454 Repower Options

Were the old motors fresh water cooled? If not are you adding the FWC kits? It sure would be worth it for longevity and resale value.
 
Saverio you're right. Didn't see the heat exchanger at first. Good idea to have them cleaned and pressure checked before reinstalling.
 
Yes, all good. The heat exchangers are over the front and going out for cleaning and pressure tests. Thanks.
 
some of these motors were delivered with "HALF" fresh water cooling. I know for a fact because I owned two. Half systems only use fresh water in the block and heat exchanger then cool the manifolds with raw water. This was a major part of their demise---the different temperatures between the block and the manifolds caused severe condensation at low rpm(as in the idle time you spend on the way back into marina then shut down motors withe cold exhaust manifolds and full temp block) combined with the cam/valve overlap , this sucked the condensation back in to cylinders and rotted out valve seats. Remedy is to buy larger heat exchanger kits and do "FULL" fresh water cooling including the new manifolds. The stock heat exchangers cant keep up with the extra BTU's of the exhaust manifold heat.
 
Yea im noTching that condensation. Just changed out my manifolds abd risers abd there was alot of rust issue the exhaust chambers on the heads. But only in the two center head chambers. Seemed kinda weird but nothing I can do till they decide to crap out. When I do my repower ill b switching to a full system.
 
when you shut down the motors after a long run, the manifolds are cold. and they have a fresh supply of warm air blowing thru. This causes the condensation on the inside of the exhaust tract-drips down the riser and manifold and collects inthe center two cylinders (mostly in the cylinder that is leaning down depending if you have the v drives or not) making the valve stems seize up and the seats to rust right out of the head. Mercruiser also came up with another solution which is to install "turbulator plates" in between the elbow and the manifold to help catch and steam away any condensation dripping. Search mercruiser turbulator plate. You will only find them listed for the late model dry exhaust systems BUT I purchased them and cut the little dog ears off of them and they fit the standard manifolds perfect.
 
I had the "turbulator"plates. Atleast I think I did. There stainless plates that have a "dish" that points upward? I didn't know what they were called nor could I find them so I didn't reinstall new ones when I did the manifolds abd risers. Im thinking I should find them and put them in? The amount of rust inside the exhaust chambers is kind of frightening lol
 
Sublimetime said:
when you shut down the motors after a long run, the manifolds are cold. and they have a fresh supply of warm air blowing thru. This causes the condensation on the inside of the exhaust tract-drips down the riser and manifold and collects inthe center two cylinders (mostly in the cylinder that is leaning down depending if you have the v drives or not) making the valve stems seize up and the seats to rust right out of the head. Mercruiser also came up with another solution which is to install "turbulator plates" in between the elbow and the manifold to help catch and steam away any condensation dripping. Search mercruiser turbulator plate. You will only find them listed for the late model dry exhaust systems BUT I purchased them and cut the little dog ears off of them and they fit the standard manifolds perfect.
Click to expand...

Interesting...

Did you sandwich the turbulator between two silver Merc. Gaskets?
 
Quick update... port engine is together and transmission mated with new damper plate. Starboard engine should be done by end of this week. I went with aluminum manifolds and risers from Michigan Motorz. I had a six inch spacer block but they don't sell this in aluminum and mating with cast iron is discouraged. I called MM and they said that the three-inch kit is designed to be doubled-up for six-inch applications. We'll see...

I'm going to buy some turbulator plates and resonators online not knowing if they'll fit my 454 exhaust setup but they're not that expensive.

Any recommendations on bilge work before re-installing the engines? I plan on tuning the generator a bit, cleaning, painting, etc.

Thanks.
 
74Alfa said:
Quick update... port engine is together and transmission mated with new damper plate. Starboard engine should be done by end of this week. I went with aluminum manifolds and risers from Michigan Motorz. I had a six inch spacer block but they don't sell this in aluminum and mating with cast iron is discouraged. I called MM and they said that the three-inch kit is designed to be doubled-up for six-inch applications. We'll see...

I'm going to buy some turbulator plates and resonators online not knowing if they'll fit my 454 exhaust setup but they're not that expensive.

Any recommendations on bilge work before re-installing the engines? I plan on tuning the generator a bit, cleaning, painting, etc.

Thanks.
Click to expand...

