1987 Merc 4.3 Rebuild or replace?

[timharper89]

Long story short, my 1987 Four Winns Sundowner 195 developed a knock/rattle this summer when it ran low on oil (for more on that, see my other thread). My wife and I are contemplating cutting our losses as we were considering buying something a bit newer and more in the 23 foot range (really like the layout of the rinker captiva 232 cc or regal 6.8 ventura around the year 2000), but our budget is a little limited, and we may end up a season without a boat while waiting for the right deal to come along. The hull seems to be sound (floors feel solid, no flex in the transom and the stringers feel solid), so I was considering attempting to rebuild the engine myself. I tried looking around without much luck of finding how much rebuilding the engine myself would cost vs buying a long block. My wife is concerned about taking such a risk (I mess it up somehow, and now we're out $XXX instead of just cutting our losses and selling the boat as is, but I'm thinking rebuilding could be a low cost option to get us by for a few more years and allow us to casually look for the right boat instead of just wanting to be on the water again and making compromises for short term happiness.

The boat has been sluggish since we bought it 4 years ago and fully loaded with 6 adults and 2 kids (only that full once or twice a year) can take VERY long to plane out....like a full minute or more (propped correctly with 4 blade alum prop for 4400rpm @ WOT), and topped out at 33mph gps with 3 adults on board. It has had one cylinder with blowby since we bought it. Would rebuilding give the motor more oomph? Would it be likely to feel a significant increase in performance, namely hole shot?

TLDR: What is a ball park figure for rebuilding my own engine? (Parts and machining, etc.) and how much would I save vs buying a rebuilt long block for just under $2k shipped?
Will I see decent power increase from previously running with one cylinder with low (100psi<other cylinders) compression?
I have the engine shop manual. What other resources and tools beyond standard tools would be required for this job?
A boat this old, should I just cut my losses and look for something new or is it worth hanging onto for a few more years while we casually look for the right boat within our relatively low budget? Thanks for any info.

 

[nola mike]

Long story short, my 1987 Four Winns Sundowner 195 developed a knock/rattle this summer when it ran low on oil (for more on that, see my other thread). My wife and I are contemplating cutting our losses as we were considering buying something a bit newer and more in the 23 foot range (really like the layout of the rinker captiva 232 cc or regal 6.8 ventura around the year 2000), but our budget is a little limited, and we may end up a season without a boat while waiting for the right deal to come along. The hull seems to be sound (floors feel solid, no flex in the transom and the stringers feel solid), so I was considering attempting to rebuild the engine myself. I tried looking around without much luck of finding how much rebuilding the engine myself would cost vs buying a long block. My wife is concerned about taking such a risk (I mess it up somehow, and now we're out $XXX instead of just cutting our losses and selling the boat as is, but I'm thinking rebuilding could be a low cost option to get us by for a few more years and allow us to casually look for the right boat instead of just wanting to be on the water again and making compromises for short term happiness.

The boat has been sluggish since we bought it 4 years ago and fully loaded with 6 adults and 2 kids (only that full once or twice a year) can take VERY long to plane out....like a full minute or more (propped correctly with 4 blade alum prop for 4400rpm @ WOT), and topped out at 33mph gps with 3 adults on board. It has had one cylinder with blowby since we bought it. Would rebuilding give the motor more oomph? Would it be likely to feel a significant increase in performance, namely hole shot?

TLDR: What is a ball park figure for rebuilding my own engine? (Parts and machining, etc.) and how much would I save vs buying a rebuilt long block for just under $2k shipped?
Will I see decent power increase from previously running with one cylinder with low (100psi<other cylinders) compression?
I have the engine shop manual. What other resources and tools beyond standard tools would be required for this job?
A boat this old, should I just cut my losses and look for something new or is it worth hanging onto for a few more years while we casually look for the right boat within our relatively low budget? Thanks for any info.

