87’ invader mercruiser help me ! 👸

[Aido_05]

Help a girl out . I have a 87’invader boat . Inboard?/outboard ? . Boat size is 19’-21’feet in size . The current motor in there now is a mercruiser 190 . I just picked up a good working mercruiser V8 4.3L. Will this FIT my boat ?anybody know ? (I’m told some mounting fabrication can be easily done ) but for size .. should this physically fit this model?

 

[markhodges78]

For starters that’s a V6 not a V8 the out drive would need to be changed as well as the exhaust y. You would also need to add mount pads in the boat

 

[Aido_05]

For starters that’s a V6 not a V8 the out drive would need to be changed as well as the exhaust y. You would also need to add mount pads in the boat

Thank you

 

[Bondo]

Ayuh,...... Welcome Aboard,.......

That's a 470, I-4, the gear ratio will be just fine,....
You will need a Y-pipe, 'n related exhaust parts,....
You'll probably have to widen the doghouse, 'n you'll need to build motor mounts to hold the V-motor,.....
There'll also be some plumbin', wirin', 'n what-nots that'll need fabricatin',....

All told, the 4.3l is a fine swap for an ole 470,....
with a 4bbl. carb a solid 205 horsepower or more,.....

 

[Aido_05]

Ayuh,...... Welcome Aboard,.......

That's a 470, I-4, the gear ratio will be just fine,....
You will need a Y-pipe, 'n related exhaust parts,....
You'll probably have to widen the doghouse, 'n you'll need to build motor mounts to hold the V-motor,.....
There'll also be some plumbin', wirin', 'n what-nots that'll need fabricatin',....

All told, the 4.3l is a fine swap for an ole 470,....
with a 4bbl. carb a solid 205 horsepower or more,.....

Thanks ,I appreciate the detail . This is another language to me but I’ve passed it on to a mechanical engineer friend of mine . I was pumped to find this working “V6” for 500$ Canadian and think I’ve hit the jackpot .. and all my boat guy can say was nothing encouraging or hopeful . But he did say ... “err , well ... err,, maybe ... kinda , parts , and then said I have a whole different system ect ect” . He’s already given me a new starter , a new carb piece , and cleaned the carburetor apparently .. and 2000$ later .. finally does a oil change , sees milky oil (water) and finds a cracked block ... after he knew it had been sitting for four years untouched and I said I had no idea if it had been winterized or Not .

so I appreciate the input .
First boat license , first family boat given to me , I’ve just learnt to drive with the trailer . I’m a chick and a easy target to take advantage of likely . I’ll probably be pulling it out of there to another garage , this guy isn’t giving me the confidence he has the skill .

 

[nola mike]

What's wrong with the current motor? I would *highly* recommend against this swap. It is not easy and takes a decent amount of know how to accomplish. Whatever is wrong with your current setup, it would almost certainly be a better idea to fix what you have. Besides, you have a pretty rare beast with the 4bbl carb. I don't think you'd gain enough with the 4.3 to make it worthwhile

Edit: saw cracked block. This is almost unheard of in these engines. They run antifreeze through the block

 

[Aido_05]

What's wrong with the current motor? I would *highly* recommend against this swap. It is not easy and takes a decent amount of know how to accomplish. Whatever is wrong with your current setup, it would almost certainly be a better idea to fix what you have. Besides, you have a pretty rare beast with the 4bbl carb. I don't think you'd gain enough with the 4.3 to make it worthwhile

Edit: saw cracked block. This is almost unheard of in these engines. They run antifreeze through the block

Well as far as we know the staff that was using it got fired mid summer four years ago (everything on it was working perfect before that) .. I don’t know if it was ever winterized at all .it’s sat for four years. I inherited it after that. (Just to be clear, I know nothing about boats ). I’m in kenora Ontario Canada -35 winters ..I’m pretty sure that can crack anything .
Either way . I took this to the place last august last year in hopes of a “assessment” to see if it would be worth putting the money into . With the knowledge it was sitting for four years ... the key wouldn’t turn . Enter : new starter , impeller piece, water pump thing ?, engine fires up right away ... he says he let it run on the rabbit ears for 10 minutes or so .. and it shut itself off . Assuming it wasn’t getting enough water to cool it down perhaps ?.
I thought it was ODD that it was at this point he offers up a oil change (seems like a pretty preliminary thing to do when a motor is sitting for four years ?) ...and tells me the oil change is “milky” implying water dilution in the oil .... it’s at this point when he takes a bunch of parts off my motor in there , sends me some rusty photos and tells me water is getting in somewhere or a crack of some sort ?. I didn’t physically see the crack ?., but I saw rusty parts and seems fitting for a boat that was likely not winterized. so I never questioned that .
as far as the power is concerned the original owner (there has only been one .. my uncle ) says that boat could always use a little more power . 2 of my friends (mechanical engineer) and (John Deere electrical tech) have said the same thing ..that the power of this new one would be sweet ...or so they say .

Quote: “ahhh ... They make custom **** like that every day. Guy sounds like a loser who doesnt wanna get off his ass and take on a challenge”
Thats a perfect opportunity to make a through-hull exhaust system!”
(This of course is Chinese to me.hah)

 

[nola mike]

Ok. You won't gain much in power with the swap. In fact, depending on how that v6 is set up you might lose power. Also it sounds like a) you'd be in over your head and b) you don't have anyone who knows wtf they're doing. You would need a *complete* v6 with all the accessories. You would need to fiberglass in new motor mounts. imo you're better off looking for a new 3.7l block (or verifying that yours is cracked--they don't need to be winterized really). This is not a cost effective swap even if you do all the work yourself.

