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Marine engine differences

P

piratesteve

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"Could someone with experience

"Could someone with experience state the diffenences between these Engines and an Automobile application, I will be operating in both fresh and saltwater.
Any Cautions or Up-Grades that I should pay attention to would also be appreciated.
I have found a local Machine Shop to go through my 165 hp Mercruiser (Inline 6, 250 cu in).
They advertise that they do Marine Engines but I would like to be sure that this comes out ok."
 
"Stainless head gaskets, bronz

"Stainless head gaskets, bronze freeze out plugs, and a marine camshaft are the most common differences.

JEff"
 
"Ayuh,.......

As long as th

"Ayuh,.......

As long as they're doing up Your Block,..... I see No Problems.....

But,....
Replacement Blocks for Your motor sometimes Don't have the Required Holes for the Front Motor Mount......"
 
"Thanks Jeff,
So I already kn

"Thanks Jeff,
So I already knew the Block was different, what I read was that a Truck Block was the start of a Marine Engine.
Brass Freeze Plugs (because of corrosion)
Marine Cam (To close the Valves sooner to solve water intrusion issues)
Head Gasket, stainless? why not a composition? (again corrosion issues)
Did I not read that the Pistons should be flat tops?
Valves should be stainless steel?
This is what I had found out previously but I was seeking confirmation and totality.
Steve"
 
"Head Gasket, stainless?

Ab

"Head Gasket, stainless?

Absolutely!

Did I not read that the Pistons should be flat tops?

They need to be low compression, which is flat topped--virtually the only way you'll find 'em nowadays.

Valves should be stainless steel?

No. Ordinary work as well (maybe better).

Jeff"
 
"That doesn't answer my qu

"That doesn't answer my questions.
Why not Composition? This way there would be no Dissimilar Metals to present potential Problems. Depending on the grade of Stainless Steel there could be quite a difference on the Galvanic Scale with Cast Iron.
I just built an Engine for my Street Rod and High Compression Pistons are still available, just not used very often. What should the Compression Ratio be?
I would suggest that the Valves should be Stainless Steel if the Boat was to be used in Saltwater.
Please remember my Original Question, I was looking for a Complete List of the Differences, not just an opinion.
Steve"
 
"P. Steve: While you are rebui

"P. Steve: While you are rebuilding, upgrade to a full "fresh water" cooling system since it will be in salt water now and then. You could probably use a new wiring harness due to the age of the old wire--internal corrosion. If you can't buy a mfgd. harness, use tinned wire to make your own to greatly reduce wire corrosion. Guy"
 
"Guy,
That is a good idea abo

"Guy,
That is a good idea about a Freshwater Up-Grade. I have been looking for a "Kit" for this old (1970) 165 hp Mercruiser. As of yet I haven't seen one, any suggestions?
I was lucky enough (or dilligent because of a search for over a year) to find a Freshwater Boat!! This Skijack had been stored inside or under cover most of it's life. The wiring so far is in very good condition. I will know more about the wiring as I begin the repairs and start using the systems but I intend to replace anything that is in poor condition.
Steve"
 
"I got a half system on mine,

"I got a half system on mine, so far so good. The exhaust will rot to hell but my exhaust was used already and I'm not sure if a full system would fit with all the stuff in my engine compartment."
 
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