1987 Merc 4.3 Rebuild or replace?

[achris]

Very brief, very quick starting point for '4.3L 101' (I'm sure plenty of posters are going to jump right in and say 'you missed.........' Yes, BRIEF!)

Generation 1 - No balance shaft. 1985 to 1992
Generation II - Balance shaft. 1992 to 1996
Generation + - Balance shaft, composite timing cover, Vortec heads and Thunderbolt V. 1996 to end of line.

Now, there are many smaller variations within each generation, and even the 'same' engine built in the 2 different plants (Tonawanda & Romulus) have differences.

For the best write-up I've seen detailing those variations, click here (WARNING, there are 13 pages!) -> Chevy V6

Chris......

 

[timharper89]

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???

That much to rebuild myself? Ouch. I can buy a long block for $2k. I was assuming it would be cheaper to do it myself. I wouldn't be doing it simply for the great learning experience. Budget is the largest factor here.

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).

This is buying a rebuilt long block? I can get one for $2000 delivered. Is there really $2500 more I need to invest before exhaust manifolds? Seems like I could buy all my bolt on accessories and still not spend that much. I must be more ignorant than I thought :/ Maybe things are more expensive where you live?

3. Complete engine, ready to drop in. Budget $6,000

Definitely not an option. Honestly, all these costs (except the drop in motor) are quite a bit above what I was thinking it would cost me. There is no way my wife is going to let me drop $4500 into this boat. Not sure I even want to either. At that point, we're digging deeper into our boat fund anyway and might as well just give the boat away.

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 )

an s10 is a small, light duty pickup truck. (picture). I wasn't sure if being lighter duty it would have differences that would make it a little less suitable for marine application.

I was starting to lean toward a truck donor motor for a low cost option, but you seem to have removed that as an option. Was that on purpose for some reason based on my motor? Maybe the prices are lower here in the US *fingers crossed*. There is also a boat parts/salvage yard that will sell me a used long block for $650. Outside the cost of the motor, I would need a new vortec intake, manifold gaskets, carburetor....What else? I already have an electric fuel pump due to a fun project when I found out that one of the POs had to replace the block and replaced with one without a mechanical fuel pump hole, then proceeded to put an electric pump on that had too much pressure and was flooding the carb and didn't install an oil pressure cutoff switch for the pump....So I have a new solid state electric fuel pump that is only a few years old.

 

[timharper89]

If you need new exhaust manifolds, look very seriously at dry-joints.

I would be replacing my manifolds. They froze and were repaired by the previous owners. I wouldn't want to put them back on. Is there a large advantage of dry joints in freshwater? I was under the understanding that manifolds can last decades in freshwater

 

[Rick Stephens]

If you could find a Pre-Vortec longblock used that would be one thing, cost wise. (note, I did that - I went with a pre-balance shaft block, Vortec heads, Performa intake, Edelbrock 1409 carb. I reused, and am still running the original exhaust manis as they are still clean as a whistle from the type water here in Idaho. I reused all bolt on accessories)

If you go a newer Vortec block things start getting interesting $$ wise. Still need intake, carburetor and if yours are bad, exhaust, but you will also need water pump (automotive ones rust out in months, not years and Vortec pumps are different), serp pulleys and or new bolt on accessories (power steering pump, alternator, idlers), flywheel, timing cover. Also make sure your fuel pump is marine rated.

Can be done on a budget? Well, sorta. Boats don't really do well towards budgets, little crap and bigger crap keeps on going.

 

[Lou C]

S10 was the mid sized Chevy and GMC pick ups that used the 4.3 extensively.

