1992 Mercruiser 4.3 w/ balance shaft and 1 piece rear main seal swap to newer year Vortec.

[nic420]

Will my current manifolds be able to swap to the new Vortec heads? Will my Mercarb 2 bbl work on the Vortec heads too?

 

[Lou C]

Yes the exhaust manifolds will work and the carb should as well, you will need a Vortec intake manifold (8 bolts vs 12).

 

[nic420]

Will the distributor as well?

 

[nic420]

My boat is a 1992 Bayliner 2252 cabin cruiser. I was wondering about a motor swap and wanted to know what Mercruiser is best to fit my current 1992 Mercruiser 4.3 w/ balance shaft and 1 piece rear main seal. I would like to use all the current accessories because they are new. Trying to get more power at the same time.

 

[nola mike]

Will the distributor as well?

Yes

My boat is a 1992 Bayliner 2252 cabin cruiser. I was wondering about a motor swap and wanted to know what Mercruiser is best to fit my current 1992 Mercruiser 4.3 w/ balance shaft and 1 piece rear main seal. I would like to use all the current accessories because they are new. Trying to get more power at the same time.

What's with with the current engine?

 

[nic420]

Cracked

 

[Rick Stephens]

Simplest is replace with the same block but with Vortec heads and intake. That's what my motor is.

The later block will not have a mechanical fuel pump mounting location, so you have to wire in electric fuel pump and do so CORRECTLY to be safe.

Newer Vortec motors all ran serpentine belts, so you have to make a swap on the damper to V belt pulleys to run your old accessories.

 

[nic420]

What's your opinion on repowering to a 5.7L?

 

[Lou C]

Simplest is replace with the same block but with Vortec heads and intake. That's what my motor is.

The later block will not have a mechanical fuel pump mounting location, so you have to wire in electric fuel pump and do so CORRECTLY to be safe.

Newer Vortec motors all ran serpentine belts, so you have to make a swap on the damper to V belt pulleys to run your old accessories.

Rick are there any other mods to be done if you are putting Vortec heads on a non balance shaft block (but with roller cam)? Pushrods rocker arms etc? Though of doing this when I did my top end overhaul but thought there was more to it so I just replaced the old heads with reman pre Vortec heads and reused the original intake...

 

[Lou C]

What's your opinion on repowering to a 5.7L?

If you have the room in front it can be done 3.5–>4” longer. You will have to use V8 manifolds, elbows are probably the same and rejet the carb to allow for the greater displacement so the engine doesn’t run too lean. Also your top speed won’t be as high as it could be due to the 4.3 gear ratio in the outdrive, not sure if propping can adjust for that.

 

[nic420]

What's your advise on repowering w/ 5.7L?

 

[nic420]

I read some where the Alpha drives can handle up to 300HP?

 

[Lou C]

Standard 5.7 is about 270 or so hp so no prob with the Alpha

 

[nic420]

Will the my current steering control work w/ the 5.7L? What can i reuse from the cracked 4.3 non vortec motor?

 

[achris]

All your accessories should bolt straight onto a 5.7. I think the flywheel housing is the same, so the transom plates and exhaust elbows are the same. What you will need are the exhaust manifold and the exhaust tubes (immediately after the elbows). All the steering, instruments and controls will be compatible...

The only question would be the drive ratio. Some 4.3s were supplied with a 1.62 drive, which would be perfect for you with a re-prop. But some had 1.81 drives, that might present a problem get a prop tall enough. If you check the ratio and tell us what you're currently turning (prop pitch), we can calculate what should work...

Chris.

 

[Scott06]

As others have said the 5.7 swap is very doable if you have 5” additional space in front of the engine. and the side motor mounts move forward bout 4.5”

I did a 4.3 5.0 swap. Took all accessories over wiring harness etc used a partial engine package from michigan motorz and added exhaust manifolds. Snags i hit were
exhaust down turn elbows are differnt on a v8
cooling hoses are different
fuel line needed to be fabbed
throttle bracket merc used for webber works perfectly with edlebrock
if you have a 090M 4.3 youll need new starter bolts, flywheel cover bolts and studs, side engine mount bolts in SAE

i kept the 1.81 drive and stepped from 19” to 21” prop works perfectly. If you are going from a 1.81 to what should be a 1.47 drive you would probably need to go up 4” in pitch and it might work otherwise get a new to you drive upper . Really dpend on the specific application load etc

 

[nic420]

Use for off shore fishing at Catalina island from Long Beach.

 

[nic420]

3-4 fishermen and a 2 scoops fiber glassed bait tank would be the load. Looking to get to the fishing ground fast.

 

[nic420]

With the load and the 5.7L motor, what could be my max speed? Should I get the regular 5.7 or Vortec 5.7?

 

[Lou C]

What’s the approx weight of the boat? Even a Vortec 4.3 & an Edelbrock performer intake would be good for about 240 hp. Most would go for the Vortec because it adds 20-25 hp. However the intake manifold gaskets were a bit more prone to leaks although this should be long past by now. Personally I’d have the above, 4.3, Vortec + Edelbrock performer intake , 4 bbl carb and at least a half closed cooling system & remote oil filter mount.
Less weight and compact if space is a concern. But sure the 5.7 Vortec will have more hp & torque...depends if the weight of the boat really calls for it.