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Exhaust manifold for Merc MCM 470, 3.7L, 224 CID November 82 build serial 6294262

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woolybear

New member
I am trying to find an inexpensive exhaust manifold to put on an old $500 boat. Mercruiser part # 816219 A4 is much too expensive at US$2K. Can anyone give me any leads on cheaper alternatives or possibly an exhaust manifold retrofit, for a cheaper readily available manifold setup altogether?
 
The reason you are having so much trouble is this motor is a one of a kind motor manufactured by mercury marine.

If it were a GM or Ford base motor there would be many choices.
 
The engine block yes - though my understanding is that the MCM 470 cylinder head is off the Ford 460 powerplant. My experience with this exercise is that if you're an owner reluctant to pay several thousands of dollars for a brand new manifold going into an old boat - as I am, unless you have a boat in a condition which warrants and justifies this level of reinvestment - which I don't - your choices are very skinny indeed. From all I've heard this particular Mercruiser engine delivered very good power and performance for its weight. I'd be intrigued to learn why it was discontinued and not subject to further development.
 
It was discontinued because it was plagued with internal motor issues. Rods, pistons and also manifolds........

Yes it is a big block for head but you MUST use the correct manifold. No other will work without a great deal of modification.

It was lets just say an experiment that failed. they stopped making them around 1989 but due to chronic problems had to warranty them into the mid '90's.

Regardless of what you think of its potential. it is a lost cause without spending a lot of money either up front or over time. And as time marches on parts for that specific motor will become less and less available.
 
Oh your last sentence is so true. And I thought I was getting a great deal, my impromptu education on the pros and cons of the Mercruiser 470 engine - quite aside from being very tiresome is proving labour intensive / time consuming and financially expensive. But as they say, a good education is never cheap. The installation and subsequent tedious dismantling of the top end should have served as a warning.
 
Been there done that.......worked on many.........had them apart and back together.........when they are good they run good BUT when they don't it is a can of worms.
 
kghost said:
It was discontinued because it was plagued with internal motor issues. Rods, pistons and also manifolds........

Yes it is a big block for head but you MUST use the correct manifold. No other will work without a great deal of modification.

It was lets just say an experiment that failed. they stopped making them around 1989 but due to chronic problems had to warranty them into the mid '90's.

Regardless of what you think of its potential. it is a lost cause without spending a lot of money either up front or over time. And as time marches on parts for that specific motor will become less and less available.
Click to expand...

Woolybear, I must agree with Jack.

Not only was this engine short lived, and not only did this engine have issues, as Jack mentions, it also had charging system issues, front engine cover issues, the camshaft drives the engine circulating pump impeller and this area shares a failure prone seal.

While the cylinder head may be a 460 Ford, the exhaust manifold is Merc Proprietary.
You will not find an alternative that is not a propriety part, even though it may be an after-market component.


Seriously, I'd cut your losses now, and go in another direction.

$500 boats are never inexpensive and are never investments... and in particular with this engine.



.
 
Does anyone have, or can anyone point me in the direction where I can find a good used exhaust manifold for a Mercruiser 470 - Engine Serial # 6294262. From Mercruiser Classic boat hotline I'm advised this engine is a November 82 build. The part number required is: Mercruiser 816219A4 or GLM 51200 or Barr Marine MC-1-99908. Off the manifold I'm trying to find a replacement for I see the numbers ending 907 and 1482 in the casting. The first part of number in both case is illegible. The riser (which I don't need) paired with this manifold is undamaged and I will be reusing it, it has two numbers in the casting: 90879 and 12812. I'm finding there are several type / variables on this 470 manifold and I'm having trouble sourcing the correct one.
 
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