 

[matt167]

The Full size Chevy trucks used the 4.3L as well. Many 2wd work trucks and even 4wd trucks had them.. To get something that is as near bolt in and go as you can, find one in a similar year to your boat and use it. Just swap core plugs and head gaskets for marine versions. Will cost you $100 extra + your time. A 4.3L in the automotive world is near worthless and can set you back as little as $100-200 for something that will run ( U pull junkyard ). Keep in mind that S truck cams I am pretty sure are slightly different than the full size cams. Both are mild enough to work in a marine engine

 

[timharper89]

If you could find a Pre-Vortec longblock used that would be one thing, cost wise. (note, I did that - I went with a pre-balance shaft block, Vortec heads, Performa intake, Edelbrock 1409 carb. I reused, and am still running the original exhaust manis as they are still clean as a whistle from the type water here in Idaho. I reused all bolt on accessories)

So you went with an older motor and converted it to a vortec? I honestly still have the option to keep my current non vortec intake and 2bbl carb and save that much money. The carb is around $500 and the intake is another $400 Heads are another few hundred. That saves me over a grand at the cost of performance. If a 17 pitch prop doesn't seem to make us happy, I would maybe consider the extra cost there, but 90% of the time, we are out with a manageable load and don't have a problem with the lack of power.

If you go a newer Vortec block things start getting interesting $$ wise. Still need intake, carburetor and if yours are bad, exhaust, but you will also need water pump (automotive ones rust out in months, not years and Vortec pumps are different), serp pulleys and or new bolt on accessories (power steering pump, alternator, idlers), flywheel, timing cover. Also make sure your fuel pump is marine rated.

This would mean I can not use my current intake and carb, correct? I COULD just use my heads, but is there any reason to go that route if I decided not to do the vortec and 4bbl? Unless I wanted the vortec heads to come with the motor to save myself from having to buy those if I did end up deciding to convert to vortec in the future, but would I save money if I had to buy a new water pump and and other accessories? Ugh I wish I had a crystal ball...

Can be done on a budget? Well, sorta. Boats don't really do well towards budgets, little crap and bigger crap keeps on going.

Budget is limited. Again, this is kind of a (expensive) bandaid to keep us on the water while we patiently look for our next boat, so we don't want to invest much into it. We definitely aren't going to see any ROI with any of this. If I can add some performance for a little extra, I'll consider it, but it appears I'm looking at nearly $1000 solely for extra power, correct? If we were going to use this boat for the next 8-10 years, I would be ok with that, but maybe 2 or 3 years tops before we move on I think. I think we will be much happier with a 23-24 foot cuddy, so I will probably try to make it work without the extras unless I can find them used for a good price.

 

[nola mike]

You can pull a block yourself and you can get it done for well <$2k.
If you want to do vortec:
1. If you can find a stick it will save you from swapping the flywheel
2. You'll need new: water pump (<$100), starter (<100) (or you can drill out the holes on your original to fit M10 bolts--a new pmgr starter is pretty cheap though). Other accessories will bolt on.
3. Carb. Used 1409 ~200
4. Intake: $200
5. Exhaust manis: I didn't go dry joint because my elbows were fine. ~$300
6. Misc items: carb throttle bracket, gaskets, a bunch of metric hardware...all I can think of ATM.
The newer blocks I'm betting all come with composite headgaskets and brass core plugs (my '01 did). Plugs are easy to check with a magnet. HG no easy way, up to you if you'd want to roll the dice, esp in fresh water.

Here are the gory details of my swap:

Nola Mike's 3.7/470 --> 4.3L swap thread

I'm sure that this will be a saga, so starting a new thread. Just picked up an '89 Glastron donor with a 4.3. I'm planning on refurbing the engine and adding a 4bbl carb and vortec heads. I'm going to start on the engine in a bit, and then swap it in the fall after the season. 1st question...

forums.iboats.com

 

[achris]

If you want 'as cheap as possible', then rebuild what you have, use the same 2 bbl manifold and carb, get HGE exhaust manifolds and elbows. But the one place I would not 'save money' is the prop. If you are wanting to improve the feel of the boat, drop down a prop size, without question. If you're currently running a 17", DEFINITELY drop to a 15". It's actually quite possible it was overloading the engine (with a prop that's too big) that killed the engine in the first place.

Chris.......

 

[Rick Stephens]

By your very clear definition you will need to find a pre-vortec motor and swap over your parts and pieces. As soon as you go to a '96 and newer Gen+ block with Vortec you add in at least $1500 to $2k in parts swaps. IMHO, $1000 is a pipe dream.

