1989 Lund Tyee w cracked 4.3. What yrs 4.3 will fit?

[bigtoyz]

I bought a very nice 1989 Lund Tyee but it has a cracked block (was completely rebuilt rebuilt 2 yrs ago). Ive read that GM pickups (S10, 1500's) 4.3 will install, have a little more vibration due to the absence of the cam balance shaft, and dont like to rev as high as long. Mine is not a Vortec, it has the older square valve covers. Are there any breakdowns of yrs that will work and yrs that wont? WIll the Vortec work with my intake,distributor, carb, exhaust, ect? I have access to a low mile 2004 GM motor but unsure if I can drop the distributor and intake on that block or if heads have to be changed out, ect. Any suggestion or known dont does?
Thanks for any info.

 

[Rick Stephens]

All of em will work.... some of them will require some different parts. A low mile 2004 would be a nice choice. You will gain Vortec heads, you will lose the ability to use your old non-Vortec intake manifold. Also the newer Vortec's will have serpentine belts, which means all the stuff hanging off the front has to either be re-shived or replaced with newer parts. So that's the interesting part. The fun part is some extra horsies under the doghouse. If you get a Vortec motor, the easy part is changing out the intake. Those pulleys are the hard part. Everything else pretty much fits. Oh, there is no mechanical fuel pump after something like 1995 blocks. So you will have to purchase and wire up an electric fuel pump.

 

[porscheguy]

Early 4.3s (yours included) should have been installed with hydraulic motor mounts that dampen vibrations that result from no balance shaft. The cover on your flame arrestot may even mention liquid filled engine mounts. Any 4.3 will fit. The newer, the more powerful. But as Rick mentioned, finding the accessories for a serpentine belt can be a pain. My boat is a ‘90 model that had the non balance shaft 4.3 and liquid mounts. I replaced it with an ‘01/‘02 4.3. I bought a low hour, excellent condition bobtail engine assembly. The only parts I reused from the old engine were the legs on the block that attach to the motor mounts because I was too lazy to drill new holes for the solid mounts. Overall, the install was plug and play simple.

 

[Scott Danforth]

To make your life easy. Stick with 88-91 unless you replace complete motor including accessories

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

 

[bigtoyz]

Thank you very much for the info. If I go with the '04 out of the pickup with accessories and the serpentine belt, eliminate the AC pump, shouldnt the alt and PS be adaptable? And then I would need to find a mercruiser vortec intake for the carb? Would the same exhaust manifolds work? And would a '04 still be a distributor HEI unit? My engine mounts are solid metal and the boat mount is rubber. I am guessing the liquid mounts would be available at the marine store.

 

[bigtoyz]

New results this morning. I bought it understanding they left water in it and ASSUMED the block was cracked, mechanic discouraged them from wasting money testing. I found one exhaust manifold cracked and a soft plug on each side pushed out. Ive always understood the soft plugs were the weak spots to prevent cracking the block so I spent an hr. installing rubber soft plugs so I could prove it to myself. I ran it for 45 minutes/1500RPM in the water last night, oil pressure, water temp stayed good, no noises or????, it actually ran very good. I let it sit overnight so water could separate from the oil, slowly pulled the oil plug and nothing but oil came out. Is there a better was to test for a cracked block on these motors? Ive actually had 4 of these motors, almost new, cracked across the lifter area from freezing ( a marine shop donated them to my HS auto program) and thats what I expected but really expected water in the oil pan. Can it be cracked and not leak? What should I do next?

 

[wahlejim]

Compression test would be my next step

 

[bigtoyz]

I will try that tonight. I will say it ran very smooth and did not seem to miss at all but I will try. Anything else? I did drain about 1/2 quart out and it looks like very good oil yet. I have it in a jar to see if anything settles out yet but I have seen no water.

 

[TyeeMan]

If the engine works out you will have yourself one fine boat (reference my username :glee: ).

My last Tyee (1995) had a 4.3L 4bbl with a Volvo drive, that thing was pretty quick.

My current Tyee Magnum came to me with a Mercury Remanufacturing rebuilt 5.7L, , actually 5.8L cuz they punche it .040" over. This thing is a rocket!

Good luck!

 

[Scott06]

What you identified from the donated motors (cracks across lifter valley below heads) is typical place where these blocks crack. It is possible that the core plugs were pushed out and the block didn't crack but that would be lucky. I have seen similar events in other peoples boats (core plug or cracked manifolds) take a couple of good hard runs out on the water before the crack opens up and contaminates the oil. Couple of options-

I would run it out on the water at speed get it good and hot under load and watch the oil on the dipstick. If it gets milky or level rises then you have water coming in. You will see evidence of this before the oil pan gets completely full and it comes out the rocker covers.

