris]

You'll also have a problem with matching up the outlet of the manifold/elbow to the y-pipe.

 

[Scott Danforth]

Is this the 383 from your surburban in this post? https://forums.iboats.com/forum/eng...king-noise-under-load?p=10831246#post10831246

if so, as I mentioned in that thread, if your motor wasnt built as a boat motor, dont do it.

here are the reasons I wouldnt use your existing motor:

compression is too high
most likely cam is wrong for marine use
most likely a 2-piece RMS

and this is the same hull that you still need to restore and fix the 6 foot long crack in the keel prior to worrying about the motor

now back to your question on VP manifold

yes, it will physically bolt to the heads along with any other manifold. however it wont connect up to your existing Y-pipe, etc.

My recommendation, if you want to build a marine 383, do it. however the motor must be planned to be a marine motor from the beginning. 9.4:1 ratio, proper quench, some mild porting, and no more than 270 degrees of duration with a roller cam (268 with a flat tappet) unless you go with jacketed dry exhaust (and on a small block, that will equal the cost of the motor)

 

[cruiser83]

Yes same motor from my suburban, and I've talked to an engine builder, and a marine tech and both said the cam will work and I shouldnt have any problems after seeing the motor build sheet. Besides the fact that maybe I gotta switch freeze plugs. And I'll end up useing a thru transom exhaust. I going to take the hull to a shop to see what they say and I also got my eye out for another hull that will use all my parts.

 

[cruiser83]

But like I said this is distant future. Im just trying to figure out what works with tall valve covers. I might still change the cam in the motor too. And have it gone through. I just couldn't find anything about the Volvo manifolds working with tall valve covers and I really would like to know if someone else has done it, before I spend 1500-2000$ on some manifolds. Or buy Volvo's for 600 or find some used ones.

 

[Scott Danforth]

or buy custom valve covers for about $150

Not sure why you need tall VC's on an SBC running studs and roller rockers? they fit under the stock stamped covers just fine. I ran them in my SBC in the boat for years and many hot-rods.

If you are running a cam that requires shaft mounted rockers, then definitely the wrong cam for a boat with wet exhaust.

I would post your cam card here along with your engine build sheet. reversion is an engine killer, and the wrong cam will pull exhaust back into the cylinders.

with the wrong cam, just standard thru-hulls wont cut it, needs to be jacketed dry-exhaust thru-hulls where the discharge water mixes with the exhaust about 26-30" from the collector on the manifold (about 4" outside the boat in most cases) (read this as custom built for your boat).

 

[cruiser83]

I trired to run stamped chrome ones before with a different set and they rubbed. I'll check tho. There 1.6 rocksrs if that makes a difference? There pretty big. And have girdles. But I noticed the back of my block/manifolds on the vortec. Seem to seep and are dry around the risers. So makes me believe there might be a crack.... I gotta pull them and check them out. FML man this thing is nothing but bad news.....