This is the wrong time to buy a boat. Your performance is way off, my similar boat (granted 4bbl carb and vortec heads) has no problem getting on plane, even with 5 adults 4 kids on board, and can hit 44 mph with that load. 2k for a rebuilt long block is pretty good. Doing it yourself (plus machine work?) Would probably be 1-2k. Your boat has no value with a bad engine.

 

[achris]

Long story short, my 1987 Four Winns Sundowner 195

Don't really care what the boat is, tell us about the engine. (serial number and model is a good place to start)

developed a knock/rattle this summer when it ran low on oil (for more on that, see my other thread). My wife and I are contemplating cutting our losses as we were considering buying something a bit newer and more in the 23 foot range (really like the layout of the rinker captiva 232 cc or regal 6.8 ventura around the year 2000), but our budget is a little limited, and we may end up a season without a boat while waiting for the right deal to come along.

Trying to sell a boat without a good engine will be like giving the boat away. Regardless of what you decide, getting a running engine in the boat to sell it is the only way you'll get anything for it.

The hull seems to be sound (floors feel solid, no flex in the transom and the stringers feel solid), so I was considering attempting to rebuild the engine myself.

Buy a stock truck engine (from a wrecker's yard), replace the head gaskets and core plugs, and you have a marine long block. Transfer all the fruit and veg from the dead block, (including the engine serial number plate!) and you have a working engine in the boat.

What you do need to do is learn about all the variants of the V6. Balance shafts, vortec heads, tin/composite timing cover, etc. Then you can make informed decisions and get the job done without any unforeseen 'oops'...

I tried looking around without much luck of finding how much rebuilding the engine myself would cost vs buying a long block. My wife is concerned about taking such a risk (I mess it up somehow, and now we're out $XXX instead of just cutting our losses and selling the boat as is,

Sell it 'as is' and you'll get nothing for it.

but I'm thinking rebuilding could be a low cost option to get us by for a few more years and allow us to casually look for the right boat instead of just wanting to be on the water again and making compromises for short term happiness.

Agreed.

The boat has been sluggish since we bought it 4 years ago and fully loaded with 6 adults and 2 kids (only that full once or twice a year) can take VERY long to plane out....like a full minute or more (propped correctly with 4 blade alum prop for 4400rpm @ WOT),

No, no, no... 4400 at WOT it too low, way too low. The recommended range is 4400-4800, and without putting any extra load you're already right at the bottom of the range. I prop for the top of the range, and consider even up to 200rpm above as completely acceptable.

and topped out at 33mph gps with 3 adults on board. It has had one cylinder with blowby since we bought it. Would rebuilding give the motor more oomph? Would it be likely to feel a significant increase in performance, namely hole shot?

No, you'll just be getting back to where you were. To improve performance you will need to drop the prop pitch by 2" (if you're running a 21" now, drop to 19")

TLDR: What is a ball park figure for rebuilding my own engine? (Parts and machining, etc.) and how much would I save vs buying a rebuilt long block for just under $2k shipped?
Will I see decent power increase from previously running with one cylinder with low (100psi<other cylinders) compression?

Not really. HP isn't the only number you should be looking at.

I have the engine shop manual. What other resources and tools beyond standard tools would be required for this job?

Depends on exactly how much work and what changes you'll be making.

A boat this old,

Old? Who are you kidding! Look at my boat (in the forum signature below), and I would NEVER consider it to be 'too old'. A good hull is a rarity these days... If you have one, you keep it going!

should I just cut my losses and look for something new

Anything 'newer' is not going to be of the same quality. In the last 20 or 30 years, manufacturers (of everything) have refined their ability to make goods that last EXACTLY how long they want them too. Look at washing machines. My washing machine is from the 1980s, and all I have replaced on it is the water pump. I have friends who are replacing their 'new' machines every 5 to 7 years. Meanwhile, my 40 year old machine just keeps on keeping on.