You can also pressure test the cooling system by plugging off the hoses and pressurizing the system with air at 15 psi if it holds you are ok, if it leaks listen in the oil fill cap for air. If it comes out the oil fill you have a crack somewhere-block, heads or intake water crossover.

You could also remove the intake and look for cracks but wouldn't be my first pick if its running and oil is clean.

If it were mine I'd run it close to the dock (or bring a friend w second boat to tow home if needed) and watch the dipstick often while doing it. If the oil gets milky pull the intake to verify its the block and not the intake only.

 

[Scott Danforth]

Thank you very much for the info. If I go with the '04 out of the pickup with accessories and the serpentine belt, eliminate the AC pump, shouldnt the alt and PS be adaptable? And then I would need to find a mercruiser vortec intake for the carb? Would the same exhaust manifolds work? And would a '04 still be a distributor HEI unit? My engine mounts are solid metal and the boat mount is rubber. I am guessing the liquid mounts would be available at the marine store.

Auto accessory drives are different than marine

The dizzy on 1998 up automotive V6's are plastic computer controlled junk. And you still have to pull the motor apart, strip it down to a short block, replace the core plugs with brass and the head gaskets and circulating pump with marine

Then you would need to source mercruiser specific accessory brackets and pulleys for 1996 and up Mercruiser 4.3s. Also need to source the propper flywheel for a balance shaft motor along with different engine mounts

Would be easier to get complete bobtail

Regarding your missing core plug on your motor, its a fluke if it saved your motor....if so, buy a lottery ticket

 

[bigtoyz]

Only after putting it thru some heavy driving close to shore, I have found out I wasnt as lucky and it is leaking. Since the motor probably is coming out, I am pulling the intake very soon to find out if I have a cracked lifter valley or just intake. Either way, because it is an older boat, Im not sure a $2000 marine motor is justifiable. The 2004 GM Vortec engine with 90K @ $400 is probably going to be the route I will take, and I do all my own work. It comes complete with all serpentine accessories.If I stay with them, eliminate the AC pump, wont I be able to adapt PS pump to Merc lines, rework the alt plugins? Wouldnt the stock PU flywheel also work? It will be freshwater only so would I need to change out headgaskets? Possibly buying/building a carb to EFI intake adaptor plate or even an aftermarket manifold? Does one exhaust manifold fit all yrs motors? Im just trying to decide the best route. An older '88-9? motor means a complete rebuild and waiting until this winter. Extra HP is not as big of an issue as getting it back into service for the kids summer. I really appreciate all the advice Ive gotten so far.

 

[Scott06]

Serpentine accessories can swap but I think you'll have the following issues to overcome- alternator needs to be marine version due to spark suppression. Ps pump I believe works if you take pressure relief or regulation valve off old marine pump as I think mercruiser uses less pressure. Flywheel if from a stick shift will work, auto flexplate not so much. Also I think your older flywheel and coupler is 12.75" vs newer having 14" flywheel so will need newer coupler
none of the truck ignition or fuel injection set up will be marine rated from a electrical spark suppression stand point, so best bet get a used vortec intake and swap your carb and igtion system over. Fresh water will also require marine head gaskets and brass core plugs.

Certainly can can be done but will take some thinking through and parts scrounging. Group here certainly can walk u through, but I'd tally up parts you may need as you may be pushing a $2000 reman longblock price w used engine plus needed items

 

[bigtoyz]

Because of price and availability, I am leaning towards the '04 pickup motor. It would come with the accessories and if Im reading this right, finding one with a manual trans flywheel will fit correctly? I would just have to buy a newer Vortec 14" coupler? The older flywheel 12.75 would not fit the Vortec motor or starter location? I would need to buy a marine Vortec intake, but my old carb and distributor will swap over? I will have to purchase new or adapt the old marine alt to run serpentine? Will the old exh manifolds bolt on or are Vortec manifolds different? I will have to convert to elect fuel pump, marine headgaskets and brass plugs. The '04 starter should be marine/spark resistant? I really appreciate all the advise and knowledge. I like going into projects knowing the pros & cons rather than pulling things and then figure it out. Thank you for making me think it through. I will also post and let you and future swappers know how things go.

 

[Rick Stephens]

Almost everything on front f the motor needs replacing.

- Marine water pumps are designed not to rust in fresh water. Automotive will have trouble lasting more than a season.

- Alternators are different, marine ones won't light off a bomb

- As noted - core plugs, head gaskets,

- intakes are a little different, usually electric chokes on marine engines, no heat riser nor any vacuum ports.

- marine carburetors are absolute must. So use your old one or buy new, but not use automotive!

