Truck 5.7 engine into boat

[Galvez83]

Hey folks, just to pick your brain. I am about to replace my busted seized engine for a 5.7 vortec off a junkyard. Boat is a 2000 Four Winns 238 Vista with dp-sm 1.95. Other than the head gasket, core plugs which will get done before putting into the boat. What can be done to obtain more hp from the yard motor. I read several places about truck cams being almost equal to marine. I am really looking to increase power. I dont know specific cams that might be recomended or springs, valves and so forth. Please advise.

 

[tpenfield]

There is not a whole lot that you can do with the cam on a marine engine . . . because . . . you need to have sufficient valve timing separation in order to avoid 'reversion' of the exhaust at idle speeds and the resulting hydro-lock of the engine

Truck cams are similar to marine cams in that regard, but I'm not sure of the specifics. Boats need a good amount of torque at lower RPM's and the marine cam (or truck cam) is going to do that for you. Overall HP increases of marine engines are often achieved on the 'high end' by getting a few extra 100 RPM out of them.

Is this a carburator or fuel injected intake? I assume you know to swap everything fuel, exhaust, electrical related over to the donor engine.

 

[Scott Danforth]

Hey folks, just to pick your brain. I am about to replace my busted seized engine for a 5.7 vortec off a junkyard. Boat is a 2000 Four Winns 238 Vista with dp-sm 1.95. Other than the head gasket, core plugs which will get done before putting into the boat. What can be done to obtain more hp from the yard motor. I read several places about truck cams being almost equal to marine. I am really looking to increase power. I dont know specific cams that might be recomended or springs, valves and so forth. Please advise.

is the motor fuel injected or carbureted?

there are some marine cams you can upgrade to. the Comp Cams XM270HR is the largest cam you can run with wet exhaust, or you run inter reversion that Ted mentions

you can also port match the intake and heads, and deflash the combustion chamber

if running a carb, run a 2" carb spacer for a fatter mid-range torque curve. what carb?

 

[Galvez83]

Motor is TBI. Yes i have done the swap before but i wasn't sure what was need regarding cam, valves and or springs to get more ponies.

 

[Scott Danforth]

Motor is TBI. Yes i have done the swap before but i wasn't sure what was need regarding cam, valves and or springs to get more ponies.

Ditch the TBI as any change will require reprogramming. and TBI is not very efficient or easy to get more HP. a simple carb would give you more power just by flowing more CFM

 

[Galvez83]

Ditch the TBI as any change will require reprogramming. and TBI is not very efficient or easy to get more HP. a simple carb would give you more power just by flowing more CFM

What would the swap entail in regards to supplies? Carb and new manifold is known is needed.

 

[Scott Danforth]

What would the swap entail in regards to supplies? Carb and new manifold is known is needed.

a good quality marine manifold
a good quality marine carburetor
a good quality carb spacer
gaskets

with a cam swap, some mild head work for the higher lift, valve spring swap, , you can get to about 320hp at the crank (about 300hp at the props)

if you want more than that, you need to go to a stroked rotating assembly and build a 383.

 

[Galvez83]

a good quality marine manifold
a good quality marine carburetor
a good quality carb spacer
gaskets

with a cam swap, some mild head work for the higher lift, valve spring swap, , you can get to about 320hp at the crank (about 300hp at the props)

if you want more than that, you need to go to a stroked rotating assembly and build a 383.

Got it, what about all the computer wiring? Is there anything that needs to be done to bypass or can it stay ?

 

[Scott Danforth]

it could stay, you could remove it.

however if your boat runs fine, I suggest just using it as is.

 

[Bondo]

Got it, what about all the computer wiring? Is there anything that needs to be done to bypass or can it stay ?

Ayuh,..... Yer gonna use the harness off the original boat motor, ain'tcha,..??

The pickup's harness is scrap,....

For the carb, ya can't go wrong with an Edelbrock 1409,.....
The 1410 is alittle big for an SBC,.....
'n all the brackets, cable hook-ups, etc are the same as Merc has used for their 4bbl carbs, which is a carbon copy of the Edelbrock,...