Easiest Conversion

[Rranger]

From Mercruiser 170. What's the simplest different mercruiser engine to drop in if there is one where the engine would bolt up to the 170 throughhull and drive? Or simplest total replacement with minimal stringer and engine mount add ons? Thanks.

 

[Faztbullet]

140 4 cylinder but gotta change gear ratio

 

[Rranger]

140 4 cylinder but gotta change gear ratio

Thanks I just noticed this is in the wrong category hopefully a mod changes it. I appreciate your answer but can you tell please tell me what’s involved changing the gear ratio. I’m leaning towards rebuilding the 170 but checking options. Thanks.

 

[matt167]

Just buy a 1.98 leg off of Facebook marketplace or SEI. You might be able to prop it close enough to work with what you have.

I would drop in a 3.0L until you have time to make the switch to a 4.3L which is more involved. 3.0s are cheap and that will get you back on the water. A good used 3.7 is an option too but finding good ones is hard. 3.7 parts are drying up. You can rebuild the bottom end but the marine specific parts are hard to find

 

[Scott06]

From Mercruiser 170. What's the simplest different mercruiser engine to drop in if there is one where the engine would bolt up to the 170 throughhull and drive? Or simplest total replacement with minimal stringer and engine mount add ons? Thanks.

Mercruiser 3.0/140 you will loose some power. If more power than 3.0 is needed do a 4.3 but that will involve stinger work and is wider.

on a 3.0 drop 2” of prop pitch u should be able to use existing drive

 

[Scott Danforth]

Easiest will be to use another 470.

A 3.0 will require remaking t front mount. A V6 will require new side mounts.

If the boat is 15-18 ft, the 3.0 will be fine. However it is about 140# heavier

If the boat is 18-21 ft, I would go 4.3 minimum

With a bit of looking you can probably find a full longtail

 

[Pmt133]

A 3.0l pushed around my boat for nearly 40 years. It'll do it. But if it was marginal with the 170 it'll be worse with the 3.0l. I had a good running 470 I was going to swap in against my better judgment and then wised up and went with a 4.3l. It took a while to plane. Once it got up you were fine. My mount was large enough to accept the 470 without modification also so it could be as simple as drilling new mount holes for the 3.0l... provided the wood isn't rotted out.

I'll also add I know of a guy with my exact boat with a 490? (4 barrel version), it runs 1 mph slower on the top end compared to the 4.3l. The 4.3l comes on and up to plane much quicker and is quieter. No comparison between the two.

 

[Rranger]

This is it. Has the 470 in it. Does the 3 front new cross member fit inside the present engine berth or do I have to extend the berth opening forward?

 

[Rranger]

I also do have this 14 degree pod and this glass ply boat transom measures 14 degrees, and have a 125 hp merc outboard. And a 9.9 4 stroke Yamaha kicker. Or find a suitable Mercruiser complete unit for the glass ply and then carry on with the transom, floor rebuild I’m half way through on the bellboy and put the pod back on it and the engines. Love the hardtop on the glass ply for all the crap weather fishing I do, so probably leaning towards it being the boat I’d keep. So basically having a look for Mercruiser setups out there and then decide on best option for power..

 

[Scott Danforth]

This is it. Has the 470 in it. Does the 3 front new cross member fit inside the present engine berth or do I have to extend the berth opening forward?

3.0 is shorter than the 3.7

 

[Rranger]

3.0 is shorter than the 3.7

3.0 is shorter than the 3.7

And that is why a new front mount is required?

 

[Scott Danforth]

yes

 

[Rranger]

One more rookie question subbing an entire 4.3 setup for the 470 would require what engine support adapts? I’ve been getting some mixed answers, and boat is 19.5 and a heavy hull. I also have a line on a 165 Mercruiser. What about it for engine support adapts?

 

[ScottinAZ]

the 4.3 uses mounts on the side of the engine, whereas the 3.0 and 3.7 use a mount on the extreme front. as far as I know there are no adapters, you just fabricate mounts to fit the engine you choose to put in, and fiberglass them to the hull. same as the original MFG did.

 

[Lou C]

A 4.3 will need side mounts in front just like a V8 except 3.5” shorter. If the engine compartment is wide enough for the V6 it would be a very good power source for a boat that size. Shorter but wider than the 4 cyl but with much more low end torque.

 

[Rranger]

What about this Volvo 4 cylinder any issues with the motor mounts and hole? Can get the complete setup key to prop.

 

[Scott Danforth]

What about this Volvo 4 cylinder any issues with the motor mounts and hole? Can get the complete setup key to prop.

you are going from an obsolete motor with a mercruiser to an obsolete motor with a volvo that you have to redo your transom to fit?

find a 1996 or newer mercruiser 4.3 with a A1G2 drive or a 1996 or newer Volvo with the SX drive.

dont keep looking at old obsolete stuff.

 

[Rranger]

you are going from an obsolete motor with a mercruiser to an obsolete motor with a volvo that you have to redo your transom to fit?

find a 1996 or newer mercruiser 4.3 with a A1G2 drive or a 1996 or newer Volvo with the SX drive.

dont keep looking at old obsolete stuff.

10/4 thanks. Been looking but they are scarce.

 

[Scott06]

10/4 thanks. Been looking but they are scarce.

You probably gotta buy the junker boat with it.

 

[Rranger]

You probably gotta buy the junker boat with it.

I've been looking for that.