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Old 05-08-2019, 11:17 AM   #1
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Log style questions & possible conversion to center riser for a 1984 mainship 36 dc?

Hi, new here, Owned this boat for 10 years.. I have twin 270 crusaders with log style manifolds with what looks to be block offs(spacer?) water outlet adapter(for closed cooling), 8" risers and elbow outlet. any clarafication is appreciated

can anyone tell me if the elbow outlet for this boat are 3" or 4"? (this is important to know ASAP)

I just moved the boat to get two new engines installed and im figuring out the manifold situation. I havent taken them off yet to check to make sure they are ok. I think its in my best interest to replace the risers and possibly re uses the manifold if they check out ok. I dont know the longevity of them and im trying to keep costs down.

Im looking at worst cast scenario(replacing all the manifolds and risers). and thus why i brought up converting to center riser since they are cheaper and I can run longer hose and connect it to the exsisting hose to save money.

from what i was told the manifolds and risers are steel however i know salt water is my enemy and dont want to ruin two new engines. any adivce and suggestions are appreciated. I have to go and take the manifolds off soon and have them pressurized and tested obviously.

Any help from fellow main ship owners is appreciated.

heres a pic for reference

thanks in advanced!
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Old 05-08-2019, 11:41 AM   #2
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Greetings,
Can't help you but welcome aboard.
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Old 05-08-2019, 12:13 PM   #3
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Greetings,
Can't help you but welcome aboard.
Thanks 😊
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Old 05-08-2019, 02:22 PM   #4
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Old 05-08-2019, 07:44 PM   #5
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Welcome aboard.
thank you too! I hope someone can clear some things up for me
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Old 05-09-2019, 04:21 AM   #6
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Originally Posted by beerock View Post
Hi, new here, Owned this boat for 10 years.. I have twin 270 crusaders with log style manifolds with what looks to be block offs(spacer?) water outlet adapter(for closed cooling), 8" risers and elbow outlet. any clarafication is appreciated

can anyone tell me if the elbow outlet for this boat are 3" or 4"? (this is important to know ASAP)

I just moved the boat to get two new engines installed and im figuring out the manifold situation. I havent taken them off yet to check to make sure they are ok. I think its in my best interest to replace the risers and possibly re uses the manifold if they check out ok. I dont know the longevity of them and im trying to keep costs down.

Im looking at worst cast scenario(replacing all the manifolds and risers). and thus why i brought up converting to center riser since they are cheaper and I can run longer hose and connect it to the exsisting hose to save money.

from what i was told the manifolds and risers are steel however i know salt water is my enemy and dont want to ruin two new engines. any adivce and suggestions are appreciated. I have to go and take the manifolds off soon and have them pressurized and tested obviously.

Any help from fellow main ship owners is appreciated.

heres a pic for reference

thanks in advanced!
I'll chime in as I have recently come from the dark gas side. Maybe mainships all had a particular exhaust size, but I'm betting yours is 3".

The Crusader 270 (arguably the best marine gas inboard ever made - see this article by David Pascoe)
https://www.yachtsurvey.com/GasEngines.htm'
is a 350 GM truck engine; I think you're right they could have either 3 or 4" exhaust. I am pretty sure they are interchangable - you should measure what you have. It looks like 3" exhaust hose to me.

It definitely looks like a FWC setup. Here is a pic I found of a Crusader fresh water cooled water flow diagram that explains what your hoses all are...not positive what this is representing is your engine, but it sure looks close to me...what's missing in the diagram is the 8" riser, but that series of gaskets and plates is in the same place your riser is. Your riser is there because your engine is likely at or below the WL, and that is how Crusader gets the exhaust a little higher than the waves hitting your exhaust to prevent sea water from coming in from swells.

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I would encourage you to do whatever you can to keep up the Crusader quality in your boat. If you can have those motors rebuilt, or replace them with Crusader rebuilds. I know there area a lot of marine crate motor 350's out there for cheap, but that is what you will get. The fact that you've had the boat 10 years and are just now doing the engines, and they were probably old when you got the boat...see pascoe's article again!

I would also encourage you to keep the current exhaust set up. BARR makes some affordable replacement risers and exhaust elbows for your engine, I just sampled a couple online sites and the 8" risers were in the $170 range and the elbows less than $100. The reason to stick with the crusader setup is that cooling system works, and works well. Your manifolds are likely in tip top shape as they have fresh water (and coolant) in them, so shouldn't have any rust. I don't know you would have to do anything to test them - if they are in fact coolant filled they will be in the same shape as your blocks. As long as the joint between the raw water side and the fresh water side is intact you should be fine. You'll get a look at that visually when the two are seperated.
Crusader manifolds, risers, and elbows are cast iron, as are the BARR replacement risers and elbows.

My gas engines were OMC, and originally had log style, not anywhere close to the quality of the Crusaders you have. I converted them to the BARR center riser style first thing back in 2004 as the old manifolds were toast. The BARRs worked ok, but it was a challenge to get the cooling water flow through the manifolds correct in my engines. It took some figuring to make it work right, and that means I had some overheating issues until I did get it figured out right.
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Old 05-09-2019, 05:48 AM   #7
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Cannot tell for certain from your photo but it looks like the manifolds may be part of the closed loop system. They may be fine (made of the same stuff as the engine). The elbows will be raw-water cooled for sure and are probably end of life by now.

Quote:
Originally Posted by beerock View Post
Hi, new here, Owned this boat for 10 years.. I have twin 270 crusaders with log style manifolds with what looks to be block offs(spacer?) water outlet adapter(for closed cooling), 8" risers and elbow outlet. any clarafication is appreciated

can anyone tell me if the elbow outlet for this boat are 3" or 4"? (this is important to know ASAP)

I just moved the boat to get two new engines installed and im figuring out the manifold situation. I havent taken them off yet to check to make sure they are ok. I think its in my best interest to replace the risers and possibly re uses the manifold if they check out ok. I dont know the longevity of them and im trying to keep costs down.

Im looking at worst cast scenario(replacing all the manifolds and risers). and thus why i brought up converting to center riser since they are cheaper and I can run longer hose and connect it to the exsisting hose to save money.

from what i was told the manifolds and risers are steel however i know salt water is my enemy and dont want to ruin two new engines. any adivce and suggestions are appreciated. I have to go and take the manifolds off soon and have them pressurized and tested obviously.

Any help from fellow main ship owners is appreciated.

heres a pic for reference

thanks in advanced!
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Old 05-09-2019, 09:30 AM   #8
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Crusaders were always the full fresh water, Center risers are half systems. If you stay with the crusader, which I would, make sure your long block uses a good circulating pump.
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Old 05-10-2019, 09:00 AM   #9
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Crusaders were always the full fresh water, Center risers are half systems. If you stay with the crusader, which I would, make sure your long block uses a good circulating pump.
I thought you can make center riser exhaust fully cooled too with block off plates just like logs..

Ill be at the boat on sunday to take the manifolds off
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Old 05-10-2019, 06:13 PM   #10
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Actually, think you are correct, it is possible, though all of my center risers were half systems. But...Crusader was always known as the best cooling system, tip to tail. I would replace and zero hour the parts that see saltwater and keep/maintain the rest of the system. Yeah, they are more expensive castings, but you only replace the risers.
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