Re-powering a soon to be mine chieftain.

[reorod]

Its that new guy REOROD again. I'm a mechanic but not a (marine mechanic) and I,m thinking of repowering the boat in mind, (STARCRAFT CHIEFTEN 22ft-24ft) with an alternate engine from Rapido but guide me with marine wisdom with tech that will save me nightmares and good parts availability. According to the quick decricptions from Rapido: (Marine engine in Florida) the true marine engines will fit all mercruiser outdrives. Concidering GM 4.3v6 as replacement for 120 for 165 that exist in chieftains. Is weight an issue with this engine, heat/air circulation, etc. Please help as I,m putting a road-map for restoration together and need the welth of tech info from this forum. If this is not the correct area please direct me.

 

[CheapboatKev]

Re: Re-powering a soon to be mine chieftain.

Its that new guy REOROD again. I'm a mechanic but not a (marine mechanic) and I,m thinking of repowering the boat in mind, (STARCRAFT CHIEFTEN 22ft-24ft) with an alternate engine from Rapido but guide me with marine wisdom with tech that will save me nightmares and good parts availability. According to the quick decricptions from Rapido: (Marine engine in Florida) the true marine engines will fit all mercruiser outdrives. Concidering GM 4.3v6 as replacement for 120 for 165 that exist in chieftains. Is weight an issue with this engine, heat/air circulation, etc. Please help as I,m putting a road-map for restoration together and need the welth of tech info from this forum. If this is not the correct area please direct me.

You can get some advice here...But I tell ya amigo..
The Mercruiser/OMC forum is where the schmarty pants hang out..
Actually Bond-O did this swap in a Starcraft himself, though he personally doesnt spend much time here in the SC forum.

I dont know much, trust me on that but.......

My INSTANT take is NO...not all drives are a perfect matches..
The older "pre alpha" have a shorter input shaft to the motor than the other models, for example.. I would say that most Gen II drives will as LONG as the gear ratio is correct..The gears for a 120 are 1:95-1 while the V8 (maybe the V6 too) are 1:50-1..

hate to see your top gear box shredded in a few hours.

 

[Don S]

Re: Re-powering a soon to be mine chieftain.

Concidering GM 4.3v6 as replacement for 120 for 165 that exist in chieftains.

Which are you replacing, a 165 or a 120. They are 2 different engines. and the gear ratio in the drive is different for a 120 and not suitable for a V6.

What year is the boat, or the engine you are going to replace?

When you go from an inline engine, to a V type engine, you are adding a big expense.
The V engine (from rapido as an example) is nothing more than a long block, you would have to buy all the other "MARINE" parts for it, things like manifolds and risers, intake manifold, carb, fuel pump, distributor, wiring harness, starter, alternator, brackets to put them on the engine, exhaust y pipe, etc.
Your best bet would be to find a doner boat with the power you want. Then just swap everything over to your starcraft.

If the boat has a 165 inline 6 cylinder engine, stick with it. Those engines are about bullet proof and not worth all the hassle and expense to go to a V6, unless you have a doner boat with a good engine and drive.

 

[reorod]

Re: Re-powering a soon to be mine chieftain.

The boat is a 1974 with a 120 and its a Mercruiser. How dependable are they. No doubt I could rebuild it with all the engine building tricks but I dont know the quirks of this motor and how to increase its durability. Would I be wiser to upgrade to a 165, or a complete doner of newer engine and outdrive. The boat will be completely restored includeing transom work. Love old boats and this is my first boat restoration and I will not get rid of it. Whats the best long-life/service option for my power-plant and drive?

Thanks for the quick response: Mark

 

[Don S]

Re: Re-powering a soon to be mine chieftain.

The boat is a 1974 with a 120 and its a Mercruiser. How dependable are they.

Very dependable if maintained, about like the 165 just less HP. The 2.5 (aka 120) and the 3.0L (aka 140) are probably in more boats than any other engine. But they have to be maintained.
You have a boat that is pushing 40, how has it been maintained over the years, or was it? Have you done a compression test on the engine yet? Probably won't mean much till you actually start it and run it for a few minutes.
Lots of things to look at, at the same time to get it running.
Who knows, the engine and drive may be fine, and not need rebuilding. Engines seldom wear out, they go bad from water and rust and lack of maintenance.

 

[Bondo]

Re: Re-powering a soon to be mine chieftain.

Your best bet would be to find a doner boat with the power you want. Then just swap everything over to your starcraft.

Ayuh,... That's the Best advice you're gonna Get,...
I piece mealed my 74 Islander together,+ with my connectins, it Still woulda been Cheaper to Bone-out a donor boat...

The V6 is a Solid platform,+ makes Great power...
I'd up-date the transom assembley to an Alpha 1, or something from about 81/82 up to a 90...
I think the 83/84 are the most greaseable,... later they started dropping the zerts, 1 by 1...
You'll also have to widen the doghouse,+ build new motor mounts for the V-motor...

Mine was done about 10 years ago,+ it's right around 1200/ 1300hrs. on it now...

I'd say Go for It,...
I'm very Happy with mine...Although absolutely NOTHING is original, other than the tin hull...
And even it has been repaired...

 

[Fishermark]

Re: Re-powering a soon to be mine chieftain.

I think the 83/84 are the most greaseable,....