So here's what I would be looking at. Now, I'm going to make some assumptions here, based on a lack of information. (A '1987 4.3' doesn't tell us a lot).
If you have fluid mounts, then it's a non-balance shaft engine. 2 ways we can go here. Stay with a non-balance shaft engine and either try to find a 'wrecker special' to replace it. And with that I would consider dropping a couple of vortec heads, a 4 bbl manifold and an Edelbrock 1409 carb on. That should get you in the region of 210hp, and a lot better mid range power. If a non-balance shaft truck engine can't be found, you might need to find a machine shop to rebuild the existing short block.
If you don't have fluid mounts, or do and want to get a balance shaft engine, find a later model truck engine and marinize it (head gaskets and core plugs). A late model engine (post 1997) will have vortec heads. You might need to find an iron manifold for it though (or a marine aluminium).

Whatever you decide, ask here, all the time. There are no silly questions, just dumb f-ups becasue you didn't ask questions. ;-)

Good luck,

Chris.....

 

[timharper89]

Don't really care what the boat is, tell us about the engine. (serial number and model is a good place to start)

Thanks for the detailed response! I forgot the top of the serial number. s/n 0B459735. Not sure what you mean by model number. It's says "185" on the flame arrestor cover. Pretty sure when I looked it up for parts on catalogue it was only made in the year 1987.

Trying to sell a boat without a good engine will be like giving the boat away. Regardless of what you decide, getting a running engine in the boat to sell it is the only way you'll get anything for it.

Yeah I figured. We bought it for $2100 4 summers ago to figure out if we were boat people. It has certainly given me an understanding of how much work a boat can be (boat was sinking or first use due to bad bellows, carb was flooding due to impetuous fuel pump pressure replaced steering cable, put lights and needed new tires on the trailer, etc.) but we decided we really are boat people despite the work. However, given the price I paid, getting nothing for it would still be worth what I paid vs the use we've gotten. But I'm a bit partial now as I have grown attached to my first boat and the work and care I have put into it.

Buy a stock truck engine (from a wrecker's yard), replace the head gaskets and core plugs, and you have a marine long block. Transfer all the fruit and veg from the dead block, (including the engine serial number plate!) and you have a working engine in the boat.

I have the option of getting a used (unknown condition) long block 4.3 merc from a guy who sells boat parts for $650. Given it is a boat engine with maybe a harder life, would the truck engine still be a better option? Also what does age of the truck and how long is been sitting mean? We use fogging oil to coat the inside of the block to stop it from rusting from condensation. An engine in the junk yard doesn't have this protection. What does that mean for the condition of whatever in going to pull out?

What you do need to do is learn about all the variants of the V6. Balance shafts, vortec heads, tin/composite timing cover, etc. Then you can make informed decisions and get the job done without any unforeseen 'oops'...

Seems there is always some education needed. Exhausting, but someday I'll use the information a second time...maybe

No, no, no... 4400 at WOT it too low, way too low. The recommended range is 4400-4800, and without putting any extra load you're already right at the bottom of the range. I prop for the top of the range, and consider even up to 200rpm above as completely acceptable.

I think it is 4600. I haven't rechecked it in a while, but when I put the new prop on (P. O. had a 23 pitch on) I had it set right on the middle. Assuming my tach is accurate. It SOUNDS accurate to me, but that's not scientific at all.

No, you'll just be getting back to where you were. To improve performance you will need to drop the prop pitch by 2" (if you're running a 21" now, drop to 19")

So I won't get any more power from firing properly on all 6 cylinders? I'm currently running a 19x14.5 4 blade prop

Depends on exactly how much work and what changes you'll be making.

I was leaning toward a rebuild when I posted this, but not sure now. More power sounds nice as that was it biggest complaint about the boat. We like to ski occasionally, and I'm the only one who can get up because it takes so long to plane the boat. If I'm not going to get more power rebuilding, and it would be cheaper replacing, then I'm definitely open to that.

