1986 gimbal housing, gimbal ring, bellhousing, outdrive swap on to a 1968

[meantobe63]

Just noticed yesterday that my u-joint bellow has a slight rubbed thru mark on it from the water inlet hose. I already have the wrong drive ratio (4-cylinder drive behind a 6-cylinder) and it's off my 1969 boat, and the trim system isn't working (leaks down immediately). I have the opportunity to get my old 1986 Larson with a 170 Mercruiser (4-cylinder) I sold years ago that has a SEI drive on it and working trim system with the "power trim XD" system.

Will all the external pieces bolt to the original inner transom plate or would that need swapped as well?

I found one place online that actually listed a gear ratio for the 67-71 160's and it was 1.68:1. From what I found for the 170/470 for 76-82 (boat is a 1986) was a 1.84:1 which is still closer than the 1.98:1 I have on there currently so I am hoping it will bolt up fairly easily.

 

[Bondo]

Will all the external pieces bolt to the original inner transom plate or would that need swapped as well?

Ayuh,..... You'll need to swap everything forward of the motor to make that work,.....

 

[meantobe63]

Ayuh,..... You'll need to swap everything forward of the motor to make that work,.....

So i'd need to use the newer inner transom plate? I keep seeing 14" as the engine mount spacing but it looks more like 15" on this 160. So the 1986 inner transom plate while be the 10" space so I'd need a newer flywheel housing with the engine mount spaced to match. Or will the 170 flywheel housing bolt to the 160? Thank you.

 

[kenny nunez]

As Bondo said you will need to use everything from the engine back.
I think the 470 flywheel housing will bolt to the 160. The SEI drive should work out ratio wise. If the SEI has the longer driveshaft it should connect to the engine. The front mount will be further forward
Some early 160 powered boats did not have a 2” thick transom. I have seen one once that had a 1.5” thick transom and the plate will break before tightening against the transom. So check that.
You will have to cut out some of the transom on the port & starboard sides and drill 2 new holes. Use it as a drill guide for the 2 new holes. You must use the 86 model inner plate. The exhaust will take some creative work as the 470 exhaust pipe is much larger, the original pipe will not mount to the 470 gimbal housing.
Be sure to use the 470 hydraulic system also.
I cannot think of anything else right now, so get started.

 

[meantobe63]

As Bondo said you will need to use everything from the engine back.
I think the 470 flywheel housing will bolt to the 160. The SEI drive should work out ratio wise. If the SEI has the longer driveshaft it should connect to the engine. The front mount will be further forward
Some early 160 powered boats did not have a 2” thick transom. I have seen one once that had a 1.5” thick transom and the plate will break before tightening against the transom. So check that.
You will have to cut out some of the transom on the port & starboard sides and drill 2 new holes. Use it as a drill guide for the 2 new holes. You must use the 86 model inner plate. The exhaust will take some creative work as the 470 exhaust pipe is much larger, the original pipe will not mount to the 470 gimbal housing.
Be sure to use the 470 hydraulic system also.
I cannot think of anything else right now, so get started.

Thank you Kenny. The main reason to do swap is for the newer trim system. I guess I'll do some more research to hopefully confirm the 470 housing will bolt to the 160. I can fabricate something for the exhaust hopefully as long as there is a decent gap between the 160 elbow and the 470 transom exhaust tube.

Not really looking to pull engine out but might just have to. Thanks for the transom thickness info. It's a 1968 Glasspar Flying V

 

[meantobe63]

As Bondo said you will need to use everything from the engine back.
I think the 470 flywheel housing will bolt to the 160. The SEI drive should work out ratio wise. If the SEI has the longer driveshaft it should connect to the engine. The front mount will be further forward
Some early 160 powered boats did not have a 2” thick transom. I have seen one once that had a 1.5” thick transom and the plate will break before tightening against the transom. So check that.
You will have to cut out some of the transom on the port & starboard sides and drill 2 new holes. Use it as a drill guide for the 2 new holes. You must use the 86 model inner plate. The exhaust will take some creative work as the 470 exhaust pipe is much larger, the original pipe will not mount to the 470 gimbal housing.
Be sure to use the 470 hydraulic system also.
I cannot think of anything else right now, so get started.

I did just look and see the transom is most likely 1.5" and there is another board in between inner plate and transom, haha.