Mercruiser 305 to 350 swap

[jehlinge]

I have a 2006 Bayliner with a Mercruiser 305 motor. The time has come to replace it. I have searched the forums here and it seems a pretty common recommendation to replace the 305 with a 350. However, in most threads, this conversion is done on older boats with carbureted fuel supply. It seems that the carburetor can be adjusted to supply the extra fuel for the 350.

My boat uses throttle body injection. Would I have fuel delivery problems if I switch to a 350? It seems like I would need some of the "electronics" in the fuel system replaced or reprogrammed to change the fuel supply.....which leads me to believe it would just be easier to stick with a 305 engine.

Anyone thoughts/recommendations would be greatly appreciated?

 

[Bondo]

Re: Mercruiser 305 to 350 swap

I have a 2006 Bayliner with a Mercruiser 305 motor. The time has come to replace it. I have searched the forums here and it seems a pretty common recommendation to replace the 305 with a 350. However, in most threads, this conversion is done on older boats with carbureted fuel supply. It seems that the carburetor can be adjusted to supply the extra fuel for the 350.

My boat uses throttle body injection. Would I have fuel delivery problems if I switch to a 350? It seems like I would need some of the "electronics" in the fuel system replaced or reprogrammed to change the fuel supply.....which leads me to believe it would just be easier to stick with a 305 engine.

Anyone thoughts/recommendations would be greatly appreciated?

Ayuh,.... Welcome Aboard,.... You'll need the 'puter for a 350,....

 

[jehlinge]

Re: Mercruiser 305 to 350 swap

Any cost effective ways of getting the 350 computer? Seems like they run about $1000 new.

Is it smart to buy these used from ebay?

 

[81 Checkmate]

Re: Mercruiser 305 to 350 swap

Just a suggestion…..you could always go with a marine carb set –up and a new marine electronic distributor.

 

[Bifflefan]

Re: Mercruiser 305 to 350 swap

Just a suggestion…..you could always go with a marine carb set –up and a new marine electronic distributor.

^^^^^^^^^^^^^^That's more than the thousand for a new brain box.^^^^^^^^^^^^^^^^^^^

Ebay ones should fine, just get one with a warranty.

 

[81 Checkmate]

Re: Mercruiser 305 to 350 swap

^^^^^^^^^^^^^^That's more than the thousand for a new brain box.^^^^^^^^^^^^^^^^^^^

Ebay ones should fine, just get one with a warranty.

Well that would all depend on where you are shopping^^^^^^^^^

I bought a brand new marine Elect Mallory Dist with a wire set for under $400.00 bucks off ebay and also bought a used marine 4 barrel Q-jet of C.L. for 75.00 bucks.

Just throwing out another option for the O.P.

 

[jehlinge]

Re: Mercruiser 305 to 350 swap

Thanks everyone for your input so far.

As yet another option....what if I just stay with a 305?

Other than the engine ingesting water (which lead to the engine's demise) I am happy with it. I normally cruise around at a nice easy pace so I am not worried about top end speed. I opened it up one time just to see how fast she would go. And even though we aren't as young as we used to be, me and my buddies still think it is a good idea to water ski. Last summer it pulled my 240 pound buddy out of the water on skis with myself, and 4 other adult males in the boat.....so the 305 didn't seem to lack in power for what I need. I guess what I am saying is that I am not in the "bigger is better" camp when it comes to the motor for this boat. I am more in the "I just want to enjoy being on the lake" camp.

Other than the gain in power are there other advantages in going to the 350? Is the 350 just a better motor where one could reasonably expect less trouble with it over the long run?

Thanks again for all your input

 

[Bondo]

Re: Mercruiser 305 to 350 swap

Thanks everyone for your input so far.

As yet another option....what if I just stay with a 305?

Other than the engine ingesting water (which lead to the engine's demise) I am happy with it. I normally cruise around at a nice easy pace so I am not worried about top end speed. I opened it up one time just to see how fast she would go. And even though we aren't as young as we used to be, me and my buddies still think it is a good idea to water ski. Last summer it pulled my 240 pound buddy out of the water on skis with myself, and 4 other adult males in the boat.....so the 305 didn't seem to lack in power for what I need. I guess what I am saying is that I am not in the "bigger is better" camp when it comes to the motor for this boat. I am more in the "I just want to enjoy being on the lake" camp.

Other than the gain in power are there other advantages in going to the 350? Is the 350 just a better motor where one could reasonably expect less trouble with it over the long run?

Thanks again for all your input

Ayuh,.... Other than displacement, they're the Same motor,...