Johnson 40ES70A Choke spring position

m1dn

Seaman Apprentice
Joined
Sep 16, 2020
Messages
39
Hey folks,

Was wondering if someone can help me with the automatic choke on the 1970 40hp engine with hot air choke.
I can't figure out what should be position of the choke spring on the starboard side.

There's On, Automatic and Off choke positions.
The spring was disconnected initally so Choke/Lever was always closed aka On, as a result engine flooded and died pretty much right away.

Cleaned the carb, tuned engine etc and well since Valve remained fully shut, it couldn't properly start.
I tried "logically" putting spring into the hole on the lever to hold the valve Open ( choke off ) on Automatic position and engine ran like a butterfly.

However, i didn't fully screw in the choke lever thinking it should be able to move for Automatic choke and with engine rattling or maybe automatic working? it shut's it down and starts feeling pretty bad.

I heard "Automatic" choke on those engines was pretty bad even on new ones, so my question would be what's the best way to avoid it as in what position should i keep my choke lever and how tight it should be?
If it set it to Off, would i have to manually On it every time to start or the primer on console would be still helpful in this case?

Attaching pics of the lever, spring and other side with air intake
 

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racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,047
Off----Choke is off.----On ---Choke is fully on.-------In automatic position there should be slight tension on that spring.----That tension is adjusted by rotating the cover on the other side.----The bi-metallic spring under that cover responds to temperature as warm / hot air is drawn into carburetor via that steel tube.--- The tube comes off the heat exchanger in the exhaust manifold.------The solenoid is activated for cold starting.----These used to work very , very well when properly adjusted.----Have not worked on one in many years now.-----Have many of these on parts motors today.
 

m1dn

Seaman Apprentice
Joined
Sep 16, 2020
Messages
39
Off----Choke is off.----On ---Choke is fully on.-------In automatic position there should be slight tension on that spring.----That tension is adjusted by rotating the cover on the other side.----The bi-metallic spring under that cover responds to temperature as warm / hot air is drawn into carburetor via that steel tube.--- The tube comes off the heat exchanger in the exhaust manifold.------The solenoid is activated for cold starting.----These used to work very , very well when properly adjusted.----Have not worked on one in many years now.-----Have many of these on parts motors today.

Thank you! That was it pretty much, port side was unscrewed too much and moved with engine rattle and starboard side cover was screwed in too much so the on auto position the valve was hard-shut at all times.
Set the cover to barely tension it to have valve in open position, going to do a good cleanup and test-run tonight in garage.
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,047
You will need to test run with water in a bucket 6 to 8" above the impeller.----Tradition muffs do not work well on this motor.----Main water intake is behind the propeller.
 

m1dn

Seaman Apprentice
Joined
Sep 16, 2020
Messages
39
You will need to test run with water in a bucket 6 to 8" above the impeller.----Tradition muffs do not work well on this motor.----Main water intake is behind the propeller.

Thanks for guidance!

Update: engine runs like a charm now.
I've set the cap/spring to full open with a slight tension.
Choke button on dashboard now closes it as expected and engine runs like a butterfly ( one VERY VERY loud butterfly ).
Poor neighbors.

Will do a full lake test later in the week, once the throttle cable arrives
 
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