Good engine swap for Merc. 470?

[marioc]

Hi all!

Wanted to ask what would be a good, somewhat direct, swap for my Merc 470.

I am considering just buying a professionally rebuilt 470 from a marine engine re-builder in VA. But, having read all the different threads on the love/hate realtionship of the 470 I am wondering if there is a better/newer motor...

I've seen threads on 3.0 suggestions, but I think this might be too small of a motor to power my 20 ft CheckMate...


Thanks...

 

[stonyloam]

Re: Good engine swap for Merc. 470?

Nope, but considering that a professionally rebuilt, well maintained 470 should give 10-15 years of good service (mine is 24 years old, 1 head gasket, 1 set of cam seals and a few starters, an alternator conversion and 1 carb. rebuild, still running strong) I would not rule out the rebuild.

 

[marioc]

Re: Good engine swap for Merc. 470?

Terry,

Thanks for the input. I figured a good profesionally rebuilt 470 with Merc. updates(seals, etc.) will give me a number of summers on the water. Not sure if you`re familiar with the outfit out of Norfolk,VA. But, apparently they do very good work. No welded blocks, blocks surfaced, crank heat treated, etc... Let me know if you might need the info. (in case you need one in the future)...

Thanks again,

Mario

 

[fmalott]

Re: Good engine swap for Merc. 470?

stonyloam AHMEN!

 

[marioc]

Re: Good engine swap for Merc. 470?

Stony,

Any tips/pointers you can give me regarding the 470? This is a new motor to me...

I see that you have the Alpha 1 with yours. I have the pre-Alpha (Merc 140 outdrive). Any advantages one over the other(other than being newer...lol)?

Thanks,

M

 

[Bondo]

Re: Good engine swap for Merc. 470?

Stony,

Any tips/pointers you can give me regarding the 470? This is a new motor to me...

I see that you have the Alpha 1 with yours. I have the pre-Alpha (Merc 140 outdrive). Any advantages one over the other(other than being newer...lol)?

Thanks,

M

Ayuh,... Other than you've got the Wrong gear ratio,...

Nope,...
The drives are pretty much interchangeable...


The 140hp is a 1.98:1, the 470 uses the 1.84:1...

 

[stonyloam]

Re: Good engine swap for Merc. 470?

The key to a LONG LIVED 470 is keeping on top of the maintenance. If the engine is new to you you need to assess the overall health of the engine. If you can, get it running on muffs. With a Al block and a iron head the head gasket is vulnerable to failure due to overheating (or just age), and sometimes coolant can leak into the #4 cylinder. So an engine compression check is the first order of business, look for low compression in #4 as an indicator of coolant leakage. You should do a cooling system pressure check to make sure it is in good shape. You can borrow tools from Autozone to do both tests. If you have the original rotor/stator charging system, make sure that it is putting out about 14V, if it is you can stick with it for now, and if the regulator (very $$$$) ever fails, put in a alternator conversion kit. With the engine running check the weep hole on the lower starboard side of the engine circulating pump for leaks. Overheating is the big killer of these engines, so make sure the heat exchanger is in clean and in good shape, including making sure the water flows freely out of the exhaust elbow. Change the impeller in the outdrive every 2 years. Make sure that your antifreeze is up to spec, about 50/50 automotive antifreeze. Make sure your temp gauge is working and keep an eye on it. Doing a compression check and and cooling system pressure check are a good part of the annual maintenance, even with a newly rebuilt engine. About all I can think of, except lots of help here if you need it.

 

[marioc]

Re: Good engine swap for Merc. 470?

Stony,

Thanks for your willingness to help... Long story, I purchased the boat/motor as a project. I was told the motor was something it wasn't(rebuilt), etc...
I work on lots of things, but never on marine motors. Until now...

The motor does have an alternator on it, just haven't looked at it real well... Motor had some parts off of it, so between a 8 month pregnant wife and my business haven't had the time I wanted to look at it thoroughly.

Figured I would rather spend $4-5k and redo the boat and have what I want, rather than spending $12+++k and having just some standard boat...

