470 swap to 4.3

[Scott Danforth]

I called Green Bay prop regarding a 305 I saw they had listed online… no 4.3’s…. I’m not sure if that would even be an option but would be nice to have the hp. Are you from wi? Any recommendations on mechanics I could reach out to for this kind of work? As mentioned a few I spoke to we’re not to thrilled about it….

Yes, from WI.

You probably won't find anyone to do the work.

If you do, expect to pay about $4k

 

[Winterd03]

Yes, from WI.

You probably won't find anyone to do the work.

If you do, expect to pay about $4k

Yes, from WI.

You probably won't find anyone to do the work.

If you do, expect to pay about $4k

Thanks! This is the first ballpark number I got on it - If I find the right motor, more hp, and able to find someone willing to do it I think that would be worth it. Cheers

 

[stresspoint]

OP ,not quite where you are at but i will share my experience with you and others on the forum.

i bought a Maxum SR 1800 a while back , the hull was for the most part in very good condition and it was a match for my needs as a smallish family cruiser .
the 4.3 motor was knackered with a split bore (common issue i believe with 4.3 engine blocks).
my drive alpha 1 gen 2 with 1.8 ratio was in near perfect condition.

i chased down a complete supposedly " running when removed ' earlier model 1988 4.3 assembly to bolt in place , which would have been a perfect option had it been "as advertised". Word of warning ! ,if you choose to just replace what you have with a used assembly , """""don't trust seller to know what they are selling"" , have the entire assembly inspected by someone competent before forking over cash and going to the effort to gain owner ship IE shipping etc.
(long story but not for now ).

i was now in a situation where i had >
a dead motor in the boat less 1 head and a cracked block , a motor i had bought that was going to take more work than practicality would allow .
i have a early 350 SB in the shed that needed a complete exhaust and all the other stuff to convert a hull that was meant for a 4.3 to go to a V8 which can be costly without buying another complete Mercruiser set up for a V8 so as it could be adapted .

long story short ,
i built myself a beautiful 4.3 V6 utilizing as many later model parts i could muster , as many performance bits as was practical "costly yes, however i now have a boat that my family has so far had lots of time on without issues.

I'm not sure if i am allowed to link threads from THT here but i did a complete go to woe of how i got to this point ( giving it some much deserved love restoration thread ) MODS,, feel free to delete that kind of link if it is in appropriate on this forum, i am not 100% on the forum rules yet .

i hope this post will help OP or others on a decision whether or not to do a conversion , replace with used assembly , rebuild the set up what he has with a later model set up .

 

[Scott Danforth]

Thanks! This is the first ballpark number I got on it - If I find the right motor, more hp, and able to find someone willing to do it I think that would be worth it. Cheers

The $4k is just labor (shop rate). That is assuming you find a motor

 

[Winterd03]

The $4k is just labor (shop rate). That is assuming you find a motor

 

[Winterd03]

Appreciate everyone’s feedback - thank you!

 

[nola mike]

Hey... @nola mike

Yeah, so the power increase with the 4.3 hasn't been very impressive. Given that I still may not have it dialed in correctly--it certainly should be a big bump. Top end I get maybe 1 mph. Pulling me up on a slalom isn't as strong as I had hoped--weight penalty on a small boat is big. Granted, I still don't think I'm totally dialed in, and am planning on getting a wideband O2 sensor in the spring. That said, with all the work involved, if your boat can handle it, get a 350. I still don't understand the point of a 305, or why they exist. You might need a new outdrive, but that's not a big deal. You can find a used 1.5 easy, and sell yours if needed. I wouldn't consider a swap without a donor boat unless you get a bobtail engine. Too many little things that are hard to find/$$$ when purchased separately. Carb/brackets (although I think the 190 had a Weber that you could rejet?), ignition, starter, alt/brackets, hoses, exhaust pieces, etc.

 

[QBhoy]

Also need to change the mounts for the engine. New mounts need to be glasses in to take the 4.3.