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1955 Evinrude carb build

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Randy Hogan

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Anyone out there point me to a manual or online instruction to carb rebuild on 1955 7.5 Fleetwin 7518. My first time on forum so stumbling through getting info path down smooth. Thanks
 
The carburetor itself is a model of simplicity... nothing like a automobile carburetor. The only thing to adjust is the float and the needle valves (explained below).

However... do take some pictures and make notes "before" removing the carburetor as you might not remember just which way that cotter pin went or how that spring hooked up etc etc.
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(Carburetor Float Setting)
(J. Reeves)

With the carburetor body held upside down, the float being viewed from the side, adjust the float so that the free end of the float (the end opposite the hinge pin) is ever so slightly higher (just ever so slightly off level) than the other end. And when viewed from the end, make sure it is not cocked.
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(Carburetor Adjustments - Two Adjustable N/Vs)
(J. Reeves)

Initial settings are: Bottom high speed = seat gently, then open 1 turn out. Top slow speed = seat gently, then open 1-1/2 turns.

Setting the high and low needle valves properly:

NOTE: For engines that DO NOT have a shift selection, obviously there is no NEUTRAL position. Simply lower the rpms to the lowest setting to obtain the low speed needle valve adjustment.

(High Speed) Start engine (it will run pretty rough), shift into forward gear, take up to full throttle. In segments of 1/8 turn, waiting for the engine to respond between turns, start turning in the bottom high speed needle valve. You'll reach a point whereas the engine will either start to die out or spit back (sounds like a mild backfire). At that point, back out the needle valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest setting.

(Low Speed) Slow the engine down to where it just stays running. Shift into neutral. Again in segments of 1/8 turns, start to turn the top needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running. Eventually you'll hit the point where the engine wants to die out or it will spit back. Again, at that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustments, you will have no reason `to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.
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One more thing...............
The brass cam that slides against the throttle lever of the carburetor. Usually there is a scribe mark on that cam... and the throttle butterfly should just start to open when that mark is dead center with the lever... BUT I can't remember if that's true with the 1955 model 7.5hp Evinrude or not,

If not, I'm sure another member will forward the proper adjustment to make on that item.
 
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Thanks that will come in handy once I get to that stage. What I was hoping to find was a service manual or instructions on the rebuild itself. Somewhere I've read them. I think there are several different unique things to do that aren't normal steps with this carb. I can probably make my way through it. You are right it is a simple carb mechanically.
 
Carb build went about as easy as could be. Thanks. Now that's done moving on to impeller replacement. Ouch. More than I thought it would be having to remove powerhead. Reading on line seems doable. Any advice or veteran tricks to make sure it goes easy? While I have everything apart is there anything else to do while inside?
 
joereeves said:
I can't think of anything to add... looks like you're on your way.
Click to expand...

All went as described in removing powerhead to access water pump. Now waiting on gasket to complete reassembly. Then points condenser tune up and should be ready attempt cranking. Being a car buff and this being my first shot at boat engine, This engine really is about as simple a machine as I've seen. Ashamed modern technology has over complicated many aspects of mechanics
 
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