Starting to look for a 4.3L, what do I need?

[nola mike]

Have been idly looking for a 4.3L to eventually replace my 470, see this link if interested. I'm trying to figure out what exactly I need. Looking for a junk hull is proving to be a bit elusive.
1. So what years are acceptable, are there any that don't work? I want to go vortec heads and 4 bbl carb, but for example what if I find a 2bbl pre-'96? Would it be worth it to buy some heads from a junker and source a carb? What other parts (intakes, etc) would I have to find?
2. Buying an engine in a (presumably) non-running boat--any way to check for a cracked block easily? What else do I look for?
3. What should I have done to the block/heads?
4. What's reasonable to pay for all this?

 

[nola mike]

OK, so just came across an '88 with outdrive for $300. Says it doesn't turn over, doesn't know anything else about it. 2bbl. He's got a hoist and I can just take what I want from the boat and leave the hull. I don't have room to keep a spare boat without getting divorced, so this is pretty attractive...

 

[Lou C]

If it were me I'd probably run the 470 till something made me think it was really time to up grade. Then if you have to justify spending money and making a mess in the garage to your better half you'll have a much easier time. They tend to have trouble with taking an engine out that is running just fine and spending money & making a big mess and spending untold hrs working on it just to have 'more power'. So when my old 4.3 blew both head gaskets last year I had a plan in mind...one...I wanted to try to do a top end overhaul myself, the other, if this was not successful, then my better half would understand that I tried everything short of getting a new long block. See if I was doing this, I would not at all have the patience to look at used motors, junkyard motors, etc. If I am going to the trouble of pulling the motor, its gonna be new. The only exception I'd make to that, is if my bottom end craps out, then with a trusted machine shop, I'd get a reman short block and put my reman heads on that. But anything else is too much of a long shot for my risk tolerance....

​BTW in a boat your size a 4.3 4bbl will be great. More than enough power and it will fit with room to spare (ie you can easily add a heat exchanger if you want closed cooling). The non balance shaft ones do run rougher, but that is mostly noticeable at low revs like under 1500 or so, not at higher speeds. It is easier to find intake manifolds and heads for the newer style Vortec engines and they do add about 20 hp.

​Looking at engines, stuff that doesn't run, if you can't run it to check the compression at least, I'd say pass on that. Why haul home someone else's junk? Unless you really want to do a full rebuild yourself, which of course is a great learning experience, but not everyone wants that.

​BTW I am running a 30 year old OMC Cobra system, I have been looking at both VP or Merc conversions but as long as it works, I'm keeping the Cobra. When I have to replace the drive, or the transom mount gets too corroded due to its life in the salt pond, then its time. For now, why change what still works?

 

[Scott Danforth]

Here is some reading http://forums.iboats.com/forum/engi...history-of-the-4-3-liter-with-casting-numbers

skip the junkyard heads. new vortec heads are about $500 a pair. a used vortec intake is $50 for cast iron or $75 for aluminum on ebay.

skip the '88 you found. doesnt turn over is a giant red flag and siren saying "im a scrap motor all busted up). unless you get it for free for the accessory brackets and the oil pan, its not worth it. if you buy a used motor, buy a running motor.
you need to do nothing to the heads unless you want to de-flash the combustion chamber and smooth up the exhaust ports.

buy new manifolds and risers. I also recommend buying a new water pump (circulating pump) and new starter and alternator

fYI - Running motors from S-10 trucks are about $200 sometimes you get the whole truck for that price and you sell the parts and come out money ahead.

find a 92 or later balance shaft motor if you want a smooth runner. vortec heads came in 96.

There was a 2002 S-10 in the local craigslist a week ago. hit hard, motor still ran good, 65000 miles, $100

 

[nola mike]

Scott Danforth , thanks for the link. I'm sure you'll be happy to get another 470 off the water. I'm in no hurry to do this. Eventually my 470 will go, and it would be nice to just drop in a new engine on my timeline. Can't justify spending more than $2k on this boat; just put nearly that much into redoing the floor/interior. The $300 boat I figured would have all the little bits and accessories that I need. If the outdrive is good, there's my money right there. Then I'd probably buy a junkyard longblock and swap everything over--I'd feel more comfortable with a truck engine with 100k miles on it v. a marine engine anyways. What I don't want is to get the auto engine for cheap, and then spend a bazillion dollars for little parts to make it work right in the boat.

