Swapping gearing in a stringer outboard

S

Sheehandler24

Seaman Apprentice
Joined
Jul 19, 2023
Messages
36
I bought a boat with a 3.0 140 and the guy previous swapped the outboard to a 165, I’m not sure this is okay. He gave me the old 140 outboard. The 140 has a damaged lower gear casing (the fin is broken off) but the internals are fine. Can I take the internals out of the 140 lower unit and swap them into the 165 lower gear case? Or would the upper and lower gear ratios clash?
 
Scott Danforth

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
50,249
much easier to simply weld on a new skeg on the 400 lower

you are trying to mix stringer 400 and 800 bits.
 
K

kenny nunez

Captain
Joined
Jun 20, 2017
Messages
3,330
This must be an electric shift drive. If it is then all electric shift models have the same gear ratio in the lower gearhousing. The upper is where the ratio is determined. The last 165 hp inline 6 was made in the mid 70s.
Do as Scott said get the skeg welded on the 3.0 drive. Be very careful with the shift wire not to damage it.
The 165 drive might work with lower pitch propeller. 4-4400 rpm is the what you want to end up with.
If the steering is internal make sure that both drives are “straight ahead” if you swap the drives.
 
S

Sheehandler24

Seaman Apprentice
Joined
Jul 19, 2023
Messages
36
Yeah I looked up the gear ratios on the two and they’re really not far off from each other. The 140 has a 19-20 gear set and the 165 has a 21-19 gear set. It doesn’t seem to bog down or anything on the water, just won’t go over 3200 rpm. The 165 leg is in waaaaay better shape so thats why I’m hesitant to get rid of it, I think I’ll run it for now and get the skeg welded in the mean time. If they have identical lowers I could probably just pop the 140 upper onto the 165 lower unit? Idk just spit balling
 
K

kenny nunez

Captain
Joined
Jun 20, 2017
Messages
3,330
Swapping the upper will work. Just be sure that the steering gears are set so that you get full swing in both directions.
 
S

Sheehandler24

Seaman Apprentice
Joined
Jul 19, 2023
Messages
36
Cool, well that’d be relatively easy. Other than the fact that I’m gonna have to cut that wire some where to take it off. The guy before crimped and shrink’d them together
 
K

kenny nunez

Captain
Joined
Jun 20, 2017
Messages
3,330
Try to separate them inside the boat. They must not be repaired where they will get wet. Galvanic action will burn them out very quick.
 
S

Sheehandler24

Seaman Apprentice
Joined
Jul 19, 2023
Messages
36
jimmbo said:
You won't like what I would recommend, regarding sinking any money or time into a Stringer I/O
Click to expand...
Yeah I realize what I have isn’t ideal but I’m not sinking any money in. I have exactly what I need to swap it to the proper gear set. I love this boat, the engine is a good runner and everything works great as far as the leg is concerned. It’s just geared a little too high to get to its proper WOT. I don’t think it’s hurting anything but it’s not optimal. As far as parts go eBay is teaming with them. The boat it’s self is a good old riveted aluminum StarCraft and if this engine and leg go to hell I’d totally be willing to restore and re-power.
 
S

Sheehandler24

Seaman Apprentice
Joined
Jul 19, 2023
Messages
36
Well I wound up taking the gears from the 140 and and tossing them into the 165, everything fits and turns great. I have yet to test it out on the lake but I’m hoping it holds up. Put new bearing seals and O rings in through out, hopefully she doesn’t explode 🤞
 
Scott Danforth

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
50,249
Did you set up the gears per the factory manual? If not, make sure to have a tow ready
 
You must log in or register to reply here.
Top