old style log exhaust to king cobra with riser

cardoctorlv31

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Jan 22, 2011
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hello everyone i've been a silent member and learned a lot by reading , this is a awesome forum !

I purchased a 74 reinell cabin cruiser with a chevy 350 225 electricshift for a great price knowing it needed a motor swap due to cracked block . I rebuilt a sbc 305 out of a 77 chevy 2500 pick up put marine gaskets freeze plugys and cam , eledrbrock intake and carb also changed over to Hei distributor . engine runs great . I rebuilt 225 outdrive new seals and shift magnets , I took out on lake 3 times without a problem , 4th trip water in oil , which turned out to be leaking exhaust manifold (old log style) I've purchased a used set of king cobra exhaust manifolds they come with a y adapter .
My question is can I reduce the outlet of the manifolds and have them exit the transom ports like the log style did , I have already purchased reducer coupling's to attach to them ? thanks
 

Redrig

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Oct 13, 2009
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Isnt there a slight bend between the riser and transom port ? there is on my stringer anyways .

if its a straight shot between the 2 points , then sure just add a reducer probaby a 3.5 to 3.

If it bends though you may have problems because the length is so short and that exhaust hose is some rigid stuff.
 

cardoctorlv31

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Jan 22, 2011
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thanks REDRIG I actually got connected had to reduce 3.5 to 2 1/4 I'm trying to figure out how to connect transome hoses and t-stat to risers now ? old log style there is 1 hose on rear of manifold's to transom and in front each have 2 hoses to t-stat . king cobra at rear of manifolds is a rubber plug and front single attachment . Not sure if I can unplug and connect transom to rear then block off 2 on t-stat and other 2 on t-stat to front of manifold's ? I don't want to hydro lock or damage trying hope someone has tried first can let me no if it's going to work or how . thanks
 

Redrig

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I converted to center risers from my old logs (Fords though ) and I only used the inlet at the front of the manifold and plugged all the other . There are inlets at the risers but Iam not using them

here is a link to mine , again they are fords but there may be some useful info in there for you .

http://forums.iboats.com/forum/engin...onversion-ford
 
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cardoctorlv31

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Jan 22, 2011
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thank you !! REDRIG THATS WHAT I WANTED TO SEE ! Question looks like the rear of your manifolds don't have the nipples that are blocked off on mine , your t-stat has 3 hoses one going towards rear of motor is that going to transom water inlet ? my transom has to inlets on it did you block one ? THANKS SO MUCH didn't think I would get such a quick response nor one from someone who's done this Thanks again
 

cardoctorlv31

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Jan 22, 2011
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REDRIG My setup only used the impeller in outdrive and regular water pump like on car engine , do you have a seawater pump or something , wondering if impeller will push enough water due to having riser my logs were straight with a curve drop .
 

Redrig

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Oct 13, 2009
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Mine is raw water cooled .

You should have 2 hoses coming off of your thermostat housing and going into each of your log manifolds . The hose coming from the transom is the water that is being pulled up from the impeller to the Tstat housing , so the source of all cooling is on that line. Then its distributed to the water pump / engine and to manifolds for cooling (via the hoses at the front of each manifold)

The nipple thing at the rear is for draining the manifolds for winter , at least on mine .
 

VE8EV

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Make sure your replacements have the proper riser gaskets. With raw water cooling the water goes into the manifold at one spot, it fills the manifold, goes up the riser, and dumps out with the exhaust. If your new manifolds and risers used to be on a closed cooling system then they'll have a blocking gasket between the manifold and the riser. Easy to check, just make sure water comes out the exhaust when you pump it into the manifold.
 

cardoctorlv31

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Jan 22, 2011
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thank you ve8ev yes water exits exhaust , REDRIG on my transom there is 2 hose attachments I believe there both inlets looking at your picture its dark I think I only see one , should I tee the 2 I have then to the tstat or plug off one of them ? Also my t stat housing is the one with 4 hose 2 on each side of it think I need to get the one like yours ?
 

Redrig

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Post up some pics if you can.

But yeah , if you have 2 hoses feeding each manifold I would just tee them into one line that enters the front of the new manifold .

Anyway you do it , just make sure the manifold only gets a little warm with the engine on . If they are getting hot and not getting enough water , you will cook your exhaust hose
 
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