Ayuh,... to Bond-o that's the most important thing!

 

[CheapboatKev]

Re: Re-powering a soon to be mine chieftain.

Ayuh,... to Bond-o that's the most important thing!

LOL!!! I have pictured Bond-o in an emergency situation saying "GIVE ME THAT BACON GREASE NOW!!!"

 

[reorod]

Re: Re-powering a soon to be mine chieftain.

Nothing has to be original for me, I like the old boat hull with cuddy as is the rest is free game in my opinion. Does heat become an issue with the engine being in a dog house?
My thoughts were to vent the sides of the dog house with down-ward facing leuvers and using an electric exhaust fan like often used in hot rods to draw cool air in from the sides and exhaust through the inside, front of the dog house venting the air to the floor through down-ward facing leuvers. Is this needed or even helpful?

 

[Don S]

Re: Re-powering a soon to be mine chieftain.

LOL!!! I have pictured Bond-o in an emergency situation saying "GIVE ME THAT BACON GREASE NOW!!!"

Ya gotta be kiddin
Bond-o doesn't get caught anywhere without his

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[reorod]

Re: Re-powering a soon to be mine chieftain.

Nice can of grease! lol.

 

[fishinpa]

Re: Re-powering a soon to be mine chieftain.

This part is not necesary with the proper cooling compnents on the engine and functioning .

A fan system like that could also be dangerous in a closed box .
In the event anything ever would flame up the fan would accelerate the fire in your dog box.


fish

 

[reorod]

Re: Re-powering a soon to be mine chieftain.

Reading some of the other post in the forum I see the question was asked about fresh water cooling systems. Is this better than the closed system? Is the fresh water system an older boat setup?

 

[Don S]

Re: Re-powering a soon to be mine chieftain.

Fresh water cooling is better than raw water cooling. It keeps antifreeze on the engines cooling system, and allows a bit higher running temp (175-180?) instead of 160.
In fresh water, it's not a big deal to not have fresh water cooling, in salt water, it's almost a must have to keep the engine in working order.

Is the fresh water system an older boat setup?

Absolutely not, it's used today more than it was in the past.

 

[Bondo]

Re: Re-powering a soon to be mine chieftain.

Nice can of grease! lol.

Ayuh,... Obviously, you ain't been around Long enough to get the Joke,...
It's a Greasy Mess anyways,...
Sorry the guys hy-jacked your thread on ya,...

The over-venting of the doghouse is unnecessary as noted,...
And,..
It's all ready equiped with a bilge blower venting system...

In Michagan,.. Freshwater cooling should be Way Down your wish list,...
Not much Saltwater there...

 

[reorod]

Re: Re-powering a soon to be mine chieftain.

Sorry the guys hy-jacked your thread on ya,...

No problem, always good to laugh Even if a little late!

 

[achris]

Re: Re-powering a soon to be mine chieftain.

Hi,

I looked up the Starcraft's and was surprised how low the maximum power is... My 20' has a maximum of 250hp. I saw the 22' Star has a max of 170hp... My initial reaction on reading your post was that a V6 might be a bit small for a 22'-24', and I was thinking V8... However.... If the Max Hp is so low, how about a Merc 140 (3.0 litre)? It would slip straight into the existing hole of the 120 (2.5 litre), and unless you get a newer exhaust elbow, even the pipe would fit... The leg ratios are the same, the input yoke is the same, the mounting foot print is the same and the engine harness is the same....

Or is that just silly?

Chris........

 

[reorod]

Re: Re-powering a soon to be mine chieftain.

Hi,

i looked up the Starcraft's and was surprised how low the maximum power is... My 20' has a maximum of 250hp. I saw the 22' Start has a max of 170hp... My initial reaction on reading your post was that a V6 might be a bit small for a 22'-24', and I was thinking V8... However.... If the Max Hp is so low, how about a Merc 140 (3.o litre)? It would slip straight into the existing hole of the 120 (2.5 litre), and unless you get a newer exhaust elbow, even the pipe would fit... The leg ratios are the same, the input yoke is the same, the mounting foot print is the same and the engine harness is the same....

Or is that just silly?

Chris........

I,m on the learning level for repowering a boat and all info is valued. No its not silly, sounds good

 

[elkhunter338]

Re: Re-powering a soon to be mine chieftain.

I new 2007 140hp will push a 21 chieftain loaded with fishing gear, fuel, and 4 full size guys all 200+ lbs, with 25hp kicker on the back at about 25mph wot @ 4,000 rpms.
It cruises good at 20 mph @ 2900rpms.
so for fishing the little 4 banger is great, no water ski boat, does pretty good on fuel and troll all day long on a few gallons of gas.
My 1986 cheiftain has a 2007 135hp crate motor in it. The reason was because some guy put a 1971 merc. 140 motor and outdrive in the boat and then I lost a timing gear on the old engine and replaced it with a new one.

 

[Bondo]

Re: Re-powering a soon to be mine chieftain.

Or is that just silly?

Ayuh,... Of Course it is,....Who ever heard of Too Much Horsepower...

My ole 74, with the 205hp, 4.3LX will poke along at 43mph, at 4800rpms... In Freshwater..
52mph in the Saltwater off Maine...
With the 140hp I took out it did 28mph...

And, That's a fully outfited Fishin' machine....