Is there another motor that can replace Mercruiser 470?

[J & K plus 5g's & 1 b!]

We just bought a 1981 Wellcraft Family boat with a Mercruiser 470 in & out board motor (170hp). We just found out from our mechanic that the inboard motor is blown So now we are on the hunt for a motor to put in our boat so we can take our family out on the lake(as we promised our children when we bought this blown boat) We are hopeful that someone out there can tell us if the Mercruiser 470 is the only inboard motor that we can put in its place. We have been told that to rebuild ours would cost a couple grand and we are not ready for that. If our options are more than just the Mercruiser, we have more of a chance in getting it fixed sooner rather than later. (And just an FYI, the outboard seems to be in great condition.) Please help! Thank you SO much!

 

[Rocky_Road]

Re: Is there another motor that can replace Mercruiser 470?

When I researched this for my 470, I learned that the 3.0L was compatible with my Alpha outdrive. The main problem was setting up a stringer for the front mount.

The 3.0L is a popular engine...and there are a 'ton' of them out there. You can find both new, and used, on eBay.

 

[TilliamWe]

Re: Is there another motor that can replace Mercruiser 470?

J&K, nothing is a "direct" replacement for that engine. A 3.0 4 cyl is close, but it's only 140hp. And less torque. You'll probably be underpowered if you use that engine. The best thing to replace it with is either a 4.3 or a 5.7. Either way, you are going to spend Thousands of dollars.
You could rebuild the 470, but you'll be left with an engine with known reliability issues, obsolete parts, and very expensive repairs. Basically you bought the worst engine Mercruiser even made (cause they made it themselves, not bought from GM or Ford). Do a search on here to see all its issues.
Right now, it sucks to be you. Sorry. Best of luck to you.

 

[Rocky_Road]

Re: Is there another motor that can replace Mercruiser 470?

J&K, nothing is a "direct" replacement for that engine. A 3.0 4 cyl is close, but it's only 140hp.

Actually...the 3.0 is rated at the prop, and the 470 was rated at the flywheel. I have read that if you were to rate the 470 at the prop, it would be almost identical.

All said, they are awfully close in the horsepower range...but the 470 has always been seen as a very high torque engine, for its' size.

The 3.0 mates up to the Alpha, without any modifications whatsoever...rear engine mounts included. I believe that the wiring harness is a direct plugin, also.

 

[IVAZ]

Re: Is there another motor that can replace Mercruiser 470?

The power of the 3.0 might actually be very comparable to the 470. This link pretty much emphasizes what TilliamWe and Rocky wrote. http://www.mercruiserparts.com/mercury_mercruiser_3-7.htm . It does not sound like anything is a direct swap unfortunately. The link actually says they will buy the 470 from you.

 

[cooter2506]

Re: Is there another motor that can replace Mercruiser 470?

Also wasnt the outdrive ratio for the 470 the same as a 6cylinder? If so he would have to change the drive ratio too for th 3.0.

 

[Rocky_Road]

Re: Is there another motor that can replace Mercruiser 470?

The power of the 3.0 might actually be very comparable to the 470. This link pretty much emphasizes what TilliamWe wrote. http://www.mercruiserparts.com/mercury_mercruiser_3-7.htm It comes from http://www.mercruiserparts.com . It does not sound like anything is a direct swap unfortunately. The link actually says they will buy the 470 from you.

The link refutes the statement "You'll probably be underpowered if you use that engine." Mercury backs up my contention that if your boat currently has a 470, then the 3.0 will give you equal performance.

The link also backs me up on the installation: "A new complete ready to install 3.0L is less expensive than the 3.7 longblock only and is a simple replacement."

Like I pointed out...set a new stringer in the bilge, and the engine drops in.

 

[Rocky_Road]

Re: Is there another motor that can replace Mercruiser 470?

Yeah...I see it, IVAZ!

It didn't read that way, while I was typing! :redface:

 

[Rocky_Road]

Re: Is there another motor that can replace Mercruiser 470?

Also wasnt the outdrive ratio for the 470 the same as a 6cylinder? If so he would have to change the drive ratio too for th 3.0.

Not sure about that.

When I was putting all the pieces together, trying to decide about my 470, all the installers I talked to had no issue with my current Alpha setup.

Ended up buying a second boat...with a 3.0L. I am still trying to decide about the 470...!

 

[TilliamWe]

Re: Is there another motor that can replace Mercruiser 470?

Well, there you go. Ain't "technology" wonderful. 25 years later a 181cid engine performs as well as a 224cid engine.
A 470 would have a 1.81 ratio drive, where a 3.0 would get a 1.97 (or a 2.0, whatever Mercruiser uses these days). You may need a lower pitch number prop, but maybe not, if the power levels are truly the same.
As far as the front motor mount, I though the 3.0 used a half moon shaped thing like the 470? Oh well, that's better than changing "everything" like you have to do to put in a V6 or V8.

 

[mrsemi05]

Re: Is there another motor that can replace Mercruiser 470?

since you guys are kinda talkin about it how hard would it be to install a 350 chevy v8 into one of these boats???? its just changin the mounts and wiring right????

 

[IVAZ]

Re: Is there another motor that can replace Mercruiser 470?

since you guys are kinda talkin about it how hard would it be to install a 350 chevy v8 into one of these boats???? its just changin the mounts and wiring right????

I think the drive would have to be regeared (Im not sure what V8s use). The stringers might also need to be worked on.
I have no doubt it could be done but, it would be more costly.

 

[Rocky_Road]

Re: Is there another motor that can replace Mercruiser 470?

since you guys are kinda talkin about it how hard would it be to install a 350 chevy v8 into one of these boats???? its just changin the mounts and wiring right????

Physical size of the bigger block would probably be the issue. An engine bay set up for a 470, will have to see some serious reworking to fit a V-8.

At least mine would!

 

[TilliamWe]

Re: Is there another motor that can replace Mercruiser 470?

since you guys are kinda talkin about it how hard would it be to install a 350 chevy v8 into one of these boats???? its just changin the mounts and wiring right????

No need to change wiring. All Mercruiser engines are self contained. Plug in that big black plug, and they'll work. Even your guages.

The front mount is the biggest issue with a V in place of that I. But it can be done, and it's not that complicated to figure out. Of course it's best to do it to a boat that had a V8 as an original option, that way the motor cover will fit, and the fuel tank won't be in the way. But you will need everything from the transom forward. And yes the gear ratios will not be right (a 5.7 in a 20'ish boat is gonna get a 1.47 [1.50] where the 470s had 1.81s), but a higher pitch prop can compensate. For example, my dad installed a 260hp 350 Mercruiser engine in a Four Winns 19'er that had a 470 in it. He fabricated a front motor mount out of wood, so it was simple. Since the boat was available with a V8, he didn't have any front of the engine clearance issues. The 350 needed a 25p 3 blade prop to not overrev, where the 470 used a 19p.

 

[artificialreef]

Re: Is there another motor that can replace Mercruiser 470?

Cmon, 470 haters. What about the alternater, 4 inch riser and cam buddy upgrade for the 470. Its a torque monster loved by the short track racers

 

[IVAZ]

Re: Is there another motor that can replace Mercruiser 470?

Cmon, 470 haters. What about the alternater, 4 inch riser and cam buddy upgrade for the 470. Its a torque monster loved by the short track racers

Who was was hating on it? What do short track racers have to do with this guys problem?
BTW a big block is a torque monster not a 4 cylinder. Did you not read the link saying a 3.0 is comparable to the 470?

 

[abj87]

Re: Is there another motor that can replace Mercruiser 470?

Or you can rebuild what you got..... 5.7 sounds enticing though