Dual exhaust for 283 in a 55' Sportsman

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Dual exhaust for 283 in a 55' Sportsman

Postby parksman » Wed Jun 28, 2017 12:41 pm

I have been rewiring my 1955 sportsman with a 283 engine. With everything torn apart it seems like a good time to add the duel exhaust I had been planning at some point. I am guessing that the single exhaust that is on it was with the original six cylinder engine. It currently has a 2 1/2 inch single exhaust. I have two new 2 inch exhaust rings and access to new 2 inch copper pipe. Is a dual exhaust system with 2 inch pipe sufficient for that engine? It is a stock 283 and is not a high-performance engine. It is a user boat and not for shows.

Any input you could provide would be greatly appreciated!
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Re: Dual exhaust for 283 in a 55' Sportsman

Postby jim g » Wed Jun 28, 2017 7:11 pm

From the factory Chris Crafts with 283's with dual pipes would be 2 1/2". 283's with a single exhaust outlet would be two 2 1/2" hose into a wye from the wye to exit through the transom would be 3 1/2".
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Re: Dual exhaust for 283 in a 55' Sportsman

Postby parksman » Thu Jun 29, 2017 3:03 pm

In that case I will need to buy some copper exhaust pipe. Would anyone know if it needs to be type K, type L, or type M? I can buy it locally but I'm not sure which type it needs to be.
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Re: Dual exhaust for 283 in a 55' Sportsman

Postby Don Danenberg » Thu Jun 29, 2017 5:02 pm

Call Jim Staib, www.finewoodboats.com ,815-344-9663, he's the copper exhaust pipe guy now.

You appear to be referring to copper plumbing pipe (type L, M), that is NOT what Chris-Craft used? Copper plumbing pipe is measured ID (inside diameter) and will not fit the factory exhaust elbows ID. They used a thinner (.050") wall 'air conditioning tubing' that was measured OD (outside diameter) that would fit into the ID of the cast, exhaust elbows. Plumbing pipe thickness will not fit there.
IF you are going from exhaust elbow to tubing with a rubber hose, I suppose this is possible?
Call Jim before you purchase plumbing pipe.
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Re: Dual exhaust for 283 in a 55' Sportsman

Postby mfine » Fri Jun 30, 2017 4:48 am

If it is not a show boat, do you need to use copper? Rubber exhaust hose will be cheaper, easier, and safer.
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Re: Dual exhaust for 283 in a 55' Sportsman

Postby jim g » Fri Jun 30, 2017 4:03 pm

Its a Chris Craft 283. They were all plumbed with 2 1/2" exhaust hose and about 2 feet or less of copper pipe going through the transom.

Or in the case of a single exit exhaust it was 2 1/2" exhaust hose to a wye then coming out with 3 1/2" exhaust hose to a short piece of copper pipe.
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Re: Dual exhaust for 283 in a 55' Sportsman

Postby parksman » Sat Jul 01, 2017 9:31 pm

That's how it is currently plumbed, with flexible hose from each exhaust manifold to a wye and then to another section of flex hose. There is about a one foot section of copper that attaches to the flex hose and goes through the transom.

I talked to Jim and he advised me to use the same configuration at the transom for the 2nd exhaust. So I'll go from each exhaust manifold to the flex house. From the flex hose I'll exit the transom on each side with copper.

I discovered that the previous owner had repaired the starboard exhaust manifold with JB Weld so I'm going to replace it as part of the process. I located a new Barr manifold on eBay. It says it's for a Chris Craft 283 but not a 3 pass system.

Would my 283 be a 3 pass system? Mine is a 1963 model 283.
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Re: Dual exhaust for 283 in a 55' Sportsman

Postby jim g » Sun Jul 02, 2017 3:41 am

If its the flywheel forward 283 its a 3 pass system. If you use the Barr manifold on it. You can have overheating problems with it. As long as the repaired one is not leaking to the inside. It will work.

If its the 283F flywheel aft. Then the Barr will work.
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Re: Dual exhaust for 283 in a 55' Sportsman

Postby parksman » Wed Jul 05, 2017 2:07 pm

Mine is a flywheel forward so the Barr manifold is definitely out of the question.

Does anyone have any information on the Osco? I found a new one and it has the number 7056 7886 in the top of the manifold casting. In the bottom of the casting it has the number 11241072.

I tried to locate information about it's suitability for a three pass system. But I haven't had any luck. It looks like the manifold that came off of the boat. But I didn't know if the difference was internal and not visible from the exterior of the manifold.

Thanks for the help.
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Re: Dual exhaust for 283 in a 55' Sportsman

Postby jim g » Wed Jul 05, 2017 5:29 pm

Post a picture of it.
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Re: Dual exhaust for 283 in a 55' Sportsman

Postby parksman » Thu Jul 06, 2017 4:18 pm

This is the port side manifold. But there is a starboard side available.
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Re: Dual exhaust for 283 in a 55' Sportsman

Postby mfine » Thu Jul 06, 2017 6:41 pm

My 283 uses newer Osco manifolds in a three way system. They were the only (new) option at the time I did the rebuild but I heard they want out of production.
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Re: Dual exhaust for 283 in a 55' Sportsman

Postby jim g » Thu Jul 06, 2017 8:02 pm

parksman wrote:This is the port side manifold. But there is a starboard side available.


Does it have Osco casted on the top of the manifold between the 2 plugs? If they are your good to go.

The center part will work on either side. Its only the end plates that are port and stbd specific.
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Re: Dual exhaust for 283 in a 55' Sportsman

Postby jim g » Thu Jul 06, 2017 8:05 pm

mfine wrote:My 283 uses newer Osco manifolds in a three way system. They were the only (new) option at the time I did the rebuild but I heard they want out of production.


Osco was sold about 4 years ago. The new owner sent all the patterns to China to have the castings made there. I heard that he caught them selling his products to other people. Confronted them and all the patterns disappeared.

So they are gone and out of business now. They made the only 3 pass manifold.
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Re: Dual exhaust for 283 in a 55' Sportsman

Postby George Emmanuel » Mon Jul 17, 2017 7:18 am

Just curious.....Why do you want to go to dual exhausts? The reason I ask is years ago my dad repowered our 30' Sea Skiff with 283's after removing our old K's. The CC dealer did the installation and they, instead of using what I would think is a more expensive installation of a "Y" to single pipe, installed duals. We did have wet mufflers on all 4 pipes but the sound was loud and not the sweet sound of the previous K's. We regretted having duals.

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Re: Dual exhaust for 283 in a 55' Sportsman

Postby parksman » Tue Jul 18, 2017 12:16 pm

I don't really have a good reason! I knew it came with the 6 cylinder and single exhaust and I thought the 283's came with duals from the factory. And the duals look so dang good too!

Will it make it substantially louder? What are the thoughts of others that have added dual exhaust? Does anyone regret adding the second exhaust to a V8 setup?
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Re: Dual exhaust for 283 in a 55' Sportsman

Postby mfine » Wed Jul 19, 2017 6:11 am

With straight exhaust and no muffler or restriction, I don't think there is any real difference in noise level. Going from low power low compression K's to V8's with more cylinders, higher compression, and more power is likely why he found it louder.
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