Seafari Pre-Alpha gear ratio
 

The decal with the gear ratio stamp on my 1971 Type I (aka pre-Alpha, aka Type R) outdrive is missing. Anyone know the gear ratio on the 1969-1973 Mercruiser 140 equipped Seafari's with the older outdrive?

I've been offered a free rebuilt 1974 early Alpha 1 drive (short splined-shaft) with a 1.65 gear ratio that one of my West Marine customers has had sitting in his garage for over 20 years, and I think the ratio on my current outdrive is either 1.81 or 1.95. It makes a difference in figuring out which prop to work with.

This guy had the drive rebuilt and it was in his truck when his barn caught fire and burned the boat with it. Insurance was had.

Father, I think you can take off the top cover on the upper case,.and count the teeth on the gears to find the ratio.This chart may help.

http://www.seilermarine.com/info/mer...atio-chart.php

Padre,
My book shows the Model I early 110/140 shows 2:1

Model 140R s/n above 2791957 shows 1.98:1

Make sure the transom assembly is compatible. I found the Alpha drive was not compatible type I-C EZ transom assembly.

I don't know if simply changing out the transom assembly would allow you to go with the early Alpha which may be far easier to find parts for.'.

These ratios come from the Seloc manual because I couldn't find the info in the Mercury Manuals.

Err, are there moral implications relative to the insurance history:rolleyes:?

Let us know what you find...

Thanks!
 

Thanks! Tooth count says I have 1.98:1

I don't think so. He's not making a profit on it.

When i pulled mine out of my 20 Sefari it was a 198:1 drive. Looked to be original. That 165 ratio drive wont be right.

Yeah, I know. I'd have to radically change props to about a 16" pitch from the current 19".