I believe it also has full roller rockers. I think it's built similar to the HP500 as far as parts go.
I believe it also has full roller rockers. I think it's built similar to the HP500 as far as parts go.
Does anyone know what ratio/brand? Also does the 377 Scorpion use the same grind cam as the 6.2MX? I was debating installing 1.6 rollers on my 6.2MX but I've been told that this may cause the engine to run too lean and adjusting the fuel/air ratio is not an option with Mercs ECM...
CB,
Don't quote me on this, but I believe the rockers are Crane pieces. Ratio I'm not sure on, but if I was to wager it would be 1.6:1.
the scorpion has 9.1:1 comp ratio ,requires 92 octane .MX has 9:1 comp ratio ,I'm running 89 octane .Nicer air intake cover on the scorp :coffeycup . Both engines have steel cranks , forged piston for scorp , hyper for MX Not sure if the 6.2 MX is internally balanced like the scorpion. I think the scorpion camshaft has more lift :rollside: . Excellent motors both , scorpion is much more expensive !
The 377 has roller rockers and they are 1.5 The cam is a speical cut for merc but the "real close" GM counterpart is #12370846 you can get the specs from a GM performance parts book. I can tell you the lift on the merc part is .510intake and .530exhaust. Also talking with our merc rep.... if you back the timing down about 4 or 5 degrees you can run 87 octane in the 377 I boated all summer this way with no problems and saved money to!
Excellent motors both , scorpion is much more expensive !
I've always run 87 octane in my MX with no problems...
The 377 has roller rockers and they are 1.5 The cam is a speical cut for merc but the "real close" GM counterpart is #12370846 you can get the specs from a GM performance parts book. I can tell you the lift on the merc part is .510intake and .530exhaust. Also talking with our merc rep.... if you back the timing down about 4 or 5 degrees you can run 87 octane in the 377 I boated all summer this way with no problems and saved money to!
Are you sure the MX has roller rockers ? It has a billet crane roller camshaft , but not sure about the rockers [ guess I have to pull the valve covers for a check] . The Scorpion will most likely has rollers . The cam part you gave jives with the ZZ383 GM crate engine which has 425 HP . The merc MX is rated 320 HP at the prop ,that would only yield 340 HP SAE . The MX is calibrated for 87 octane so no retarding neccessary .The scorpion needs 92 oct , and I wouldn't retard it to loose power . The ZZ383 has cast pistons , and I'm not sure now that mercruiser would chuck away the pistons to replace it with forged ones for the scorpion :idea: .
Getting honest info from merc is like pulling teeth. You're better off talking to a tech than a representative .
The MX does not have roller rockers, the 377 Scorpion, which is now out of production did...
The 377 is not the same as the MX 6.2 even though they are the same displacement. The 377 is hand built by merc racing and is a "HP" engine. Some of the goodies are a Lunati forged crank, not GM cast. It has roller lifters same as the 6.2 but the 377 gets roller rockers as well as stainless "sodium filled" valves. The pistons are not forged, they are hypeurtetic. The specs for the 2000 model are 377 crankshaft horsepower and 365 at the prop! Thats better than the non HO version 496! The hand built motors also have a merc seal at the intake bolts, thats how to tell if anyone has tampered with it.
Its sad but 2005 was the last year for the 377 Scorpion
PS I have been a Mercruiser tech for 26 years, and your right merc wont even talk to me?
75 spectra , thanks for the info. I have one observation about the 377 MX though . While the 350 mag engine's crankshaft is ca $ 1200 , the MX engine's crankshaft is $ 2600 . It must be a steel not cast piece for that price :idea: ?
Engine TestMerCruiser MX 6.2 MPI (320-hp) ... Cast-iron block, forged-steel crankshaft, and high-strength aluminum-alloy pistons to ensure durability and reliability. ...
www.boattest.com/105/enginegeneral.aspx - 60k
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