Swapping 470 for 3.8

[8AteEight]

Hi all. I was looking for alternatives for my boat. The Merc 170 (470) was doing ok'ish, But the oil pressure was really low. So Im starting into the idea of rebuilding it. Someone suggested putting in a 3.8l or even a 4.3l, but I am NOT into buying tons of ancillery parts (well, not being nickeled&dimed to death) So....has it been done?? Can it be done on a budget?? what all would be needed??<br /><br />Thanks in advance.<br /><br /> Jon

 

[KaGee]

Re: Swapping 470 for 3.8

I believe you may have to change out everything. A v6 will require a gear change in the upper unit. In short, it may nickle and dime ya.

 

[Bondo]

Re: Swapping 470 for 3.8

The Only Practical Way to do what you wish,......<br /><br />Is to buy a Donor Boat with a Complete, Running Driveline.......<br /><br />Then Junk It,+ Install the New Driveline in Your Hull.......<br /><br />You can recoup Some of the Expence by selling off the Extra Parts you will no longer be Needing.......

 

[whywhyzed]

Re: Swapping 470 for 3.8

what they said- <br />Your outdrive ratio is actually proper for a 3.8 2BBL @ the same 170HP as your 470.<br /><br />4.3 4BBL would certainly require a different ratio.

 

[MrBill]

Re: Swapping 470 for 3.8

The 470 and subsequent 3.7 liter engines tend to operate with low oil pressure. I worried about mine for years and it still runs greats and has good compression. Unless you've found other problems, such as low, or problematic compression, don't assume that the low oil pressure mandates a rebuild or engine swap.

 

[8AteEight]

Re: Swapping 470 for 3.8

Yeah, I guess this is true. I took it out on the lake for the first time, and it ran better than it did all last year. The O.P. is still low after it warms up, but it does run good, so I guess I wont really worry about a motor swap just yet. <br /><br />Now, what about a performance rebuild?? I know it uses 460 pistons, rods, and head; but Ive been told its almost worthless to add performance parts. I was thinking about H-beam rods, and Forged pistons, and a cam to make it run up to 7k. Does anyone have opinions??<br /><br /><br />Thanx again, youve all ben quite helpful.

 

[8AteEight]

Re: Swapping 470 for 3.8

 

[sikpupy]

Re: Swapping 470 for 3.8

bump, to the top<br /><br />seems everyone can bash these engines or love them but there is no more support other than that.<br /><br />oh well, it is a good question I am also waiting on an answer to as I am looking into lighter aluminum rods.

 

[TilliamWe]

Re: Swapping 470 for 3.8

Ok, well I don't have one of these engines, so I'll speak in generalities:<br />A 7000rpm cam is a bad idea. Most sterndrive powered engines run under 5000rpm. I don't think the drive would like 7000rpm too much. And what would a cam like that do to low end torque? Also, would you really want a rough running 230 cubic inch four cylinder spinning that fast? I doubt it.<br />Better engine internals would be fine. But why spend money on an engine that Mercruiser doesn't make anymore?