bf225 lower units interchangable?

Can a right hand lower unit be swapped for a left and vise versa? I would like to do this with a set of BF225 engines to make one engine out of the best parts. Any insight would be appreciated.

I'm not the expert, but I believe the engine functions the same. It is only the LU that determines whether it is normal or counter. In other words, the drive shaft spins the same way.

Thanks, That was my impression as well. I just began to question a bit when the alignment pin was on the port engine and the starboard LU. I was able to remove the pin from the LU, so I figured the pin just separated from different pieces on each engine.

Those lower units will need different props

Thanks, I have two complete engines with props, so I just swapped the whole lower unit. Are there any other parts that should be changed along with the LU? Anything else I should know before I go out and run the engine?

Better wait for a solid answer, just to be sure. I wouldn't guess at this.

So are you going to have a boat with 2 of the same LU rotating the same direction? I think catamarans do this.

Good question, I have a single engine boat but I picked up a couple of outboards from a twin engine boat that was being re-powered.

Very good question, I have on of my own that no mechanic has been able to answer. Fountain 42 ft.ocean racer,3 502s starboard side r/h port side l/h, What rotation does drive in the middle turn? Or does it matter?

Intuitively, I'd say right hand for the middle engine. Although, if you could have one of those LU with counter rotating dual props on the middle engine... might be sweet. I Drove a twin engine boat with dual counter rotating props on each engine and it grabbed the water like nothing else. Those were I.O.'s.

To follow up that thought, why is right hand rotation the standard for single engine boats? Is it just convention, or is there a slight hydrodynamic advantage. Or, possibly a mechanical advantage for that matter, based on the way we design the engines. In water, vortices shedding tends to be to the right, and Im not talking large scale like coriolis, which is related to the earths rotation. More questions than answers, but there you go. I'd be curious to hear what others think. Or to get back to my original question, anyone out there that can advise if there are other considerations when changing lower units? should I swap stabilizer bushings, etc. etc.? Or am I good to go?

The lower units can be swapped without issue if they are of the same year of manufacture. When they differ in years, there can be a difference in the shift shaft from the gearcase to the upper part of the engine.

The other questions.....

The middle engine, according to the Honda Rigging Manual is supposed to be right handed.

As for why right hand rotation single engine......one reason could be...the torque of the prop/engine causes the bottom of the engine to rotate counterclockwise, thus the boat to rotate counterclockwise. That torque is generally offset due to the driver and console being on the starboard side of the boat. I know that does not explain center counsoles. Most all single prop inboard/outboards that I have seen are right hand, except for the older volvos and probably many that I have never seen.

One issue with using a counterrotating prop on a single engine is....there is not an easy way to adjust the trim tab to help offset steering torque. I have seen a few customers who use counterrotating Hondas, and they seem to do just fine.

Just my thoughts....

I will bet Jimmy could give us the true "physics" of why right hand rotation....

Mike

Thank you for the info! The engines are from the same year, glad to know I'm ok with the switch.