Old? Who are you kidding! Look at my boat (in the forum signature below), and I would NEVER consider it to be 'too old'. A good hull is a rarity these days... If you have one, you keep it going!

It does seem a shame to waste the boat. Maybe just die to my attachment, but it's been great for us.

Anything 'newer' is not going to be of the same quality. In the last 20 or 30 years, manufacturers (of everything) have refined their ability to make goods that last EXACTLY how long they want them too. Look at washing machines. My washing machine is from the 1980s, and all I have replaced on it is the water pump. I have friends who are replacing their 'new' machines every 5 to 7 years. Meanwhile, my 40 year old machine just keeps on keeping on.

I hear you there. We have been looking at things in the late 90s/early 00s. This boat isn't going to be our forever boat due to its size and seating limitations. There are several other things not perfect as well. It's missing a window, one of the seats was rotted and broken, a screw on the swim platform is stripping out, and there are things I need to fix on the trailer.

So here's what I would be looking at. Now, I'm going to make some assumptions here, based on a lack of information. (A '1987 4.3' doesn't tell us a lot).
If you have fluid mounts, then it's a non-balance shaft engine. 2 ways we can go here. Stay with a non-balance shaft engine and either try to find a 'wrecker special' to replace it. And with that I would consider dropping a couple of vortec heads, a 4 bbl manifold and an Edelbrock 1409 carb on. That should get you in the region of 210hp, and a lot better mid range power. If a non-balance shaft truck engine can't be found, you might need to find a machine shop to rebuild the existing short block.

ATM not sure what the difference in balanced and non balanced is, but what is a wrecker special? How would I know if the truck is balanced or non balanced? Vortec heads but not intake? Why did I think the carb was 2bbl or 4 bbl instead of the intake?

If you don't have fluid mounts, or do and want to get a balance shaft engine, find a later model truck engine and marinize it (head gaskets and core plugs). A late model engine (post 1997) will have vortec heads. You might need to find an iron manifold for it though (or a marine aluminium).

I don't need to use different cams? I've read that is important when marinizing an engine. I knew the exhaust manifolds needed to be native, but I didn't realize intake did. Are the bolt on accessories (alt, ps, water) going to be different? Will these newer motors just be plug and play?

Whatever you decide, ask here, all the time. There are no silly questions, just dumb f-ups becasue you didn't ask questions. ;-)

Good luck,

Chris.....

I appreciate it. I over think everything, so I ask a lot of questions.

 

[timharper89]

This is the wrong time to buy a boat.

I've noticed. Everyone wants a fortune for their boats right now.

Your performance is way off, my similar boat (granted 4bbl carb and vortec heads) has no problem getting on plane, even with 5 adults 4 kids on board, and can hit 44 mph with that load.

I was thinking it was off. Most people I had read about were hitting close to 40mph at wot

2k for a rebuilt long block is pretty good. Doing it yourself (plus machine work?) Would probably be 1-2k.

What determines how much diy is? The machine shop? I guess I just figured rebuilt would be kind of standard in parts needed. Any reason I would need more or fewer parts?

 

[Lou C]

Scott posted up a listing of all the changes made in the 4.3s, there are many. The best thing to do is find the block casting # which is behind the starboard side cyl head on the rear end of the block and the cyl head casting #s which are visible when you remove the valve covers. The # you can see on the starboard side of the front of the block is the GM serial number; these will start with a T for the Tonawanda assembly plant in NY or an R for the Romulus assembly plant in Michigan. This matters too because there are small but important differences in engines built in these 2 plants.

 

[Lou C]

PS as far as rebuilding this yourself well a lot depends on your level of experience, tools, engine lifting equipment & stand etc. A proper rebuild will require disassembly, cleaning, measuring everything for wear magnafluxing the cyl heads, etc. You will have to work with a good automotive machine shop to get some of these steps done. If you have never rebuilt an engine before this is a big and complex project. If I were you I’d find a machine shop take the engine to them and see if it’s rebuildable. The parts for these engines are cheap & available and properly built & maintained they will last 15-20 years in a boat that size. If in good shape with a 4 bbl carb that should have enough power for a boat that size. You can also swap to a later Vortec V6 with the balance shaft and it will run smoother and put out approx 225 hp with the 4bbl carb.

