Interchangeable parts when repowering

[Friscoboater]

Got a quick question. I have a 305/200 2 barrel carb merc in a boat that is just toast. Can I use the carb, intake, and ignition on a 350, or will the 2 barrel cause it to run lean? Not sure about the ignition either.

 

[Bamaman1]

Re: Interchangeable parts when repowering

Sure you can use those parts.

The 2 barrel carb won't make your boat run lean, but it just won't provide the power that a good 4 barrel would.

If you're planning keeping your boat long term, go ahead and put a 600 cfm Holley carb and a good torque style manifold on it. Your boat is worth getting a good engine in--especially if it's a marine 350 cubic inch engine.

 

[Pete104]

Re: Interchangeable parts when repowering

That would be a "frankenmotor"! Why starve a 350 with carb built for 305?:facepalm:

 

[Friscoboater]

Re: Interchangeable parts when repowering

Plain and simple... Cost. The intake and carb are fine, and I do not need an extra 6 or 7 hundred dollars cost on this project.

That is why I asked the question Pete.

 

[86 century]

Re: Interchangeable parts when repowering

The carb will be just fine as long as you rejet it.

I memory servers me correctly merc put two barrel carbs on some 350's you might find the proper jetting there.

 

[Pete104]

Re: Interchangeable parts when repowering

Plain and simple... Cost. The intake and carb are fine, and I do not need an extra 6 or 7 hundred dollars cost on this project.

That is why I asked the question Pete.

I, by accident down tuned a 350 once. Had a cracked head with water in the oil & so on. A guy I knew had set of heads he swore up & down were for a 350. Put them on, dialed everything in & put in the water. Pingin' & overheating like crazy. Second quess everything I did. Then I learned what casting numbers were for & what they mean!
That's pretty much why I asked about starving/running lean the 350. It's probably the easiest AND cheapist engine to get any additional HP from ever made.
Whatever you do, don't discount the fact that your gear ratio may not be right for what you are trying to accomplish. Very possible to detonate a piston or 2.

Personally, I wouldn't do it with a flat tappet engine. Your chances are better with roller lifter. Heads are where the power is with leaner fuel mixture.

 

[Don S]

Re: Interchangeable parts when repowering

Mercruiser, Volvo, and OMC (when they existed) all used 2 bbl carbs on 350's forever, even the new ones. Somehow I don't think running lean has been a problem for that many years.

 

[Pete104]

Re: Interchangeable parts when repowering

You DA man Don!!!

 

[achris]

Re: Interchangeable parts when repowering

If jetted correctly it won't run lean, just won't have the air flow to make the same horsepower as with a 4bbl. Down the track you can change just the carb and intake and be right back up there...