Alpha one compatability

[Han Solo]

Have a mercruiser 260 i/o, and was woomdering if a drive from the 3.0 would fit and work. I understand the gear ratio is different, that should just affect top end speed. Would the drive from the 4 cylinder handle the power of the 260?<br />Thanks

 

[Bondo]

Re: Alpha one compatability

was woomdering if a drive from the 3.0 would fit and work.

Fit?,..........Ayuh........Work?,....... Nope........<br />

that should just affect top end speed.

Nope.......... It Affects Everything ..........<br />You'll be running 5000rpms@ 15mphs......<br />There'll also be too much torque at the prop,+ It'll Ventilate......<br />

Would the drive from the 4 cylinder handle the power of the 260?

Sure........... After you change the Upper Gear set to the Right Ratio..........<br /><br />BTW, Welcome to iboats forums..............

 

[WillyBWright]

Re: Alpha one compatability

If you're pushing a big boat with it, I like the ratio of the 3L Alphs better. MerCruiser sells all their drives and motors as packages. The same setup powers a 19' ski boat to a 36' Cabin Cruiser. Why not have different gear ratios appropriate for the job? They do it for vehicles.

 

[TilliamWe]

Re: Alpha one compatability

Bondo, a gear change may not be absolutely necessary. The correct prop would change the overall gearing. However, it's a big change that's needed. Your drive behind that 260 has a 1.5 to 1 ratio. That 3.0l drive will be 2 to 1. (Is that 3.0l ratio correct, Bondo?)<br />But Han Solo, you would need a high pitch prop in order to make the engine not turn 5000rpm at 15mph (that is a exagerration, but a good one to illustrate way-too-low gearing). The search for the "right prop" would open up a whole new can of worms.<br />My advice, for what it's worth, is to get the same ratio outdrive that the 260 came with originally. It'll be much simpler, less aggravating, and I'll bet less costly in the end. Good luck

 

[Bondo]

Re: Alpha one compatability

Ayuh.......... I was exaggerating a little... Though not as much as you may Think.....<br /><br />The Problem will be that Standard, Easy to Find Props run from about 15"s of pitch to about 23"s.............<br />A 350cid, 5.7l, with a 1.98/1 ratio, will require a prop substantially Larger than is Readily Available.......<br /><br />And,<br />You'll Still have the Too Low a ratio,+ consequently Too Much Torque, causing ventilation.........

 

[TilliamWe]

Re: Alpha one compatability

The Problem will be that Standard, Easy to Find Props run from about 15"s of pitch to about 23"s.............<br />A 350cid, 5.7l, with a 1.98/1 ratio, will require a prop substantially Larger than is Readily Available.......<br /><br />And,<br />You'll Still have the Too Low a ratio,+ consequently Too Much Torque, causing ventilation.........<br />

Bondo and Han Solo, this was the "whole new can of worms" that I spoke of. <br />I just didn't want to bombard Han with all the info at once.

 

[muc]

Re: Alpha one compatability

I think you will need to change the input shaft also. The 4 cylinder drives only engage the first 1 inch of the V8 coupler and will strip it out.

 

[Bondo]

Re: Alpha one compatability

Ayuh............<br /><br />You're Right about that muc.... That's Another 1 of those Worms in the Can........<br /><br />The "In-Line" motors(about 8"s) use a Shorter Input Shaft than the V-motors(about 9"s)........

 

[TilliamWe]

Re: Alpha one compatability

Bondo & muc, thanks for that info on shaft length. I learned something new today. I just thought the bell housings, the couplers, or where the motors were mounted took up any difference in length needed.<br />Han, you idea looks more & more complicated all the time. If you already own a drive from a 3.0l, sell it, and use the money to but the correct drive for your 260. Best of Luck