 

[Lou C]

Here's a pic of the Vortec 4.3 with the locations of the casting #s and GM serial #.
Mercruiser also puts a tag with their own ID above where the starter is mounted.
The reason why the #s are important, is with a 1987 boat, you could have a 1986 or 1987 production engine. It makes a difference because in '86 they went to the one piece rear main seal, but still has flat tappet cam & hydraulic lifters, in '87 they changed to the roller cam and roller lifters. You can stay with the older series with no balance shaft, if its got the roller cam and lifters that's a plus because they seem to wear less, and stick with the original pre-vortec heads or add a pair of vortec heads and intake to pick up 25 hp. But once you get into the internals like the crank/rods etc, you have to know exactly what your're doing because there are differences there between the years and between the Tonawanda and Romulus production. I THINK I remember reading somewhere that the marine engines all came from Tonawanda but not sure, if you get one from a salvage yard that was in a Chevy or GMC truck it could have come from either.

 

[tank1949]

Long story short, my 1987 Four Winns Sundowner 195 developed a knock/rattle this summer when it ran low on oil (for more on that, see my other thread). My wife and I are contemplating cutting our losses as we were considering buying something a bit newer and more in the 23 foot range (really like the layout of the rinker captiva 232 cc or regal 6.8 ventura around the year 2000), but our budget is a little limited, and we may end up a season without a boat while waiting for the right deal to come along. The hull seems to be sound (floors feel solid, no flex in the transom and the stringers feel solid), so I was considering attempting to rebuild the engine myself. I tried looking around without much luck of finding how much rebuilding the engine myself would cost vs buying a long block. My wife is concerned about taking such a risk (I mess it up somehow, and now we're out $XXX instead of just cutting our losses and selling the boat as is, but I'm thinking rebuilding could be a low cost option to get us by for a few more years and allow us to casually look for the right boat instead of just wanting to be on the water again and making compromises for short term happiness.

The boat has been sluggish since we bought it 4 years ago and fully loaded with 6 adults and 2 kids (only that full once or twice a year) can take VERY long to plane out....like a full minute or more (propped correctly with 4 blade alum prop for 4400rpm @ WOT), and topped out at 33mph gps with 3 adults on board. It has had one cylinder with blowby since we bought it. Would rebuilding give the motor more oomph? Would it be likely to feel a significant increase in performance, namely hole shot?

TLDR: What is a ball park figure for rebuilding my own engine? (Parts and machining, etc.) and how much would I save vs buying a rebuilt long block for just under $2k shipped?
Will I see decent power increase from previously running with one cylinder with low (100psi<other cylinders) compression?
I have the engine shop manual. What other resources and tools beyond standard tools would be required for this job?
A boat this old, should I just cut my losses and look for something new or is it worth hanging onto for a few more years while we casually look for the right boat within our relatively low budget? Thanks for any info.

I feel your pain! U are not real clear on motor size or environment. Is it a salt water boat? Scrap VERY OLD motor... With motor out, examine transom/stringers for rot. If rot found, expect lots of personal work or thousands $$$ more spent just getting hull safe, plus added motor expenses. Trust me! Usually LBs come with guarantee, although not much. So, plan on installing LB in the spring to have time to test it before warrantee expires.. Locally, we can get a 350 reman for under 2 grand, but then you will need (most likely) new exhaust and risers. U have a lot of variables to consider and if you buy another used boat, you will most likely have the same variables to consider. I have been restoring a 1986 SR AJ since 2016, but heath and Covid delays have cause more issues. However, when I get through, everything will be to my satisfaction and I will have a warm fuzzy feeling when I am 100 miles offshore. Good luck

 

[timharper89]

Scott posted up a listing of all the changes made in the 4.3s, there are many. The best thing to do is find the block casting # which is behind the starboard side cyl head on the rear end of the block and the cyl head casting #s which are visible when you remove the valve covers. The # you can see on the starboard side of the front of the block is the GM serial number; these will start with a T for the Tonawanda assembly plant in NY or an R for the Romulus assembly plant in Michigan. This matters too because there are small but important differences in engines built in these 2 plants.