 

[Lou C]

The one part that is important and can be a little hard to find for the pre-vortecs is a marine intake. The trucks that used these engines mostly came with throttle body injection but the marine intakes for the 2bbl and 4bbl carbs are different. They are not that easy to find for the pre vortec but more plentiful for sure for the vortec engines. I just picked up a very good condition one for a spare off of ebay, fresh water used. The other stuff is the p/s pump and mount, alt bracket, and mount, etc. Since you're doing a Merc here the parts are very plentiful and cheap.

 

[Scott Danforth]

Scott Danforth , thanks for the link. I'm sure you'll be happy to get another 470 off the water. I'm in no hurry to do this. Eventually my 470 will go, and it would be nice to just drop in a new engine on my timeline. Can't justify spending more than $2k on this boat; just put nearly that much into redoing the floor/interior. The $300 boat I figured would have all the little bits and accessories that I need. If the outdrive is good, there's my money right there. Then I'd probably buy a junkyard longblock and swap everything over--I'd feel more comfortable with a truck engine with 100k miles on it v. a marine engine anyways. What I don't want is to get the auto engine for cheap, and then spend a bazillion dollars for little parts to make it work right in the boat.

the 470 doesnt bother me. they simply disappoint me from a design standpoint. as I stated, would make a good 4-banger hot-rod motor for a model a or a model t. however does require fixing a bunch of its inheirant design flaws by switching to an aluminum head, making a block girdle for the cylinder bores, etc.

I fully understand the desire to pick up a non-working motor and a running long block. many of the things that you may think have value, will need to be replaced (manifolds, rotating electrics, etc.) so you are looking at accessory brackets, controls and any drive stuff. however you need to formulate a plan and then look for the deals

specifically, pick the motor architecture that you intend to use:
2-piece or 1 piece RMS
with or without balance shaft
mechanical or electric fuel pump
vortec or non-vortec heads
aluminum or cast iron intake

then gather parts specific to that motor

I would target a post 92 setup for the balance shaft because I can always buy vortec heads and intake and I would want a mechanical fuel pump.

 

[nola mike]

Yeah Scott, I think that's a big issue, knowing which parts I need and which can't be interchanged. Iirc all the newer engines are 1 piece rms, although I don't know what that changes (starter? Flywheel? Coupler?) downstream. Don't know that I care a ton air balance shaft; I wouldn't mind trading a smooth idle for 15 hp. If I buy a marine parts engine I'd get a fuel pump (extra expense otherwise), worst case I get an aftermarket electric. Definitely vortec heads and a 4bbl carb. Parts that I can see needing, a junk engine may help:
1. Ignition. Could get aftermarket, adds $$
2. Accessory brackets. Don't know how easy these would be to get
3. Intakes. Guessing I'd need something specific for a vortec/4bbl? Probably eBay unless I find the exact engine. Don't know about al v cast
4. Exhaust. This I bet can get pricey. I've read some about the different manifold setups. I don't think these are engine-specific? In addition to manifolds and risers, I'd also need y pipe, bellows, what else?
5. Would like to keep my alpha 1 gen 1. Are there any differences from the engine side that would make an older engine better for this? Any incompatibilities?
6. That $300 boat is an 88, so would have a 1.65:1 drive. I think I'd need one of those since I'm already running a 23p prop on a 1.84. The 1.65 isn't as plentiful around here. Don't know if I'd be able to prop a 1.5 correctly. Guessing i could

so what wouldn't make that $300 motor worth getting? Outdrive, starter, brackets, exhaust bits (now I'm remembering I'd need t stat housing, plumbing, wiring harness?) Seems are worth that easy.

 

[Lou C]

It would make even more sense if the engine ran, and you could at least do a comp test on it, or pull off one of the valve covers to see if it was all sludged up or had water in the oil (looks like mayo under the valve cover). So maybe keep looking for that rotted boat with a still running engine and drive. Then you'd hit the jackpot as far as getting all the little bits for a bargain price. The '88 is pre vortec, no balance shaft but likely has a roller cam. If the guy who owns it will let you try to get it running (who knows could be somethin' simple he could not figure out) it might be worth a 2nd look. Are these fresh water or brackish/salt? Because if fresh, fine but if brackish/salt, the manifolds & risers could be all clogged with rust, the intake could be rotted, as could be the heads, etc. If you find a running fresh water boat, V6/Alpha, in good shape mechanically, do not even worry if its pre-vortec, the power difference is not huge, you can always add a 4bbl if its a 2bbl, etc.

