Suffolk colt carb settings

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ex-towerman
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Suffolk colt carb settings

Hi, my name is Terry,  I am a new member and very keen to learn about taking apart and renovating petrol mowers. 

I've managed to acquire 4 Suffolk mowers up to now, I've stripped down one Suffolk colt model 3a, replaced piston rings, bearings, new muffler,  cleaned out the carb, and to my utter amazement it actually fired up.

Great I thought,  but no, it ran for a while and now it will start but only run for a few seconds and dies, I've tried setting the carb to the correct settings (or so I think), is there anything that I am doing wrong. 

I must say that I am not a mechanic or any sort of engineer,  I was a crane driver for over 40 years so maybe my username should be clueless!

So if any of you knowledgable guys could help me to get  the old colt running nicely again I would be very grateful,  thank you. 

DJD
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Welcome to the club, did you

Welcome to the club, did you remove and clean what I call the 'emulsion tube'? It's a piece of brass about an inch and a quarter long, it sits in the outer periphery of the lower ally casting but only a tiny part sticks up, gentle persuasion generally gets them out, not grabbing by pliers and force! Main jet needs to be about one turn out approx. to get started up. Is inlet jet blocked up?  Are you sure that the spark is good?

 

ex-towerman
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Good morning DJD, thanks for

Good morning DJD, thanks for your response to my question about the carb settings.

Well no, I didn't even know that there was such a thing as an "emulsion tube" (but I do now), I think the best thing for me to do is to take the carb off again and check  everything and make sure I carefully remove and clean the "emulsion tube" .

As for the spark, that's pretty good, but I will check the points again and the plug gap.

Is the points setting .020?

As you have probably gathered from my posts, I know absolutely nothing about mower engines, but I'm more than willing to learn and take advice.

Many thanks DJD.

Kind regards,

Terry.

 

 

 

 

 

 

 

 

hillsider
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https://www.oldlawnmowerclub

https://www.oldlawnmowerclub.co.uk/sites/default/files/opmanual/Suffolk%...
 

Follow the above link and you should find a copy of the Suffolk Colt handbook around page 8 you will find some setting information and cross sectional drawings of the carb and it's component parts. Do remember that the carb settings given are usually base settings that will allow the engine to run and may need to be adjusted a little to achieve sweet running.

Good luck. 

ex-towerman
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Thank you for that link

Thank you for that link Hillsider, very informative and it will be my go-to for this and many others that I hope to (try) breath life back into.

I'm enjoying the challenge even though it's a bit frustrating at times, but I intend to keep doing it until I get it right.

Thank you.

Terry.

wristpin
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Well no, I didn't even know

Well no, I didn't even know that there was such a thing as an "emulsion tube" (but I do now), I think the best thing for me to do is to take the carb off again and check  everything and make sure I carefully remove and clean the "emulsion tube" .

Emulsion tubes are found in many carburettors but not in the Zenith as used in Suffolks. In the Zenith in question it is - and described as such in the parts diagrams - the slow running tube. It draws fuel from the base of the float chamber , connects to the top section of the carb where that fuel is mixed with air in a little chamber under the slow running adjuster screw. From there the slow running mixture passes through a minute hole into the back of the inlet manifold and thence into the engine.

An emulsion tube is usually found in the centre stack of the carb and has cross drillings as well as the centre one to allow air to mix with fuel forming an air/fuel emulsion - hence the name- that then enters the main air flow in the Venturi

On the the early Zeniths the slow running tube is screwed in , indicated by a slot in its head. In later  carbs the tubes are a push fit and frequently well stuck in the float chamber casting . Warming up with a hot air gun or even boiling it up in a pan of water on the stove will sometimes free it off .  If it’s really stubborn, and to avoid crushing it , enter a small close fitting twist drill or panel pin, such as the ones from a certain brand of picture hanging hook , into its top. The tube can then be gripped with pliers without fear of crushing it. At the other end of the tube there is a minute hole which may be cleaned by inserting just one bristle of an old style wooden handled wire brush  - no need to remove the bristle from the brush!!

ex-towerman
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Thanks Wristpin, I had

Thanks Wristpin, I had already

taken the carb off and tried to remove the little tube in question with just my fingers, and not pliers like DJD said, but I could not shift it.

I'm off up to Inverurie tomorrow to spend a bit of time with my son and his family, but when I get back I will be trying some of the things you have suggested to remove that pesky little tube (carefully).

When I've worked out how to get photos onto this page I hope you all would not mind seeing a before and after of what I have achieved so far.

Thank you Wristpin.

Regards.

Terry.

Ian H
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Running for a few seconds and

Running for a few seconds and dying sounds more like the classic fuel starvation issue. I would disconnect the fuel line at the carburettor end and put it in a jam jar or other suitable container, and open the fuel tap on the tank.  There should be plenty of flow.  If not then the fuel tank and and any filter could need a good clean.  On the early Suffolk carburettors the fuel line is connected to a banjo fitting with a gauze inside. This could also be blocked so worth undoing it and checking and cleaning that too. Once you have established good flow, only then is it worth trying to diagnose any carb issues if that has not fixed it.

Hayters gonna Hayte.