I read through that, but it seems mostly relevant if you are trying to change over internals between models. Am I wrong here? If I buy a long block, how much does it matter that the internals are different? I see the heads and intake might be different, but what else is relevant to swapping a long block? The cam bearing differences if I have to swap the cam?

PS as far as rebuilding this yourself well a lot depends on your level of experience, tools, engine lifting equipment & stand etc. A proper rebuild will require disassembly, cleaning, measuring everything for wear magnafluxing the cyl heads, etc. You will have to work with a good automotive machine shop to get some of these steps done. If you have never rebuilt an engine before this is a big and complex project. If I were you I’d find a machine shop take the engine to them and see if it’s rebuildable. The parts for these engines are cheap & available and properly built & maintained they will last 15-20 years in a boat that size. If in good shape with a 4 bbl carb that should have enough power for a boat that size. You can also swap to a later Vortec V6 with the balance shaft and it will run smoother and put out approx 225 hp with the 4bbl carb.

I am fairly competent, if not super experienced. I took an auto service course at a tech school in high school (12 years ago) and did rebuild an engine during that time, but it was a long time ago, so I really don't remember the whole process. It would be a big accomplishment to rebuild the motor myself, but my main concern for now is cost, mostly because my wife doesn't want to gamble too much. If I can swap motors for cheaper and still expect (I understand there are no guarantees) several more years out of it until we upgrade, then I am definitely open to that.

Here's a pic of the Vortec 4.3 with the locations of the casting #s and GM serial #.
Mercruiser also puts a tag with their own ID above where the starter is mounted.
The reason why the #s are important, is with a 1987 boat, you could have a 1986 or 1987 production engine. It makes a difference because in '86 they went to the one piece rear main seal, but still has flat tappet cam & hydraulic lifters, in '87 they changed to the roller cam and roller lifters. You can stay with the older series with no balance shaft, if its got the roller cam and lifters that's a plus because they seem to wear less, and stick with the original pre-vortec heads or add a pair of vortec heads and intake to pick up 25 hp. But once you get into the internals like the crank/rods etc, you have to know exactly what your're doing because there are differences there between the years and between the Tonawanda and Romulus production. I THINK I remember reading somewhere that the marine engines all came from Tonawanda but not sure, if you get one from a salvage yard that was in a Chevy or GMC truck it could have come from either.

I don't plan on messing with the internals if I replace with a long block. Is that not a realistic expectation? Buy the block, swap the intake, head gasket, exhaust manifold, and maybe cam and call it a day, right? Either way I go, I don't want to mess with changing the internals around if it isn't necessary.

 

[timharper89]

I feel your pain! U are not real clear on motor size or environment. Is it a salt water boat? Scrap VERY OLD motor... With motor out, examine transom/stringers for rot. If rot found, expect lots of personal work or thousands $$$ more spent just getting hull safe, plus added motor expenses. Trust me! Usually LBs come with guarantee, although not much. So, plan on installing LB in the spring to have time to test it before warrantee expires.. Locally, we can get a 350 reman for under 2 grand, but then you will need (most likely) new exhaust and risers. U have a lot of variables to consider and if you buy another used boat, you will most likely have the same variables to consider. I have been restoring a 1986 SR AJ since 2016, but heath and Covid delays have cause more issues. However, when I get through, everything will be to my satisfaction and I will have a warm fuzzy feeling when I am 100 miles offshore. Good luck

Motor size is 4.3L and fresh water only. I think any structural work is beyond what I want to tackle and would sooner scrap the boat, but everything seems fine structurally at the moment. It's definitely not perfect, but it is adequate for us for now.