 

[Aido_05]

Ok. You won't gain much in power with the swap. In fact, depending on how that v6 is set up you might lose power. Also it sounds like a) you'd be in over your head and b) you don't have anyone who knows wtf they're doing. You would need a *complete* v6 with all the accessories. You would need to fiberglass in new motor mounts. imo you're better off looking for a new 3.7l block (or verifying that yours is cracked--they don't need to be winterized really). This is not a cost effective swap even if you do all the work yourself.

Thanks for your input , I appreciate it . Yup I’m in Over my head , but I’ll find somebody who’s not , I’m determined . I’m not worried about spending a couple grand more , I’m trading dock rental space for boat fixing budget . but yeah I just need something to work . maybe the new shop will take a look at the old one first to confirm . Thanks .

 

[achris]

Thats a perfect opportunity to make a through-hull exhaust system!”

Don't! You'll love it for about 5 minutes, then it'll be nothing but headache inducing. Very VERY few people who go down the 'thru-hull exhaust' route don't regret it. And usually sooner rather than later. If you REALLY want it, then make sure you install a switchable system (switchable between thru-hull and thru-prop), something like 'Captain's choice', or 'Silent Choice'.

The drive is fine to use. The V6 and the 190 (which is what is referred to as a '470') use the same ratio (1.84:1). The V6 will have much better mid range power than the 190. And as from 1983, all drives use the same input yoke.

The 190 is just a 4 bbl carb version of the 470, and as such suffers from low- and mid-range power, mostly due to having to wear a taller propeller to reign in rpm at the top end. (read my thread on the 'benefits' of more power)...

The 470 to V6 conversion is not as smooth as you would think, but is you have mechanic friends who are willing to listen and ask questions before blundering in, then with the help of some truly amazing people on this forum you'll 'get er done'...

Chris.........

 

[nola mike]

The 190 is just a 4 bbl carb version of the 470, and as such suffers from low- and mid-range power, mostly due to having to wear a taller propeller to reign in rpm at the top end. (read my thread on the 'benefits' of more power)...

I'll disagree with you on this one. I still haven't noticed a *huge* increase in power, although the v6 is much smoother and the power is effortless mid-range, I'm not usually looking to accelerate quickly from 25-40 knots. I want it down low, and I think the 200# weight penalty of the v6 hurts vs. the 3.7. And that's going from a 170 hp to a vortec 4bbl v6. Going from the 4bbl 3.7 to a 2bbl pre vortec v6 would be less impressive. Interesting about the carb though. There must be a benefit to a 4bbl carb in a boat. Wouldn't have been used otherwise. I would LOVE to see torque curves for these engines. Never have.

The 470 to V6 conversion is not as smooth as you would think, but is you have mechanic friends who are willing to listen and ask questions before blundering in, then with the help of some truly amazing people on this forum you'll 'get er done'...

Chris.........

That is very true!

 

[Rick Stephens]

I did a similar swap.... and enjoyed it. It required fabricating new engine mounts, and disassembly of almost everything, and learning how every last piece works together. Both me and the boat are better for it. Was it financially reasonable, probably not. But for me, it was fun and the V6 is so much quieter and smoother running than the inline 4.

However, to make that happen, I had a fully complete motor, transom and drive to pull out of a rotted boat and installed every last piece in my boat. Rebuilding, resealing, repainting all the parts of the motor and drive, running the motor on a pallet before installing and all sorts of fiberglass time.

Depends on what you want to spend your spring and summer on.

 

[achris]

I'll disagree with you on this one. I still haven't noticed a *huge* increase in power, although the v6 is much smoother and the power is effortless mid-range, I'm not usually looking to accelerate quickly from 25-40 knots. I want it down low, and I think the 200# weight penalty of the v6 hurts vs. the 3.7. And that's going from a 170 hp to a vortec 4bbl v6. Going from the 4bbl 3.7 to a 2bbl pre vortec v6 would be less impressive. Interesting about the carb though. There must be a benefit to a 4bbl carb in a boat. Wouldn't have been used otherwise. I would LOVE to see torque curves for these engines. Never have.

OK, we may agree to disagree on this one. (and I was referring to a 190, not a 470, the differences I will explain)...

I agree with regard to the weight penalty, and that will have an affect on acceleration, but that can be alleviated with a propeller change. I have recently changed from a 3 blade to a 4 blade propeller, and the difference is stunning. The extra stern lift with the 4 blade will somewhat offset the extra engine weight.

As for the power, with reference to my post on increasing topend power, an increase in engine power by only the addition of a 4bbl carb is very much in line with that post. That increase of power is at the top end, the low and mid-range power is exactly the same (same engine, including camshaft, head and spark timing, just a bigger carb), but with the extra ponies at the pointy end, a bigger prop is needed to keep the revs in check when the hammer gets dropped, and that tends to knee-cap the engine in the low and mid-range. I would even venture to suggest that a 470 will outperform a '190' in an acceleration test (due to the bigger prop the 190 would have to wear to stay in the recommended range). And if you were to put the same prop on a 470 and a 190, up to the point where the 190 is making 170hp, they would preform exactly the same.

Cheers,

Chris....