 

[Bondo]

Have been idly looking for a 4.3L to eventually replace my 470,

Ayuh,.... Newer is Better, especially when talkin' the 4.3l motors,.... but any of 'em are miles ahead of what it's replacin',.....

A Non-runnin' motor is a Rebuildable Core motor, 'n must be priced as such,...
Plan on the price of a Long Block crate motor replacement,....

Ya might get Lucky, 'n a battery, 'n a splash of gas get's it goin', but don't bank on that, Regardless what the fella sellin' it says,....
Plan on a long block replacement,....

Ya also have to be careful not to buy a boat with a cracked block,.....
If a seller offers to light it up for a few seconds without water,.... walk away,.....

 

[nola mike]

Yeah Bondo , I'm assuming the motor on this one is trashed, but still worth the $300 for the other components. If I get a marine 4.3, I plan on vortec heads, and at the very least a refresh v rebuild. I'm thinking a lowish mile truck engine would be cheaper, easier to find, no worry about cracked block, and probably in better shape with 100k miles than any 25 year old marine version (esp salt water). Even if I can get it going, one of the reasons to do the swap is to put something fresh in there that I don't have to worry about.

 

[nola mike]

Still thinking I may buy that $300 junk engine and then sourcing a 96+ truck engine and just freshen it up before install. My local pull a part has a total of 10 astro/s-10 post-'96 engines currently. Mileage/condition unknown, for $340 +$30 core, +$127 for them to pull it. A carfax report or something could probably tell me the approx mileage, and looking at the truck will tell me the likely cause of death. Then I take it to the machine shop, and what? Cylinder hone/rings, oil pump? Valves? HG, core plugs. If I went the latter route, here's what I'm looking at for a price breakdown:
1. $300 junker. This gets me the outdrive/transom assembly, accessories, ignition, brackets, engine harness, 2bbl carb and probably other sellable parts (inc a $30 core). Don't know if I could use the y-pipe, exhaust bits? I'm going to see if the guy will pull everything for me. If so, I might kick him another $100. Seems like a no brainer.
2. Engine. $470.
3. Machine work. $500? Total WAG, someone set me straight on what I'll need and what it would cost.
4. Extra stuff: Here's where it could start to bite me, right?
a. I'll need a carb ($200 used)
b. intake manifold? (can i use what's on the old boat with an adapter or something for the 4bbl? otherwise I'll assume I can find a used one for $200).
c. Exhaust manifolds/risers (not sure what exactly I need here, but I'm finding $800 for manifolds and risers?! Is this correct? And this is maintenance? Someone can hopefully set me straight)
d. Coupler. Can/should I reuse the old one? $300, yikes.
e. Fuel pump $75

Which brings me up to ~$1600, not including exhaust bits, which would be a killer. I'll assume that best I can do is 1/2 that, so I'm in it $2k.

The good news, sellable parts!
1. Old carb from junker, old carb from my boat $250
2. exhaust manifolds from the 470: $200
3. Exhaust reservoir $50
4. Heat exchanger: $125
5. Alt conversion kit: $100
6. Block $150
7. I actually have a complete extra 470 engine with all the trimmins', so I'll be able to part that one out as well, but I won't count that for these calculations.

$900 so far from that, + a lot of other misc 470 bits would probably get me to $1k easy. So not bad. My goal for the complete swap would be <$2k, so after parting I should still be well under that. What other parts am I forgetting? How's this plan looking?

Rick Stephens , would appreciate your input.

 

[nola mike]

So...My buddy has a '93 (I think) formula with a 4bbl V6. His wife hit something about a year or 2, cracking the lower unit and blowing out the coupler. He has just managed to get it fixed, but when the shop was about to put it in, noticed that he had rotten stringers. So now I may be able to buy the boat from him. I'll see if I can get a serial #, but I assume this should be a balance shaft non vortec 1 pc RMS, correct? If so, what would I need to upgrade this to vortec heads (aside from the heads). What would be a fair price for this?

 

[Scott06]

That formula sounds like a better deal , I believe you are correct that it will be a balance shaft non vortec, 205 hp with a webber carb. total upgrade and great move if it works out between you and your friend. Vortec head plus intake would be required to upgrade but probably only net 20 hp. Carb would work but probably need re jetting/plug reading. IMHO, you're already getting 30 more hp, so I'd leave well enough alone if the engine is still in good shape.

