Alpha One upgrade with 454 ?

[Agoose]

Hello All,
I have just bought a 1986 Century Meridian. It was repowered in 1992 with a Marine Power Inc 454 but the outdrive was not changed. It still has the original Alpha One. The boat weighs about 4500 lbs., more with the water and gas tanks full. My question is if there was a way to upgrade the Alpha One without going to a Bravo?
The Alpha One is stamped with these markings,(I 508) and,(OB415926). I could leave it the way it is now because it cruises at about 35 mph at three quarter throttle. I need to replace my prop. because the stainless steel one has a spun bushing. The prop. is 15 and a quarter inch with a 17 pitch. Should I think about changing the prop. at all.
Any assistance would be greatly appreciated.

 

[Don S]

Re: Alpha One upgrade with 454 ?

There are no upgrades for the Alpha. It was, and still is, only good for about 300 hp. Merc only used the 454's a few years because they wouldn't stay together. That is when the Bravo drives came out.
As far as props go, the determining factor to start with is WOT (Wide Open Throttle) rpm's. What are they?
After that, you need to post your question in the Prop forum, you will probably get better answers there.

Here's a quick link to the prop forum:

http://forums.iboats.com/bbBoard.cgi?a=viewforum;fid=40

 

[Agoose]

Re: Alpha One upgrade with 454 ?

What do you mean they wouldn't stay together?
As far as the WOT, I was told by a boat mechanic that it was 4600 rpm's. When I had going 35 mph the rpm's were around 3300. I doubt that with the little throttle I had left that it would have got up to 4600.

 

[Don S]

Re: Alpha One upgrade with 454 ?

What do you mean they wouldn't stay together?

Just that. Gear failure, shaft failure, bearing failure.

As far as the WOT, I was told by a boat mechanic that it was 4600 rpm's. When I had going 35 mph the rpm's were around 3300. I doubt that with the little throttle I had left that it would have got up to 4600.

If you can't get to 4600 rpm, then you are overloading your engine, all the time.
Overloading means it's got too much strain on it for constant running.
Your mechanic is correct, you should be seeing in the 4600 rpm range if you want your engine to last.

 

[Agoose]

Re: Alpha One upgrade with 454 ?

I tried a 15 pitch aluminum and it took longer to plane off and the top end was 32 mph.
Any suggestions on where to go with the prop.?

 

[Don S]

Re: Alpha One upgrade with 454 ?

After that, you need to post your question in the Prop forum, you will probably get better answers there.

Here's a quick link to the prop forum:

forums.iboats.com/bbBoard.cgi?a=viewforum;fid=40