4.3L Alpha 1 I/O rpm/speed

[prc03sx195]

I don't have owners manual so need to konw what the recommended rpm vs speed is for this boat. 19.0 ft glastron. Not sure I am getting proper setup with it. Thanks

paul

 

[Silvertip]

Re: 4.3L Alpha 1 I/O rpm/speed

So what are you observing now at wide open throttle? Speed is what you get when the engine is at or near the top end of the recommended rpm band which in your case is in the 4600 - 4800 range.

 

[prc03sx195]

Re: 4.3L Alpha 1 I/O rpm/speed

Wide open is at 4000 rpm but speed is not registering on my speedo. Trying to fix. Last year it was showing 50 mph. I just got a new prop with 23P and 14.0 dia.
Maybe a lower pitch huh?

paul

 

[Silvertip]

Re: 4.3L Alpha 1 I/O rpm/speed

Yes 4000 is low and you are lugging the engine but then we have no idea what engine and drive you have. However, if the engine is in need of a serious tune up or is otherwise not making full power for whatever reason, changing props is not the first thing that one should be thinking about.

 

[prc03sx195]

Re: 4.3L Alpha 1 I/O rpm/speed

Silvertip, it is a 4.3L 195 hp Mercruiser outdrive. The engine is in good tune and only has 54 hrs on it. Thanks

paul

 

[Tail_Gunner]

Re: 4.3L Alpha 1 I/O rpm/speed

Silvertip, it is a 4.3L 195 hp Mercruiser outdrive. The engine is in good tune and only has 54 hrs on it. Thanks

paul

What year is the boat...........I believe you might also verify your tach accuracy if you can...now if you cant id say a 19-20 pitch alum is a lot for that boat..maybe a 21..But that is a total shot in the dark.. Ohh what type of drive aka merc or volvo and gearing would be nice?

 

[codertimt]

Re: 4.3L Alpha 1 I/O rpm/speed

From your userid I'm guessing we're talking about an '03 Glastron SX 195 and as you've stated a few times it has the 4.3 and Mercruiser Alpha 1. The gear ratio will be 1.81:1. It's actually 190HP...

As stated above, 4000 rpm is on the low side. I would expect that is fairly accurate for a 23" prop though. I have a GT 185 with is actually a 17 footer and thus a much smaller boat than yours...and it just manages to turn a 23" prop in the proper rpm range(~4600) with a normal load.

I would think you would at least need to drop to a 21"....and if that 4000 rpm is with the boat lightly loaded, even down to a 19". Once it's all said and done I would expect speeds in the low to mid 40s. That's alot of boat being pushed by a 4.3..