Johnson 1980-1984 35HP vs 1987 30HP

[Jim Hawkins]

I'm looking at a motor tomorrow. A early 80's 35HP Johnson.(I don't know exact year yet)
I currently have a 1987 30HP Johnson.

I am wondering about the difference in the 2 motors. Correct/Inform me please.

I believe both are 31.8 Cubic Inches (as is the 25HP I think)
I read that in the early 80's the gear ratio was changed.
I read that they changed the way they measured HP in the early 80's

So to the point, do these 2 motors deliver the same HP or is the 35 the stronger motor?

Thanks

 

[Jim Hawkins]

Re: Johnson 1980-1984 35HP vs 1987 30HP

After more searching it appears the 25, 30 and 35HP all have the same displacement, bore and stroke so the question,

Is there a difference between the late 80's 30HP and the early 80's 35HP or did the HP rating change in 1985 because of a change in the way they measured it?

More info,
Up until 1983 they offered a 25HP and a 35HP
In 1984 They had 25hp, 30HP and 35HP
Then in 1985 on they only had 25HP and 30HP

 

[Jim Hawkins]

Re: Johnson 1980-1984 35HP vs 1987 30HP

Continuing my research I think the only difference between a 1984 30HP and 35HP is going to be the gear ratio.

Using this page
By the Numbers: Gear Ratio Determination and Speed Calculations for Your Boat | Evinrude Nation Community
it appears my motor is 2.25:1 or .44 with 12-27 gears.

So I guess I'll need to check gear ratio on the 35?
Any advice yet?

 

[Jim Hawkins]

Re: Johnson 1980-1984 35HP vs 1987 30HP

OK, once more,

Looking at part numbers for the gears in a 1984 30 and 35 HP motor the numbers are the same, and to make it worse, so are the carbs.

I'm stumped.

 

[jasper60103]

Re: Johnson 1980-1984 35HP vs 1987 30HP

OK, once more,

Looking at part numbers for the gears in a 1984 30 and 35 HP motor the numbers are the same, and to make it worse, so are the carbs.

I'm stumped.

Jim,
looks like you determined there's no difference in horse power, only the way they measured it.
The only other change that comes to mind is they went from a choke system to a primer.

How did the new motor check out?
jasper

 

[Jim Hawkins]

Re: Johnson 1980-1984 35HP vs 1987 30HP

How did the new motor check out?
jasper

I didn't go. Decided I did not need another motor identical to mine but older.

The thing that gets me is that year 1984 where they had all 3 models,25, 30 and 35HP. I think probably there are really only 2 different motors, the 30/35 HP and the detuned 25. Maybe they were midyear when they changed the HP rating accounting for the same motor being classed differently. Maybe the website where I checked motors and parts is wrong. Maybe it's a conspiracy, I don't know and I'm thinkin I don't care anymore.

I know that my 30HP has the same Displacement, Bore, Stroke, Carb and Gears as the 35HP so what could there be to gain?

maybe I'll go tomorrow

 

[skurven]

There is one more difference, its vital. You still interessted?

 

[jimmbo]

He hasn't cared for four years....

 

[GA_Boater]

There is one more difference, its vital. You still interessted?

LOL It's only been a couple of months since Mr. Hawkins has been in the forum, but still, LOL

Closed