Mercruiser 3.0L conversion to LX

[Dallmanator]

Hey guys thought this would be an interesting topic to cover. Most MCM 3.0 that I can find on the web are claimed to be the 135-140hp version, and nobody seems to have the 115hp model except me. How do I know I have this model.....engine model code for starters, head spark plug hole depth and of course the 36mm throat on the carb. I have a 1991 Bayliner with the 115hp model installed, I know that MCM 3.0 owners are always looking for more power and that it is sort of a running joke but if a guy can just change the head and carb (The intake comes in 3 flavors and all are installed on both models) to gain the extra 20hp especially on a 2000lb boat could be a nice fairly cheap upgrade. The only thing I am not positive on is the REAL difference of the two heads....eg. valve size, port size...ect.

So if anybody has any info on this I'm sure there would be many 115hp owners willing to listen.

Thanks!

D.

 

[Dallmanator]

Re: Mercruiser 3.0L conversion to LX

Hummmmm.....interesting, thought this would be a topic that would really take off. I do believe that if nobody has anything intelligent to say that it is better to not say anyting at all. This same post got 9 replies over at Bayliner owners club, and to tell you the truth there more information here with no posts.

D.

 

[Bondo]

Re: Mercruiser 3.0L conversion to LX

and to tell you the truth there more information here with no posts.

Ayuh,.... Welcome Aboard....

It's my take on th various HP ratings of the 3.0l come from When, Where,+ How the manufacturers are posting the #s...
The 3.0l was a 140hp way back in the 70s....
Since then it's been rated at Everything in-between the 115hp you have to 130hp, 135hp,+ 140hp...
If you figured out it's the small Carb,... Try a Bigger 1,... I doubt you'll Feel the difference,...
But, you'll have bragging rights at the dock...
I'm sure if you found the Right head,+ the Right intake,+ the Right carb,... You'll no doubt get atleast 140hp...
For Most of Us,... Swapping to a Bigger motor, or a Bigger boat just works Better, Easier...
Of course the Pay-off is Bigger too when going from a 175hp V6 to a 225hp V6, or a 200hp V8 to a 300hp V8...

It's all just Numbers anyways,... Very few motors are ever Dyno'ed to actually know the True Horsepower....

 

[ErieRon]

Re: Mercruiser 3.0L conversion to LX

Yeah, what Bond-o said, plus...download manual #13 from the link below. I think the spec's. you are curious about are in there.

 

[zbnutcase]

Re: Mercruiser 3.0L conversion to LX

The late 8-port head is by far the best one yet. You are on the right track. 'nutcase