Next thing is balance shaft. That got added in '92. That changes water pump and front timing cover. The '92 through '95 motors are morphodite bastards and can be hard to find timing covers, gasket sets for.

 

[Rick Stephens]

Here are the gory details of my swap:

You did have a few days of bloody gore.

Does make for some unique knowledge about these motors though.

 

[Rick Stephens]

If you want 'as cheap as possible', then rebuild what you have, use the same 2 bbl manifold and carb, get HGE exhaust manifolds and elbows. But the one place I would not 'save money' is the prop. If you are wanting to improve the feel of the boat, drop down a prop size, without question. If you're currently running a 17", DEFINITELY drop to a 15". It's actually quite possible it was overloading the engine (with a prop that's too big) that killed the engine in the first place.

Chris.......

I don't think that a rebuilding option comes close to a used pull in lower cost - unless you have to rebuild the pull, of course.

 

[Lou C]

If you want 'as cheap as possible', then rebuild what you have, use the same 2 bbl manifold and carb, get HGE exhaust manifolds and elbows. But the one place I would not 'save money' is the prop. If you are wanting to improve the feel of the boat, drop down a prop size, without question. If you're currently running a 17", DEFINITELY drop to a 15". It's actually quite possible it was overloading the engine (with a prop that's too big) that killed the engine in the first place.

Chris.......

I use a 15.5x15 prop on my 4.3 OMC Cobra which has a 1.60:1 drive ratio in a boat (200 Horizon) that’s a bit longer and heavier than the 195 the OP has and it performs quite well. Will definitely pull 4900-5,000 WOT.
when I got the boat years ago it had the wrong prop for sure (14.5x19) I went to a 15x17 (better not perfect) and settled on the 15.5x15.

 

[achris]

I use a 15.5x15 prop on my 4.3 OMC Cobra which has a 1.60:1 drive ratio in a boat (200 Horizon) that’s a bit longer and heavier than the 195 the OP has and it performs quite well. Will definitely pull 4900-5,000 WOT.
when I got the boat years ago it had the wrong prop for sure (14.5x19) I went to a 15x17 (better not perfect) and settled on the 15.5x15.

I think people seriously underestimate just how much significance propellers have on a boat's handling and performance.

When I first bought my boat it had a '165' inline 6 in it, and 17" prop. It pulled 3950rpm (in spec) but just felt 'underdone'... I changed to a 15" (same style, both 3 blade ali) and it was like a different boat!
Recently I changed from a 3 blade SS 17" to a 4 blade SS 17" and again, the difference is night and day. When I first put the first V6 in (1994), the dealer talked me into a 3 blade Mirage (HUGH mistake!). After the first trip out I almost put the boat on the market and sold it, it was that bad! I considered buying back the 165 and putting it back in too. Eventually I just put a 21" 3 blade ali on, and it was back to the nice boat I remembered. So yeah, props maketh the boat!

Chris.........

 

[nola mike]

By your very clear definition you will need to find a pre-vortec motor and swap over your parts and pieces. As soon as you go to a '96 and newer Gen+ block with Vortec you add in at least $1500 to $2k in parts swaps. IMHO, $1000 is a pipe dream.

The intake, carb, throttle bracket, water pump, bolts, and +/- starter are the only add ons needed for the vortec. Well under $1k. Can you get a 2bbl vortec intake?

Next thing is balance shaft. That got added in '92. That changes water pump and front timing cover. The '92 through '95 motors are morphodite bastards and can be hard to find timing covers, gasket sets for.

Yeah, I'd avoid the non-vortec balance shafts for that reason. When I was looking at the yards, nearly everything was newer/vortec.

 

[timharper89]

If you want 'as cheap as possible', then rebuild what you have, use the same 2 bbl manifold and carb, get HGE exhaust manifolds and elbows. But the one place I would not 'save money' is the prop. If you are wanting to improve the feel of the boat, drop down a prop size, without question. If you're currently running a 17", DEFINITELY drop to a 15". It's actually quite possible it was overloading the engine (with a prop that's too big) that killed the engine in the first place.

