1956 30hp Johnson

30hpbob

Seaman Apprentice
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Aug 23, 2011
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34
My motor started and ran after installing new coils, condensers and points. However it run pretty rough at low and high speed, no so much at high speed. Also wondering how to adjust the low/high speed "lean/rich" settings. Thanks for any help you can give me.
 

BonairII

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Jun 7, 2011
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2,727
Re: 1956 30hp Johnson

Basic start settings are 1 1/2 turns out for low speed needle(final adjustment when motor is warmed up). Make very small adjustments(giving a few seconds for motor to respond to each adjustment).
Turning needle in 'leans' the mix.....out 'richens' the mix


High speed needle is around 1 turn out(varies from motor to motor). Final adjustment needs to be done on the water at WOT

A service manual will give you exact directions.
 

30hpbob

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Aug 23, 2011
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Re: 1956 30hp Johnson

Thanks Bonair. Do you think that it running rough is part of the low/high speed settings. I was wondering if the timing could be off.
 

lindy46

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Nov 27, 2008
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3,886
Re: 1956 30hp Johnson

Did you remove the core plug on the top of the carb and clean the idle circuit beneath it?
 

30hpbob

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Aug 23, 2011
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34
Re: 1956 30hp Johnson

No. Did not even know about the core plug or the idle circuit. First I will reset my plugs at .30 instead of .20 and see if that makes a difference with engine running rough, if not I will take a look at that idle circuit. Thanks for the help.
 

kfa4303

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Sep 17, 2010
Messages
6,094
Re: 1956 30hp Johnson

yup. Points at .020, with Champion J8C plugs at .030. New 7mm copper core spark plug wires would be a good idea too. You'll be amazed at what a difference they can make. If the welch plug is stubborn, you can remove it by twisting in a screw a few turns and giving it a tug.
 

lindy46

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Nov 27, 2008
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3,886
Re: 1956 30hp Johnson

J8C is a little hot unless you're trolling all the time. I'd use the J6C for best overall performance.
 
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