Outdrive gear ratio ?

[budd858]

I have twin aq125 Attached to what i think from all the pics from sealoc i have seen are 280 outdrives, and i was wondering if any one can tell me what the gear ratio is or where i might be able to find out, there are no numbers on the drives at all. I need to replace the engines and i am converting it to a single 350 chevy and i read that i need to change the ratio in the drive to compensate for the bigger engine.Is this correct ? or would i be able to use the same drives the way they are.

 

[Don S]

Re: Outdrive gear ratio ?

Yes, you need to regear the drive. You will need a 1.61 gear ratio for the V8, the 4 cylinders have a 2.15 ratio. and NO, you can't just change the props to compensate.
When you do the change, don't forget you will need to find a Y pipe for your particular transom shield.
You also MUST position the cutout in the proper place to get the drive located properly in relation to the bottom of the boat.

 

[budd858]

Re: Outdrive gear ratio ?

thank you for the info. im still looking for a y pipe. i found every thing else i need. as for the proper location of the out drive, how do i determine that? ive done all the glass work and am just about ready to cut the new hole out .

 

[Don S]

Re: Outdrive gear ratio ?

To locate the proper location, you have to locate the crankshaft centerline. There USED to be a fullsized paper template you could get that would allow you to lay out the cutout and the bolt holes. However, it's now an "Expired Part" and you can't get it any longer.
Next best thing I can offer here is a .pdf file of that template. There are dimensions on the template to layout all the necessary holes. The bolt holes have to be perpendicular to the transom, or you will never get the studs to fit. Some careful measurements and layout and you should be fine.
Here is a link to that template.

280 Transom Cutout Template