1995 bayliner 1850 4.3xl motor swap

[MTPIII]

Hey everyone I’m new to this site and figured I would try it out. I’m trying to figure out if a 2003 4.3 out of a s10 will match up and have the same vintage as my 1995 4.3 in the boat now... I already have everything to replace and make it marine just wondering if the years are too far apart

 

[Scott Danforth]

no, however it can work

your 2003 motor is a vortec head, 1-piece RMS crank motor with a balance shaft and no location for mechanical fuel pump
your 1995 is a non-vortec head, 1-piece RMS motor, with a balance shaft and should still have a mechanical fuel pump

you will need a 1996 and newer vortec intake manifold.

change the new motors core plugs to brass and the head gaskets to marine.

here is some reading on the 4.3's https://forums.iboats.com/forum/eng...history-of-the-4-3-liter-with-casting-numbers

 

[MTPIII]

Ok so the intake I have on the motor now won’t work? And so I just need a intake gaskets bass plugs and what about the cam?

 

[Scott Danforth]

correct, your '95 intake has 12 bolts at an angle, 96 and up have 8 vertical bolts

truck cam is fine (really close to marine cam)

 

[AShipShow]

Scott, my 95 had an electric fuel pump, so that must be right around the switchover.

Theres also a bunch of odds and ends you will need to swap over... I think everything converts but I could be mistaken... I believe the s10 motor will have a serpentine belt, so you will need to swap over the pulley, and if its an automatic transmission, you will need to swap over the flywheel which SHOULD bolt up.
I recall running into a few other issues on mine, but it was all reasonably straight forward...

I will tell you though, it is MUCH easier if you get the same vintage motor. That being said, vortec heads are a good investment. So there are pros and cons to weigh out.

 

[Scott Danforth]

Scott, my 95 had an electric fuel pump, so that must be right around the switchover.

Theres also a bunch of odds and ends you will need to swap over... I think everything converts but I could be mistaken... I believe the s10 motor will have a serpentine belt, so you will need to swap over the pulley, and if its an automatic transmission, you will need to swap over the flywheel which SHOULD bolt up.
I recall running into a few other issues on mine, but it was all reasonably straight forward...

I will tell you though, it is MUCH easier if you get the same vintage motor. That being said, vortec heads are a good investment. So there are pros and cons to weigh out.

please stop giving bad advise

the automotive S-10 circulating pump cant be used, only the marine ones survive (brass impeller, stainless rear cover)

the accessories from the S-10 get thrown away because none of them can be used. in a marine motor Mercruiser makes their own brackets, so does Volvo and so did OMC. all electrics are marine specific.

to use an automotive engine, you strip it down to the block and heads, leaving the rotating assembly in-tact, then build back up as a marine motor. the only thing you can use is the long block and flywheel if its a manual transmission and you have to change the core plugs and head gaskets. none of the bolt-on bits from an S-10 are retained. all that is specific to whether its an OMC, Volvo, or Mercruiser.

your 95 block could have either mechanical or electric fuel pump. 96 and later have no mounting boss for the fuel pump.

 

[Bondo]

the accessories from the S-10 get thrown away because none of them can be used. in a marine motor Mercruiser makes their own brackets, so does Volvo and so did OMC. all electrics are marine specific.

Ayuh,..... That's why I always say the Long Blocks will interchange,.....

Not complete, or even nearly complete motors,.... Only the Long Blocks,...

 

[MTPIII]

yes agreed I will be striping it down and using only marine parts and as well my 95 has electric pump but I can make a bracket for it that’s not an issue my concern was cam and intake but Scott you have answered my questions ..... but let me ask you this when the water mixes with the oil and comes up through the pvc on the valve cover the valley is probly cracked?

 

[achris]

GM stopped the mechanical fuel pump on the 4.3 Generation 2 blocks (which is nothing to do with the Gen II drives :facepalm, which Merc started using in 93... Any 4.3 '93 and later will ONLY be able to use an electric fuel pump, and as such must have the right engine electric harness to use an oil pressure switch in the fuel pump power circuit.

Wet oil coming from the valve covers is a crack from the water jacket to the inside of the engine, valley is one possibility. Usually caused by poor winterizing. Any crack that allows cooling water into the engine oil is a reason to condemn the block.

If your old heads are still good, they will bolt onto the 2003 block, but I would keep the existing (2003) heads and get a manifold to suit..

Chris.........

 

[MTPIII]

Yes will do I will be picking up the motor this weekend so wanted to get into detail before pulling the trigger on thanks Scott and a Chris you guys have been super helpful p

 

[MTPIII]

Scott there’s one last thing I was looking through the link you sent for the 4.3 now I can’t find my 4.3lx in the year 1995 I might be possibly reading it wrong but my motor has a electric fuel pump and I’m trying to figure out if it’s a 2bbl or a 4bbl or is it possible it’s tbi?

 

[achris]

If it's a 4.3LX, then it's a 4 bbl. An engine serial number would clear it up definitively.

 

[MTPIII]

I have a pic of it when it puked oil and water but it won’t let me upload any ideas? And also I know we were talking about Vortec heads I looked at my pics and the valve cover says Vortec already wanted to see what you guys thought about that as well

 

[Scott06]

Vortex was used on the 4.3 prior to vortec heads coming out. If the intake manifold has 8 bolts fastening it to the heads it's a vortec if it has 12 it is not a vortec.

 

[MTPIII]

Oh ok that makes sense trying to find the 8 bolt intake manifold hasn’t been the easiest yet ok also as far as prepping the new block is there anything else I have to change besides the things noted already I just want to double check before getting into this

 

[AShipShow]

If you are running in fresh water only, then pickup an Edelbrock 2114 intake manifold. If you are going to run in salt at all, it will ruin your aluminum intake in short order so you will need to find a 8 bolt style mercruiser manifold or edelbrock 2519 which has brass lined water passages.

 

[Bondo]

Ayuh,..... I think Michigan Motors sells the cast iron intakes,.....