I did a lot of reading when I bought my prop. It was DEFINITELY over propped when I bought it. (23 pitch) Most of the time, it doesn't feel bad to drive. It's just on occasions we have family out for a ride that it really struggles. Might have been the nail in the coffin trying to ski and whatnot though. I will try to prop down to 17 and see how that feels after I get the motor sorted. I have learned a TON by buying this boat. It seems everything I do I have to learn an entirely new language. Still have it seems infinitely more to learn though.

 

[timharper89]

I use a 15.5x15 prop on my 4.3 OMC Cobra which has a 1.60:1 drive ratio in a boat (200 Horizon) that’s a bit longer and heavier than the 195 the OP has and it performs quite well. Will definitely pull 4900-5,000 WOT.
when I got the boat years ago it had the wrong prop for sure (14.5x19) I went to a 15x17 (better not perfect) and settled on the 15.5x15.

Isn't 5000 under propped? 4400-4800 is "spec". You just prefer the performance that way? I already only get 35 mph (cruise at about 25 mph at 3500 rpm. Won't stay on plane any lower than that) on the best of days with 19p and I think 4600 rpm. What was your top speed loss going from 19 to 15?

 

[timharper89]

You can pull a block yourself and you can get it done for well <$2k.

Under 2k sounds good. That's about what I was hoping.

If you want to do vortec:
1. If you can find a stick it will save you from swapping the flywheel
2. You'll need new: water pump (<$100), starter (<100) (or you can drill out the holes on your original to fit M10 bolts--a new pmgr starter is pretty cheap though). Other accessories will bolt on.
3. Carb. Used 1409 ~200
4. Intake: $200
5. Exhaust manis: I didn't go dry joint because my elbows were fine. ~$300
6. Misc items: carb throttle bracket, gaskets, a bunch of metric hardware...all I can think of ATM.

Is this what you did with yours? Where did you source the used carb and intake? Looking on ebay, I don't see anything, and new carbs are closer to $500.

The newer blocks I'm betting all come with composite headgaskets and brass core plugs (my '01 did). Plugs are easy to check with a magnet. HG no easy way, up to you if you'd want to roll the dice, esp in fresh water.

Here are the gory details of my swap:

Nola Mike's 3.7/470 --> 4.3L swap thread

I'm sure that this will be a saga, so starting a new thread. Just picked up an '89 Glastron donor with a 4.3. I'm planning on refurbing the engine and adding a 4bbl carb and vortec heads. I'm going to start on the engine in a bit, and then swap it in the fall after the season. 1st question...

forums.iboats.com

I will read over this. Sounds like you had fun with that one.

 

[nola mike]

Under 2k sounds good. That's about what I was hoping.

Is this what you did with yours? Where did you source the used carb and intake? Looking on ebay, I don't see anything, and new carbs are closer to $500.

I will read over this. Sounds like you had fun with that one.

Ebay for the carb. Intake was new.

 

[achris]

Isn't 5000 under propped? 4400-4800 is "spec".

Yes and no. 4400-4800 is the spec, but as most of us rarely run at WOT all day, 5000 isn't going to hurt anything. And since you want to ski, you are most definitely OVER-propped at 4400 (despite it being 'right in the middle')... The recommendation for skiing is to find the size of the 'right' prop (at or near the top end of the range), then drop down another 2"..

You just prefer the performance that way?

You will only find a benefit in performance. Better acceleration, better sea holding, better 'driveability'.

I already only get 35 mph (cruise at about 25 mph at 3500 rpm. Won't stay on plane any lower than that) on the best of days with 19p and I think 4600 rpm.

That may be down to a dying engine. Or it could be just the hull design. It is only 185hp. My top speed (similar boats) with the 165 was 30 knots, the 4.3LX (205hp) was 38 knots, and the 4.3MPI (220hp) is around 42 knots. If you are having trouble staying on the plane, move the ballast (passengers) forward. I know they love congregating at the back of the boat, which forces the stern down. Tell them to move forward, or get off the boat!

What was your top speed loss going from 19 to 15?

You might lose a knot or 2 but since, as I said earlier, we don't stay at WOT all day, it's a very small price to pay.

Chris.....