Really need your help with 350 mag replacement engine??
#21
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Here are some differences I've run across between Merc and GM crate engines:
Marine cam with low overlap, and wide lobe centers (pushes torque peak to higher rpm, while preventing reversion).
Stainless steel head gaskets
Brass freeze plug (some crate engines do have these)
Lower compression pistons (generally 9.4:1 or less)
Inconel exhaust valves to stand up to the constant high exhaust temperatures
Hard anodizing on aluminum heads to prevent corrosion
Better quality block paint to prevent corrossion
Bigger oil pan
Marine distributor
Marine carburetor or fuel injection
Full floating piston wrist pins (high performance engines)
******
I'm sure there are a bunch of other things, too (valve springs, retainers, etc). It doesn't mean you couldn't start with a crate engine, but it would be best to make a few changes before pressing it into marine service.
Michael
Marine cam with low overlap, and wide lobe centers (pushes torque peak to higher rpm, while preventing reversion).
Stainless steel head gaskets
Brass freeze plug (some crate engines do have these)
Lower compression pistons (generally 9.4:1 or less)
Inconel exhaust valves to stand up to the constant high exhaust temperatures
Hard anodizing on aluminum heads to prevent corrosion
Better quality block paint to prevent corrossion
Bigger oil pan
Marine distributor
Marine carburetor or fuel injection
Full floating piston wrist pins (high performance engines)
******
I'm sure there are a bunch of other things, too (valve springs, retainers, etc). It doesn't mean you couldn't start with a crate engine, but it would be best to make a few changes before pressing it into marine service.
Michael
Last edited by Michael1; 05-06-2007 at 09:20 PM.
#22
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Join Date: Oct 2005
Location: Ankeny IA
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At least as of last year, the mouse motors (small blocks) and the lower performance big blocks did not have Inconel exhaust valves. I am not sure if they were even HD rated. Mercury's price for them was something like $8-9 apiece. Way too cheap for Inconel.
#23
IMO I think a 6.2 (320hp) with a B1 outdrive should do the trick. I think they can be had with closed cooling if you are running in salt. Maybe a little pricey, but reliable, warrantied power and an engine that should last a long time.
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06-20-2006 07:09 AM