So, according to Bond-o, I have the wrong gear ratio!!! Wow, that's nice. Another surprise... Can I change the gearing? Or just go with a Alpha/Bravo?

PS... I was just near you for Thanksgiving... visiting family. I live in TN...

M

 

[fmalott]

Re: Good engine swap for Merc. 470?

still don't know what year you have, you will either have a MC-1 or a I-R outdrive 1976 - 1982 MC-1, 1983 - 1984 I-R

 

[Eric 3.7LX Alpha 1]

Re: Good engine swap for Merc. 470?

Here is a chart with different drive/engine ratios attached: You can replace the gears in the upper unit to the correct one, but the parts and tools to do the job would cost more than a new aftermarket upper.

 

[marioc]

Re: Good engine swap for Merc. 470?

Eric,

I copy that! I've seen a couple guys mentioning that it's cheaper to just get another outdrive...
Would it hurt to run the 1.98:1 gear with my setup?

I'll have to check and see, but I know it's around an 1981 vintage outdrive... From what I remember seeing, I believe it is a MC-1... I'll double check!

Mario

 

[stonyloam]

Re: Good engine swap for Merc. 470?

I copy that! I've seen a couple guys mentioning that it's cheaper to just get another outdrive...
Would it hurt to run the 1.98:1 gear with my setup?

I am not an outdrive/prop guy but you are looking for a gear/prop combination that will give you the performance characteristics you are looking for (eg high speed, or good out of the hole for pulling skiers) and a WOT (wide open throttle) rpm of about 4200. The 1.98 and 1.84 may be close enough that the correct prop will give you what you need, but I DO NOT KNOW. For example a prop that is correct for the 1.84 would tend to let the engine over rev at WOT. Find out what size prop you have (should be stamped on the hub) then I would suggest that you go to the prop forum and see what they say.

 

[Bondo]

Re: Good engine swap for Merc. 470?

Would it hurt to run the 1.98:1 gear with my setup?

Ayuh,....Commonly available prop pitches, that fit yer drive, run from 15" to 23", sometimes a 25"...

If yer boat was runnin' a 15" or 17", on it's Original ratio, you'll probably be able to pitch to the rpms needed...
If the boat was runnin' a 21" or 23" prop, you don't have any room left to work with in prop pitches...

 

[fmalott]

Re: Good engine swap for Merc. 470?

Excellent info Bond-o

 

[marioc]

Re: Good engine swap for Merc. 470?

excellent info bond-o

ditto!!!

 

[marioc]

Re: Good engine swap for Merc. 470?

So, the prop is a 14.5 " X 17. Since this is a "power boat", I calculate the speed to be around 30 ish mph. Does that sound right(with 470 motor)?

 

[marioc]

Re: Good engine swap for Merc. 470?

Stony,

What prop are you running on your 470? I have a fairly light boat, so I'm thinking about going to a 24 pitch blade for some more cruising speed...

I believe the one on there now is mostly for pulling.

Any comments?

 

[Bondo]

Re: Good engine swap for Merc. 470?

So, the prop is a 14.5 " X 17. Since this is a "power boat", I calculate the speed to be around 30 ish mph. Does that sound right(with 470 motor)?

Stony,

What prop are you running on your 470? I have a fairly light boat, so I'm thinking about going to a 24 pitch blade for some more cruising speed...

I believe the one on there now is mostly for pulling.

Any comments?

Ayuh,.... Goin' from a 17" to a 24" is gonna induce detonation, leading to a hole in the pistons, 'n a Junk motor...
The motor will lug itself to Death...

 

[stonyloam]

Re: Good engine swap for Merc. 470?

You would ask that LOL. I think it is a 15 1/4-19. I will try to remember to check it tomorrow.

 

[marioc]

Re: Good engine swap for Merc. 470?

Bond-o,

Excuse me ignorance... Still learning the whole boating "thing". I love anything with motors...just have never worked much around boats.

I did grow up on water, when I was young... This seems a common theme with a lot of people on here. Growing up on water...not having been around water for years...going back to the water...LOL

Your comments make sense...Thanks!

M