33hp Johnson vs 25 hp

[jkb52088]

I have done multiple searches and haven't found anything on this. My boat is rated for 25 hp motor. But I need to know. I've talked to several people and they are not familiar with the 33 hp motor. Is this basically a 25 hp motor with the high end of the performance rating printed on the motor, or is this as larger, heavier motor that exceeds the limits of my boat. I don't have to, nor plan to run wide open. I'm new to boating, and I and trying to decide if I should get this motor I'm looking at on craigslist. I got a week before I get to look at it as the owner is out of town, so I'm just trying to find out something before I get something I shouldn't. Any help is appreciated.

 

[hardwater fisherman]

I dont know which year 33hp you are talking about but in1968 they where around 140 to 150 lbs. Again I dont know which 25 you are talking about but I would think that it would be around 100 lbs. I think the 33 was more like a derated 35 or 40hp. Anyway you are exceeding max hp by 8hp or 30 percent.

 

[racerone]

The 33 hp started out as a 28 hp in 1962 then became 33 hp in 1965 till 1970.---------------------A very good motor that uses the same crankshaft / connecting rods as a 40 hp of the same era.------------This is a much debated subject but a newer 3 cylinder 25 weighed in at over 150 lbs and likely is the same power as the older 33 hp motor.

 

[steelespike]

25s before 1977 were 22 cubes after were 31.8 cubes, the 33 is 40.5 cubes.
closely related to the 40 which is 43.9 cubes
The 22 cube 25 is under 100 lbs the 33 is probably at least 120 lbs. as is the later 25 heavier than the early model.
The 33 is rated at 4500 rpm the 69-76 25 is rated as high as 6000 rpm.
The early 25 might actually be faster than the 33 if it can reach 6000 with enough pitch.
I think it is obvious the 33 will do better with a load.
You need to stick with a motor fit for your boat.
The later 25, 31.8 cubes will have more guts than the early model It has a max rpm of 5500.

 

[racerone]

The 3 cylinder 2 stroke OMC 25 /35 are in the order of 150 lbs.--propshaft hp.-----The 33 is lighter but not propshaft hp.-----A newer 4 stroke 25 hp is likely heavier than the 33 hp.-------The point is the rating of boats has changed very little , but the motors available today has sure changed !!!

 

[jkb52088]

Here lies the problem, the first person states the obvious: the motor is too big. Then the next three responses comparing size and rpm. I have an 07 alumacraft 1448. So to me its max motor rating of 25hp is a newer 4 stroke 25 hp motor. If the older 33 is similar in size and rpm, wouldn't that technically be within the newer ratings. I will push this boat to its load limit during duck season at times, but most of the time it'll be just be me and my wife well within the limits. I just don't want to end up with something that won't work, either too small to push during hunting or too big due to ratings. It also doesn't help that I will end up will a deal if it all works out like I'm hoping.

 

[racerone]

The 33 hp is an excellent / simple / cheap to own motor.

 

[steelespike]

A 25 Merc 4 stroke is 172 lbs the 33 is about 120.The 33 is rated at the crank so less than 33 my guess is 30-31.
Lets use the 30 hp number that is 20% higher than the boats rating.Seems significant to me.
The Merc 30 is the same as the 25 so your saying its ok to put it on if your were doing a new motor.
It appears you are fitting the boat to your motor not the motor to your needs.
I feel the 33 will use more fuel than say a 25 or 30 from the late 70s to early 80s.
Obviously it won't break you but it will be significant.

 

[hardwater fisherman]

According to the outboard manufactures page here at Iboats in 1968 the short shaft 33hp was 140 lbs. And the long shaft was 144 lbs.

 

[jimmbo]

The 33hp(4500 RPM) is the same powerhead that was used in the 1957 - 1959 35hp. It was previously mentioned that it was based on the 28hp powerhead. Not so, the 28 hp was based on the 1956 30hp(4500 RPM) engine which was a hopped up 1955 and earlier 25hp(4000 rpm). The 22 cu in 25hp was a hopped up 18/20 hp engine, it was rated at 5500 rpm vs. the 18/20 at 4500. On a very light boat it was a screamer, but it lacked torque so it wasn't the best choice for a heavier boat. In the late 70s a new 25hp based on the 32 cu inch block was a detuned 35 hp of the same size

 

[roscoe]

Personally, I like electronic ignition.
And its nice to be able to find someone that can AND WILL service your motor if needed.

So I would choose a newer motor, maybe from the early 80's.

And make sure you are buying a motor that matches the transom height of your boat, or you will be asking for issues.

As far as hp and weight; is it legal in your state, to hang a 33 hp motor on a boat rated for 25 hp ?
It is clearly not legal in my state (Wisconsin).