- marine distributor is designed to prevent sparks, so use your original

- no machined hole for mechanical fuel pump. Wiring in an electric means you will be adding oil pressure switch, start circuit from starter solenoid and relay to power pump. Also plumbing in electric pump safely.

- I believe you will have no issue using the old fluid motor mounts with a balance shaft motor. However a couple folks with more knowledge may weigh in with better information.

 

[Scott06]

Yes the 04 will come with accessories but they aren't marine rated so don't do you any good. All automotive electrical and fuel components are not safe to use in a marine environment due to the spark suppression and fuel venting required in a marine environment.

This is why it is much easier and cheaper to get a junkyard motor of same vintage (strip to long block and swap marine accessories) or buy a rotten boat and yank complete engine as it will nickel and dime you.

i think you will will need to do the following to make this work (others please verify as I may be off):

alternator- old v belt alternator won't work with serpentine belt, non marine alternator from engine won't work either. Not sure if you can't swap pulley or will have to get marine alternator
starter if you indeed have the smaller flywheel vs the newer 14" I think you'll need a different marine starter as starter on junkyard motor isn't marine rated.
If junkyard motor is a stick shift flywheel will work just need to verify if existing coupler works with new flywheel.
Vortec intake will be required . I believe carb and distributor/ ignition system off old engine will work
electric fuel pump 04 block won't have provision for mechanical fuel pump. So unless your existing is electric already you'll need to rig an electric fuel pump.
Head gaskets and core plugs need swapping as well
need to use marine water pump off old engine no idea if this will work with serpentine system
PS pump I think you can use the serp pump if you swap the relief valve off the old marine pump.
Verify wriing harness will work with where alternator is on new motor.
Exhaust should work no issue just check for freeze damage

only point was to verify these items before you put down money on new engine. Places like Rapido Marine have reman same vintage long blocks for $1400 plus freight. Just thinking that by the time you swap all these items over you may spend more money than the reman.

 

[bigtoyz]

I ended up with a good deal on an '02 Blazer 4.3 motor. A flywheel for this motor is 14" OD, 12.6" bolt pattern, 168 tooth. All im finding is couplers for a 14" but 11" bolt pattern.Are the couplers the same or what am I missing?. Would anyone know part number or how to find a coupler for the 14" OD, 12.6" bolt pattern flywheel? The sterndrive is a mercruiser SE106.

 

[bigtoyz]

Ok, the first bit of future info I can pass on for others trying this swap, directly from Michigan Motorsz inc is that ALL marine 4.3 flywheels (1987 and newer) are the same, meaning I can use my 1988 marine flywheel and coupler on a 20?? 4.3 car or marine engine and will work properly for the application, not "just work". Im assuming because its heavier than car, that is absorbs more vibration. The 1987 and newer 4.3 marine flywheel is approx 40 lbs, I was told its heavier than the car, the crank bolt patterns are the same but the coupler bolt pattern is different than clutch pattern. So I plan to reuse my 1988 flywheel and coupler on the 2002 motor, same diam ect.

 

[bigtoyz]

I think a '88 junkyard engine up here that isnt worn out would be hard to find. After talking with Michigan Motorz, very knowledgeable, the '88 marine flywheel and coupler will swap to the '02 motor. He said auto and marine flywheels otherwise are the same which leads me to believe the '88 starter should also swap unless bolt pattern changed and then I will need to find a '02 marine starter. I have found a marine vortec 8 bolt intake, will use my '88 marine carb and distributor, '88 motor mounts, I will have to purchase 1 new marine exhaust manifold, carefully wire in a new external electric fuel pump, brass frost plugs, head gaskets, if '88 marine water pump wont swap, purchase a new marine serpentine water pump. I will adapt or purchase new marine serpentine alt and PS pump.
Overall, a reman marine engine alone was going to cost $2000+ and unsure of how long to arrive. I am thinking I will have less than $1000 into the swap and no wait, plus a vortec motor. I build street rods and have done my share of adapting components on the front of the motor to fit, and am very aware of the fire safety issues thanks to this site. I really appreciate all the help and suggestions.

 

[Bondo]

He said auto and marine flywheels otherwise are the same which leads me to believe the '88 starter should also swap unless bolt pattern changed and then I will need to find a '02 marine starter.

Ayuh,..... Welcome Aboard,..... The Beauty of Chevy swapability,....

The starter follows the flywheel diameter,......
A 14" flywheel uses the staggered bolt pattern starter,.....
A 12" flywheel uses a straight bolt pattern starter,.....
Always have, 'n hopefully always will,.....
Blocks can be found drilled for 1 pattern or the other, or both patterns,....
So bottom line is, the block determines which flywheel you can run, by which starter bolt pattern is used in any one block,....