On the other one, yeah you can piece it together from a potentially locked up mercruiser and junkyard engine, but it's still a pile of used parts. I'd did a repower two years ago, my father and I bought a low hour boat with a cracked block. My dad, who still talks to me like I'm 12 at times, was adamant about getting a new base engine, no used, no rebuilt etc. bottom line I spent $2k more than I planned but in the end when we put it in, it started right up and I have had two trouble free summers out of it, and expect the same this year. So in the end the money didn't kill me, just having the time out on the water with our daughters and their friends, plus a happy admiral was money well spent.

 

[nola mike]

Hmm. Either way it's used parts. Local pick 'n pull has heads for $30 each (they're cast iron, right?). Bet I can find a pair. If I'm going to all this trouble, might as well go vortec. So questions would be:
1. If I pick up this engine and want to go vortec, I'd just need a new intake + heads?
2. Was reading a bit about the v8's, and it doesn't look like they're all mix and match. But for the V6's, it seems like I can use any '96+ vortec head?
3. Lastly, what vehicles are these in? I'm seeing Blazer/Jimmy, Astro/Safari vans, Oldsmobile bravada, s-10/sonoma, silverado/sierra. Anything else?

 

[Bondo]

I'd just need a new intake + heads?
But for the V6's, it seems like I can use any '96+ vortec head?

Ayuh,.... Correct on both counts,....

 

[Watermann]

Not sure if I missed it being said in the thread but to go from an inline to a V6 you will also need to build new motor mounts.

I did a V6 conversion from an old 120 and I have the complete measurement schematic for the 4.3L MC motors in PDF that can help you out so if interested send me a PM with your email addy.

 

[nola mike]

Watermann , thanks for that, will PM. I'm actually going from a 4 banger to the v6. All the floor resto made me brave enough to try to glass some mounts in myself when the time comes.

 

[nola mike]

Just came across this on CL. Can anyone tell the vintage based on the pics? Price is right, though I might see if he'd be willing to pull the drivetrain for me if I paid him. I don't have the time or space to deal with a junk hull. Assuming the block is trash--anything else that would be useable for me? Looks like a gen 1 drive, which is probably worth the price of admission...
Also looks like a 2bbl carb?
Actually, maybe he'd let me strip the parts I need--that could be worth my time. Controls, drive, brackets, ignition, starter, alt. Could I use the exhaust mani and risers with vortec heads? I'm still looking for a definitive list of needed parts, which are acceptable used, and which I need new. Can someone help out with this? I listed a few things earlier, but I'm thinking:
1. Carb. Used fine, but most of the junkers I've seen have 2bbl.
2. Intake. Will need new or used specifically for 4bbl/marine/vortec, right? Again, tough to find a package with this already there.
3. Exhaust mani/risers. Are these common to the vortecs/pre vortecs? Prices look like $800? Is that right?
4. Coupler. Would I want to reuse this, or better off new? Expensive, but pulling the engine/getting stranded doesn't excite me.
5. Alt/starter/Ignition. I'm OK going used with this stuff, and vintage doesn't matter, right?
6. Outdrive. Would be nice to get a 1.65 in case I can't prop my 1.84.
7. Y-pipe. Crap, forgot about this. Definitely a good used part candidate, will have to pull the engine to get it out.
8. Oil dipstick tube.
9. Water pump?
10. Any wiring or electrics, or can I reuse mine? Same wiring harness, right?

Whoops, forgot the link

 

[Rick Stephens]

When I bought a crapper hull I used all the power train, literally everything. I pulled all the 4 banger older stuff and sold it bit by bit. I also swapped the steering gear, cable and all. The crapper boat had a gear box while the rack and pinion one on my boat was a bit loosie.

I hauled the junk hull to the dump, tied the stern a D8 dozer and drove off.

I sold EVERYTHING. It paid for my entire swap from a 4 banger to the 6 including a partial rebuild of the new motor, resealing and painting the new (to me) outdrive, and RRing my transom and adding V motor mounts.

I sold:

Trailer
Full dressed running motor
hydraulic pump
outdrive
entire transom assembly
seat cushions and seats
windshield


I kept the electrical harness including the instrument panel. That let me plug it into a motor sitting on blocks and could key start, watch oil pressure and temps come up, see tach readings, and turn it off, all from the panel.

It would surprise me if you found a 1:1.65 with a 4.3. I've never actually seen one, although my understanding is they shipped on the injected motors.