Electric Choke Operation

[buddyearl]

I have a question on how the electric choke operates on my '66 80hp Starflite. There are 3 options choke on, automatic, and choke off. Which one should it be in to use the electric choke? I've had it in the automatic position but on a cold engine the butterflies are closed so pushing the electric choke doesn't seem to do much. I appreciate any help.

 

[Chris1956]

Are you sure you have an electric choke on that model? I have seen the "Automatic" setting on hot water and hot air actuated chokes. These chokes were similar to 60s and early 70s auto chokes, except the OB version can rust up....

 

[andreipou]

I was going to put the same question when I saw this thread.
I have the 1968 40 HP Evinrude.
3 choke position on engine: ON, OFF, AUTOMATIC.
When ON - fly is closed, when OFF - fly is open. No questions here.

But, when AUTOMATIC - fly is closed too.
My understanding that on AUTO it has to be open and when I push CHOKE button on dash it has to close because solenoid (that is bran new and works) will pull metal rod inside and pull fly to close position.

I made picture of choke solenoid vacume assembly with cover removed and cover with spring picture too.

Buddyearl, is yours the same?

If you imagine how spring hooked end positioned when cover is closed, you will see that spring will push fly lever clockwise (the same direction the solenoid would pull when I push button) , but this will keep fly close all the time.

My understanding is that spring has to pull lever counterclockwise keeping fly open and solenoid will pull it clockwise when power applied and close fly.

I can not fugure out how to hook it for that unless some part(s) is missing.

Any idea?

I have original repair manual, but it is not covered in it....

Thanks.

 

[racerone]

When motor has started hot air is drawn thruogh a heat exchanger and over the bi-metallic spring to control tension on the " fly " ---The hot air comes through that metal tube !!

 

[F_R]

That "spring" is a thermostatic device ("bi-metal). It expands when heated. At room temperature, the choke plates will be lightly closed by the bi-metal spring. When you activate the solenoid, it pulls the plates closed tighter for a cold start. Once started, the bi-metal spring holds them partially closed to provide partial choking till it warms up enough to run without choking. Hot air is pulled through the steel pipe leading to a heat exchanger located behind the exhaust cover (hot exhaust blows on it to heat it). That hot air is what heats the bi-metal spring.

Lever must be in automatic position for all this to happen.

BTW, sometimes some well meaning person that doesn't know any better will plug the air inlet to the heat exchanger, obstructing the air flow to the choke. Needless to say it won't heat up under that circumstance.

Also, a rotted/rusted out heat tube or heat exchanger won't get it either. In fact a rotted heat exchanger will blow exhaust gasses to the carburetor/intake manifold.

 

[racerone]

I just chuckle when I see one of those air intakes plugged.

 

[andreipou]

This is the part I am having troubles with:

". At room temperature, the choke plates will be lightly closed by the bi-metal spring. "


It is just closed as buddyearl mentioned too.

I will try to play with it more and see.

But the hook on spring goes UNDER the lever (closing the fly),right? ?

 

[F_R]

Yes, the bimetal closes the choke. It is adjustable by rotating the spring/cover. Adjust it to lightly close the choke at room temp. You can tweak if from there if you experience over or under warm-up choking.

 

[andreipou]

This helps a lot. I will get some time on Sunday to play with it and see...
Thanks.

 

[buddyearl]

Mine looks like yours Andreipou. I put it in the auto position. The butterfly valves are closed on a cold engine but open slightly while cranking. When I push the choke switch it will hold the valves closed or fully choked. On my engine it doesn't need much choke to start. Once it starts I let go of the choke switch. The valves open up quickly once spring gets heated. I have my cover bi-metal spring adjusted lean or just tight enough to hold the valves shut when engine is cold.