Mercruiser 260 5.7 Alpha 1 sterndrive locked up - swap out with 1.65?

[Blueghost924]

Hi, I recently bought a 1986 Regal Ambassador with the Mercruiser 260 V8 5.7L with the Alpha I / Gen I sterndrive. The previous owner took very good care of the engine, but apparently did not know about or keep up with sterndrive and bellows maintenance. We tried to start the engine and it wouldn't turn over a bit. After removing the sterndrive, the motor turned over great and started up and ran like a top. When we removed the sterndrive, the ujoint bellows had slimy gunk and whitish jelly in the bottom and was wet. Even more disturbing is that the sterndrive u-joints are rusted bad, and the drive is locked up. It's won't turn at all by hand.

I have a spare sterndrive in great shape that's been rebuilt recently by a marina (I purchased it from) with a 1:65 ratio that I was thinking about using temporarily. In looking at the Mercruiser tables, looks like the 1986 Mercruiser 260 5.7L used a sterndrive gear ratio of 1.50.

Couple of thoughts. First, for the locked up sterndrive - I'm thinking that it may be a waste of time trying to soak the locked up sterndrive in PB Blaster to see if it will turn...and I really need to start taking it apart. Second, in using my spare 1.65 ratio sterndrive, I'm going to have to re-prop to account for the higher gear ratio.

Comments or advice?

 

[achris]

What is the current prop pitch? Running the 1.65 will probably only need a 2" (one prop size) increase in pitch. But if the prop was at the lower end of the rev range with the 1.5, then you may even be good to go with that prop. The ratio change is only 10%.

Chris.......

 

[Blueghost924]

Current prop size is 14.5 x 17p. I have a spare 15 x 17p prop that is sitting around unused. BTW - I was mistaken about my spare Alpha 1 - Gen 1. The gear ratio is 1.84...not 1.65. I know that's gonna make a difference in the thought of re-propping to adjust.

 

[Blueghost924]

One thing I forgot to mention...the V8 260 engine is driving a Regal Ambassador 255XL that weighs (according to specs) around 4500 pounds.

And yes...new gimbal bearing and new bellows (all 3) are being installed as well!

 

[achris]

Ok 1.5 to 1.84 is a 22% change. For that, you will need to find a 20" or 21" prop. But if the revs were already at the lower end of the 4400-4800 spec, then consider a 19"....

Chris.......

 

[Blueghost924]

got it - thanks for the help Chris. I'm going to look for both a 21P and a 19P and see how they run,