1990 Merc 4.3 and 1995 Merc 4.3LX

yamhoss86

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Hello all, just a couple of Merc 4.3 questions.
What is the difference between the two besides the 4bb carb?
Can the 1990 be mounted in the same position as the 1995?
Thanks in advance.
 

Scott Danforth

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Hello all, just a couple of Merc 4.3 questions.
What is the difference between the two besides the 4bb carb?
Can the 1990 be mounted in the same position as the 1995?
Thanks in advance.

one is 5 years newer. other than that, the 1990 is pre balance shaft, the 1995 has a balance shaft. they can be mounted in same location, just use the correct motor mounts for the correct motor.

are you looking to replace a bad 1995 with a 1990? If so, look for a 1993 or later to get a balance shaft. you can get a low mileage long block from a u-pull-it salvage yard for under $300
 

yamhoss86

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.one is 5 years newer. other than that, the 1990 is pre balance shaft, the 1995 has a balance shaft. they can be mounted in same location, just use the correct motor mounts for the correct motor.

are you looking to replace a bad 1995 with a 1990? If so, look for a 1993 or later to get a balance shaft. you can get a low mileage long block from a u-pull-it salvage yard for under $300


Thanks for the feedback.
Is there anyway to make the 1990 balanced?
I already have an offer for a 1990 4.3 for a great price.
 

Rick Stephens

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I believe the 95 is a Vortec while the 90 won't be. Nothing wrong with going backwards, but you'll be dropping a bit of horsepower. Heads and intakes are different between Vortec and pre-Vortec heads. Balance shaft is built into the block and not something you can add to an earlier model block. I would not consider the balance shaft an issue either way. The Vortec heads and intake is a big deal, to me. I would want to keep a Vortec in there.

Rick
 

thumpar

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You will have to verify the Vortec in 96. It was a crossover year for boats. I would for sure look for a Vortec.
 

yamhoss86

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You will have to verify the Vortec in 96. It was a crossover year for boats. I would for sure look for a Vortec.


Thanks for the info, will the Vortec fit in the same mounting positions as a pre-vortec 4.3?
 

Rick Stephens

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Thanks for the info, will the Vortec fit in the same mounting positions as a pre-vortec 4.3?

Short answer is yes. The flywheel housing bolt pattern is the same, the motor mounts are the same. Pretty much externally an identical motor. Even the exhaust is the same.

What's different is the heads and intake. And along with the heads is different pushrods, rockers and usually roller cam instead of flat tappet, although I think they stuck rollers in the motor starting in like 89 or 90.

If you find a nice Vortec motor, go for it. The heads are a nice step up in HP and the differences are minor if you are starting with a complete Vortec motor. Pretty much everything will pull off your old motor and bolt to the new one.
 
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Scott Danforth

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Volvo motors only vary by their cam choice
 

yamhoss86

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Ok so the boat that i purchased had a 1995 Merc 4.3LX.
The boat has no engine or out-drive, just the transom assembly for an Alpha 1.
I am planning to get a 1998 Merc 4.3 with an alpha outdrive.
My question is, will the 1998 4.3LX fit in the same place as the older motor did?
Do i need to change the transom assembly?
 

yamhoss86

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​Hey guys, so i purchased a re-manufactured engine, see pic attached/below.


Merc 4.3.jpg

I got a 1988 Merc 4.3 for $100 so i can switch over the parts.

I asked a local marina store of mine to give me a quote to install the new engine and shift over the parts and wire the boat.
The guys Quoted me $2700.00 for everything.

$800 to switch over all the parts.
$1900 for the installation and wiring

I think i can just rent a engine hoist and do it my self.
What do you guys think? is this Quote high, low or just right?

Thanks.
 

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Bondo

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I got a 1988 Merc 4.3 for $100 so i can switch over the parts.

Ayuh,.... Yer picture appears to be a Vortec motor,...

The intake manifold, 'n mechanical fuel pump from the '88 won't fit the newer motor,....

$2700. sounds pretty high for that work, why not do it yerself,..??
 

yamhoss86

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Ayuh,.... Yer picture appears to be a Vortec motor,...

The intake manifold, 'n mechanical fuel pump from the '88 won't fit the newer motor,....

$2700. sounds pretty high for that work, why not do it yerself,..??


The new motor comes with an Intake Manifold.
I do need to purchase the electric fuel pump.

I'm thinking about doing it myself.
I'm just scared about the wiring, that i will mess it up.
Also, where/how would i need to adjust the height of the motor so that the alignment tool can line up. Should i adjust the front/rear mounts?
 

yamhoss86

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Another questions, would a 1998 5.0 MPI fit in the transom assembly that a 1995 Merc 4.3 used to be in?
I have a good deal lined up for the 5.0 MPI but need to know if the motor is compatible.
Thanks guys.
 

Bondo

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The boat has no engine or out-drive, just the transom assembly for an Alpha 1.
would a 1998 5.0 MPI fit in the transom assembly that a 1995 Merc 4.3 used to be in?

Ayuh,..... 'bout any motor set up for an Alpha, later than 'bout '83, will bolt right up,...
 
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