Everything that you can't easily touch after the engines go back in.
Waste system hoses and duck bills in the pumps.
Hot water heater and maybe install a winterizing bypass kit.
Through hull hoses for engines and AC.
And, easiest to update the ER lighting now so you can admire all your work later...
 
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74Alfa said:
I had a six inch spacer block but they don't sell this in aluminum and mating with cast iron is discouraged. I called MM and they said that the three-inch kit is designed to be doubled-up for six-inch applications. We'll see...
Click to expand...

Before you get two threes, I know where to get 6-inch aluminum spacers that work. I have them and used them when I did my manifolds and risers last year.

http://www.boatpartheadquarters.com/Mercruiser-6-inch-Spacer-p/glm-50605.htm

Give me a call Mike, you have my number if you need help.

--Mike
 
Air O'Nautical said:
Everything that you can't easily touch after the engines go back in.
Waste system hoses and duck bills in the pumps.
Hot water heater and maybe install a winterizing bypass kit.
Through hull hoses for engines and AC.
And, easiest to update the ER lighting now so you can admire all your work later...
Click to expand...

Great advice. Thanks.
 
Ok now im confused. I was told not to use aluminum manifold and risers on cast block and heads due to dissimilar metals. My understanding is that they will disintegrate faster.
Please educate me once again with the pros and cons on aluminum manifold and risers
 
Xplicitlnck said:
Ok now im confused. I was told not to use aluminum manifold and risers on cast block and heads due to dissimilar metals. My understanding is that they will disintegrate faster.
Please educate me once again with the pros and cons on aluminum manifold and risers
Click to expand...

I believe they will corrode due to electrolysis if they are run continually in salt water or at least that was the gist I got from all the research I did before switching over. Mike's 380 and my 330 are both slipped up the Connecticut river near Hartford, very fresh up there. I do about 10-20% of my time in Long Island Sound but the trip home is up the fresh water in the river so the FWC system is cleaned out. As far as the actual manifold to block they are insulated by the graphite gaskets, the only real issue is the bolts, which I changed to new due to rust from the old OEM Mercruiser iron manifolds. The real benefit has been the weight savings, at least 100 lbs off the stern. She also gets on plane faster and the engine room is a tad cooler. I am prepping the boat for this spring and I have given the motors a good going over, after 18 months with the aluminum manifolds they look like the day I put them in. Are they worth it? Well, I might need another 2-3 years to tell. I do know that in fresh water the aluminum manifolds last much longer.

Hey by the way, thanks for all the dinghy help last year. The pictures and information you texted me came in very handy. Not sure I ever thanked you. Maybe catch you on the Sound this season.

--Mike
 
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mj_duell said:
I believe they will corrode due to electrolysis if they are run continually in salt water or at least that was the gist I got from all the research I did before switching over. Mike's 380 and my 330 are both slipped up the Connecticut river near Hartford, very fresh up there. I do about 10-20% of my time in Long Island Sound but the trip home is up the fresh water in the river so the FWC system is cleaned out. As far as the actual manifold to block they are insulated by the graphite gaskets, the only real issue is the bolts, which I changed to new due to rust from the old OEM Mercruiser iron manifolds. The real benefit has been the weight savings, at least 100 lbs off the stern. She also gets on plane faster and the engine room is a tad cooler. I am prepping the boat for this spring and I have given the motors a good going over, after 18 months with the aluminum manifolds they look like the day I put them in. Are they worth it? Well, I might need another 2-3 years to tell. I do know that in fresh water the aluminum manifolds last much longer.

Hey by the way, thanks for all the dinghy help last year. The pictures and information you texted me came in very handy. Not sure I ever thanked you. Maybe catch you on the Sound this season.

--Mike
Click to expand...
gotcha and anytime. I see you have it set up differently. What did you up doing? Looks like u still have room to use the trans door.
 
Xplicitlnck said:
gotcha and anytime. I see you have it set up differently. What did you up doing? Looks like u still have room to use the trans door.
Click to expand...

Well, not to take over the thread, but the dinghy set-up in that pic in my profile is now changed. When I had that set up, I made a stainless pivot bar for the dinghy that attached to the existing weaver davits, that way I could swing the dinghy up and tie it off. Problem was it could not take the weight of the 5hp motor. What I have now is a slightly modified set of Hurley davits with the dinghy almost touching the transom. I used your pictures to figure out if my Dinghy would fit in that area, which it does nicely. I can even open the transom door about 3/4 of the way.

dinghty.jpg
 
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