compatibility

[waltwager]

would the carburetor from a 1976 25hp Evinrude be compatible with a 1978 25 hp Johnson?

 

[flyingscott]

would the carburetor from a 1976 25hp Evinrude be compatible with a 1978 25 hp Johnson?

Different block sizes. One is 22 cubes the other is 32 cid

 

[waltwager]

Thanks. I don't know why 1978 Johnson put the lowspeed control where you can't get at it while running unless you have the cover off. Seems like backward engineering since it was so accessible on the 1976 Evinrude

 

[flyingscott]

It is because the newer block is a much more forgiving on setting the low speed. The 78 should pretty much be a set it and forget it. If you have to keep adjusting it you either have something wrong or just can't keep your hands off the adjustment.

 

[waltwager]

Thanks again. Actually the motor runs pretty well at low speed, and If I gently move it up to higher speed it goes up and runs okay, If I move it up rapidly it bogs down and will stall. Most likely fuel pump?
However, when running at a higher speed on a plane, it vibrates a lot - I'm going to try a different prop, but other suggestions might help.

 

[racerone]

The general buying public buys new " nice , neat looking stuff "----Showrooms are full of this stuff.----People who buy this stuff used say " why did they make repairs so difficult "-----Or ----" Why is it so difficult to make this simple adjustment "

 

[waltwager]

Actually I enjoy making old engines run again. The only downside is I don't have all the special tools to remove and replace seals. I hope to learn something with each repair and it sure helps to communicate with others who have already been there - done that.

 

[racerone]

Myself I look at a say a 1963 model 10 HP Johnson / Evinrude.---You see a " big looking " motor that weighs around 64 lbs.------I say wonderful design and when cover is off you can see lots off empty space.--- You can easily get at all the thing on it.-----Reed valves / recoil etc.------On a modern " compact looking " motor when you take the cover off you can not get your fingers in there to repair / inspect anything.

 

[jimmbo]

------On a modern " compact looking " motor when you take the cover off you can not get your fingers in there to repair / inspect anything.

Same goes for todays cars. You have to pull the engine to replace a Thermostat, or Heater Fan

 

[Dave1027]

Thanks again. Actually the motor runs pretty well at low speed, and If I gently move it up to higher speed it goes up and runs okay, If I move it up rapidly it bogs down and will stall. Most likely fuel pump?
However, when running at a higher speed on a plane, it vibrates a lot - I'm going to try a different prop, but other suggestions might help.

Bog when you nail it usually indicates the low speed/idle mixture is set too lean. Try opening it a 1/4 turn.

 

[jimmbo]

Or a messed up carb-timing sync

 

[waltwager]

The only carb sync timing adjustment I see is the cam follower to the marks on the flywheel. Am I missing something?

 

[racerone]

There should be no reason to replace a carburetor.-----Unless it has been molested.-----What trouble shooting has been done.-----Gear oil checked ?------Prop shaft possibly bent ?

 

[waltwager]

I asked because I have a 1956 25 HP Evenrude that runs great so I thought if they were compatible I’d swap them out to see if the carb needed attention.

 

[racerone]

A 56 carburetor ???---And a 1956 model 25 HP ?-----I thought the 56 was a 30 HP motor.-----Post #1 mentions 76 and 78 motors ?

 

[waltwager]

Sorry, 25 hp 1976 evenrude
25 hp 1978 Johnson.
Don’t know where 1956 came from (brain fart)