INFO Question

[dw2000ta]

I have (what I'm Told) a 1992 Glassmaster 22' with (had) a 4.3 v6 and mercruiser alpha one. now I know that glassmaster doesnt exist anymore and was sold to bentley and duracraft. I'm doin a restore and wanted to put a V8 383 in it. however, I cant find any information on this boat as fas as hull specs or HP Limits. If anyone has any info on this boat that would be great. I'm replacing everything from the stringers up. (in the process of deconstruction) Was also wondering.. if no info was available on the boat. Would I have to replace the transom to handle the power of a V8. How much HP can the Alpha one handle. What was the stock prop size and specs? Would a thicker transom require a longer shaft for proper alignment?(if possible?)

Thanks for any info and answers.. It is very much appreciated as this is my first restore.

 

[NYBo]

Re: INFO Question

I believe the Alpha 1 is good to 300 HP. However, the gearing may be wrong for a V8.

Boats that size don't usually have HP ratings.

The transom doesn't bear the brunt of the power, the stringers, via the motor mounts, do.

 

[HT32BSX115]

Re: INFO Question

I believe the Alpha 1 is good to 300 HP. However, the gearing may be wrong for a V8.

Boats that size don't usually have HP ratings.

The transom doesn't bear the brunt of the power, the stringers, via the motor mounts, do.

Howdy,


I had a 66 Marktwain 18' boat that my dad bought new. It was available with Mercruiser engines ranging from the 4cyl 120 + MC-#1 drive up to and including the 310HP 409V-8 + the MC-#2 drive.

The max HP on the HULL placard was 310HP.

Most all boats that size would be just fine with what you want to do.

As for transom thickness, Do not exceed the max thickness specified for Mercruiser drives. (They have a range of thickness)

The Alpha 1 is good for 300 PROP-shaft HP. That'll mean the engine will be doing around 330 crankshaft HP. If you keep the RPM under 5000 RPM, you'll probably not exceed that unless you spend FAR MORE money on the engine than most of us would want to afford!

That's a pretty good size boat. Find yourself a Bravo III and you'll be amazed at how well it hole-shots!

I removed a 340hp OMC 460 from my 1987 21' Four Winns Liberator several years ago and replaced it with a 330 HP 454 and Bravo III
While it's a few MPH slower at the top end, it is a literal ROCKET out of the hole!!


Cheers,


Rick

 

[dw2000ta]

Re: INFO Question

this is part of my dilema.. this glassmaster doesnt have a readable badge or sticker anywhere. so knowing the hull rating is my issue. the bravo III sounds awesome but with an almost $7k price tag thats more than I'm willing to put into this boat for just a prop. Any other suggestions to mate with a Chevy V8. Hopefully pushing for right at 400 Prop HP. I can check local and surrounding boat yards for a different setups with reasonable prices..Just unsure of whats good and whats bad...Brand wise

 

[HT32BSX115]

Re: INFO Question

Hopefully pushing for right at 400 Prop HP.

That means a crank shaft HP of around 450hp.......... not going to happen with an SBC that you turn onder 5000 RPM unless you spend more than the boat is worth and/or put a supercharger on it.

If you do it, you'll break an Alpha in short order.

btw, in 2005 I paid $5000 for a complete 454 + Bravo gimbal and Bravo III as removed from a 1998 24ft Bayliner

 

[dw2000ta]

Re: INFO Question

so is 5000rpm a deadline or something...i mean seriously. or is that the safe rpm to run.. Ive built 3 other 383 motors. with different combinations heads,cams,and exhaust. ofcoarse not boat motors.. I know for a fact that i can make 400 hp on a 350 with a cam alone. then again i really havent gotten into marine engines before. still learning so everything i gain here is sure helpful.

 

[Fishermark]

Re: INFO Question

The 5000 rpm limit is due to the outdrive. You need to plan your engine to create its torque and HP in the lower rom bands. Much different than a car engine. Do a lot of reading before you go out and spend a lot of money.

 

[HT32BSX115]

Re: INFO Question

I know for a fact that i can make 400 hp on a 350 with a cam alone.

It might be fine in boat with drystacks...... until you "kill" the drive.....

That engine in a "wet" exhaust marine installation will probably not survive very long. Reversion will damage it in short order.

There are a LOT of people that run Alphas above 5000 RPM. A seriously "built" Alpha with a drive shower might last a while but I wouldn't do it in a boat I was going to use for tubing and skiing.


I think Mercury put the Alpha behind the 454 for about a year before they came out with the Bravo. Nowadays, they limit the Prop HP to 300hp with the Alpha......(about 330 crankshaft HP)