 

[tank1949]

Motor size is 4.3L and fresh water only. I think any structural work is beyond what I want to tackle and would sooner scrap the boat, but everything seems fine structurally at the moment. It's definitely not perfect, but it is adequate for us for now.

I believe, but not 100% certain, that after 1995, boat manufatures discontinued using wood in transoms. So, please do web search to verify and help you decide on any future used boat purchasing decisions. Good luck!

 

[timharper89]

I believe, but not 100% certain, that after 1995, boat manufatures discontinued using wood in transoms. So, please do web search to verify and help you decide on any future used boat purchasing decisions. Good luck!

I do my best, but unfortunately it is sometimes difficult to find out exactly when things happened for each boat make and model. Lots of conflicting information out there, but I do my best to find things out

 

[Rick Stephens]

Motor size is 4.3L and fresh water only. I think any structural work is beyond what I want to tackle and would sooner scrap the boat, but everything seems fine structurally at the moment. It's definitely not perfect, but it is adequate for us for now.

I just read through your thread. Great job spelling out your thoughts and possible paths. Those posting some answers know what they are talking about and you got some great detailed answers.

One thing I would recommend is before you spend a penny, take a drill and do a couple test holes as low in the transom as you can, from the inside, as close to the keyhole as can be reached without going closer than an inch or so. Use tape wrapped around the drill bit to set hole depth to about and inch and see what condition the wood is that comes out of the holes. Those holes can then easily be filled with 3M 5200 from a small tube and you will know for sure how structurally sound your boat is.

If you are running a 19 inch now, I would try out a 17 inch prop. I run a 'cheapie' 4 blade Solas on my boat and it really helps it jump out of the water. I also run Smart Tabs which get the planning speed down even more. I'm not recommending those, to you, but mention it so you know there are many options to getting your boat to perform more on par with how it should. With the prop I run, if I am not paying attention, I can over-rev it a little. That said, and as achris mentioned earlier, you get a much more responsive boat and a very efficient cruise. This is especially important if you load up the boat with people and or pull tubes and boarders and other toys.

Rebuilding a motor is an exercise in being anal about details. Anyone can do it, but to do it right takes good advisers, the rights tools and a little modicum of experience wrenching.

 

[nola mike]

I read through that, but it seems mostly relevant if you are trying to change over internals between models. Am I wrong here? If I buy a long block, how much does it matter that the internals are different? I see the heads and intake might be different, but what else is relevant to swapping a long block? The cam bearing differences if I have to swap the cam?

Kind of. There are differences in the block that matter if you go newer. The peripherals don't always swap over, the newer blocks have different degrees of metric threads, the water pump might not fit, starter might not fit, etc. Newer blocks had serp belts instead of v-belts. That said, you'll probably have a much easier time getting a newer scrap truck 4.3 from a yard that has balance shaft, vortec heads, roller cam, etc. I pulled one with high miles from a blazer for $180 and transferred the components from an '89 marine engine. That would be the most cost effective route.

 

[timharper89]

I just read through your thread. Great job spelling out your thoughts and possible paths. Those posting some answers know what they are talking about and you got some great detailed answers.

I tend to overthink things. Sometimes it is helpful, most of the time it seems not so much

One thing I would recommend is before you spend a penny, take a drill and do a couple test holes as low in the transom as you can, from the inside, as close to the keyhole as can be reached without going closer than an inch or so. Use tape wrapped around the drill bit to set hole depth to about and inch and see what condition the wood is that comes out of the holes. Those holes can then easily be filled with 3M 5200 from a small tube and you will know for sure how structurally sound your boat is.

The idea scares me ignorance is bliss, right? I will need to get some 5200. I'm thinking I can probably skip winter maintenance on the motor, aside from draining the block of course. I guess I can grab a tube of 5200.

If you are running a 19 inch now, I would try out a 17 inch prop. I run a 'cheapie' 4 blade Solas on my boat and it really helps it jump out of the water. I also run Smart Tabs which get the planning speed down even more. I'm not recommending those, to you, but mention it so you know there are many options to getting your boat to perform more on par with how it should. With the prop I run, if I am not paying attention, I can over-rev it a little. That said, and as achris mentioned earlier, you get a much more responsive boat and a very efficient cruise. This is especially important if you load up the boat with people and or pull tubes and boarders and other toys.

I currently have bennett trim tabs and a 4 blade. I could try a 17 pitch. If I get a bit more power from the new motor through 4bbl and vortec, maybe I won't need a different prop.

Rebuilding a motor is an exercise in being anal about details. Anyone can do it, but to do it right takes good advisers, the rights tools and a little modicum of experience wrenching.

Sounds like repowering with a truck block would be more economical than rebuilding, depending on what accessories will need to be replaced and what fits on the new motor

 

[timharper89]

Kind of. There are differences in the block that matter if you go newer. The peripherals don't always swap over, the newer blocks have different degrees of metric threads, the water pump might not fit, starter might not fit, etc. Newer blocks had serp belts instead of v-belts. That said, you'll probably have a much easier time getting a newer scrap truck 4.3 from a yard that has balance shaft, vortec heads, roller cam, etc. I pulled one with high miles from a blazer for $180 and transferred the components from an '89 marine engine. That would be the most cost effective route.

One local pull apart has a few motors for $199 plus $75 core and $60 if I want a 90 day warranty. 2 full sized pickups and an s10. Is there a preference between vehicles out comes out of? Will the full sized trucks have a more appropriate cam?

 

[achris]

The '185' was the first iteration of the 4.3. But, it's still a 4.3 in essence, so we can work with that. Looks like it has a 2bbl 'Mercarb', and the old style solid mounts and no balance shaft.

Given that, 3 options.
1. Rebuild yourself, and all that involves. (Machine shops, lots of time in the garage, many trips to parts shops and a mostly open wallet). Budget, $3,000???
2. (and this is the one I'd probably look at) Get a long block with Vortec heads with a 4 bbl manifold and flywheel, and build it up as a 220hp 'late model'. You'll need an electric fuel pump and an Edelbrock 1409 carb to go with it, but the rest of the externals should just bolt on. If you need new exhaust manifolds, look very seriously at dry-joints. Budget for this, if you're doing most of the 'donkey work' yourself would be around $4,500 (not including exhaust manifolds and elbows).
3. Complete engine, ready to drop in. Budget $6,000

Chris.......

 

[achris]

This is a balance shaft...


The first generation of 4.3L engines didn't have them. As these are an even firing crank, 90° V6, they are inherently unbalanced. 60° would be balanced (think Merc V6 outboards). What was found was that under load at around 1700-2200 rpm there was a distinct vibration. In a car, it's barely noticable, but in a boat that's usually right on the engine speed to get the boat up onto the plane, and through solid mounts and a solid hull, oh yeah, you better believe it was noticed! Merc's first attempt to reduce that vibration was fluid mounts.

Big and squishy...

Around 1992 GM came up with there own solution, that balance shaft in the picture above. It runs at the camshaft speed (1/2 engine rpm) and in the opposite direction. It works rather well, but does cost a few horsepower. So Merc went back to solid mounts and have done all the way until the end of the 4.3 V6.

Chris.......

 

[achris]

One local pull apart has a few motors for $199 plus $75 core and $60 if I want a 90 day warranty. 2 full sized pickups and an s10. Is there a preference between vehicles out comes out of? Will the full sized trucks have a more appropriate cam?

Truck and pickup cams are usually the same. Not sure what an 'S10' is... (I'm not in the US and we don't have any US built cars here, apart from Jeeps )

This may answer your question -> General Motors 90° V6 engine

Chris......