Atco 20" Questions

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Simon
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Atco 20" Questions

Hi everyone,

Moved on from finishing my Colt and bought a 20" Atco. I'm struggling with finding info about the engine though (I don't actually know the model of mower either) but I'd like to check the points, set the spark plug gap etc. Its a Tecumseh engine and I can just about make out SER 9297C on the case. Can someone point me to some information about it?

Another query, I'm trying to get to the points but three bolts are proving extremely difficult to undo - they're absolutely solid. Just want to check I'm not undoing anything I shouldn't be - it's the three to the left on the image below.

Final question, when its time to change the oil, the drain plug looks like it'll make a mess, are they designed to take the engine off to remove the oil? There's a strange pipe on the other side of the engine - could this be used to drain oil? Picture below

Thanks a lot!

Simon

wristpin
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It's a Tecumseh H50 or

It's a Tecumseh H50 or possibly an H60, most likely a 50.

Those three bolts are cylinder head bolts and go down through the head into the block.. They will normally be tight, from memory they were specified to be tightened to 20ft lbs. During the passage of time, they may have corroded where they pass through the head.  If you are concerned about shearing them try just moving one just a fraction and then apply penetrating oil all around the head and leave to soak. I am not a fan of WD 40 and prefer Plus Gas or the old Holts Graphited Penetrating Oil  - if you can find it. If you have access to a gas torch, hotting up each bolt head, in turn, may help.  

The machine itself is a Heavy Duty 20 and a pretty robust bit of kit. Be aware that early machines had BSF and BSW threads and later ones UNF. The engine threads will be UNF, UNC.

The weak point was always the freewheel ratcheting system on the cutting cylinder drive. I am told that new parts are no longer available.

That pipe above the rear roller is the oil drain, specially designed to make a mess. Warm the engine up and tip the machine back before undoing the plug over a suitable container. 

I will post an illustrated parts list later. 

Simon
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Thanks for the detailed reply

Thanks for the detailed reply, very useful. One bolt came off but the others are tighter than I've ever seen - I've had them soaking but I think I might have to try applying some heat. Do you have a manual for the H50 / 60 engine by any chance?

wristpin
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Here is the machine parts
Simon
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Thanks, that'll come in handy

Thanks, that'll come in handy! Had a good clean up, just can't budge two of them three nuts. Had heat, impact driver, mole grips, all sorts but no luck so illI leave that bit.

Its running and sounding pretty good now. Only trouble is once i engage the clutch and start driving its good for around 15 seconds then begins hunting and cuts out. Doesn't seem to struggle or anything just goes lumpy and stops. Starts back up fine and the cycle continues but it'll sit still and run perfectly when stationary.

Any ideas? Its like it doesn't like going over small bumps or something?

wristpin
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Not sure about those symptoms

Not sure about those symptoms. May be a partially blocked main jet. Just getting enough juice until asked for a bit more urge. The carbs on those engines could be a prone to internal blockages that wouldn’t respond to cleaning. Particularly susceptible to water damage. 

Has yours got an adjustable main jet - screwed adjuster through the centre of the carb bowl nut? If so try opening it half a turn. Otherwise a thorough clean with an aerosol carb cleaner or, if you know anyone with an ultra sonic cleaning tank, a good hot session in that .

If no adj jet but just a nut, undo it , remove the carb bowl ( try to keep the O ring gasket in place) and clean out any debris. If the nut has a hollow well , make sure that you clean that out  also.

Simon
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The carb has a jet underneath

The carb has a jet underneath the bowl which goes through the nut. It has the normal tickover one and another just under that but turning it has no effect at all while its running so not sure what that does? I did as you said and opened the underneath one half a turn and it fixed the problem, but when I went to it today it hunted and switched off after around 10 seconds driving (it ticked over fine for a few minutes before)

Took the bowl off and there was a tiny amount of debris, nothing major but I've cleaned it out. The plastic washer around the nut in the bowl isn't in the best condition either so I'll replace that too. Not too sure what else to try really.

wristpin
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Strip the carb and give it a

Strip the carb and give it a thorough clean - its the dirt that you cant see that causes the grief!

Simon
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Definitely better! Its

Definitely better! Its running without cutting out since cleaning the carb again thoroughly. Sounds nice too other than a very slight miss fire now and then. Could you tell me what the jet does which I'm pointing to in this picture please as it doesn't have much effect... 

I'm getting a drip of fuel now from where the air cleaner meets the carb. The float is fine, very free moving and not stuck so not sure why? It only happens after running for 10 minutes or more.

 

Simon
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Kind

Simon
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Just an update, the fuel is

Just an update, the fuel is going through the carb, into the air filter and running out of the actual filter. Its like the carb bowl overflows into the air filter but the floats not stuck or obstructed. Not sure if theres a vacuum or maybe something missing?

wristpin
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The screw  is the slow

The screw is the slow running / idling jet adjustment.

The fuel seepage is most likely a float needle and seat problem.  Ideally you would test it with a small pressure pump but you cold rig a gravity tank with the carb upside down and just the weight of the float resting on the needle and watch for seepage.

If it has a soft tipped needle, try changing it. If it is a one piece hard-nosed needle you will have to change the seat - pull out and press in the new one.

Simon
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The float is like a horseshoe

The float is like a horseshoe shape sat horizontally and hinged at one side. Can't describe it but hopefully you know the sort i mean?

I took the air cleaner off and started it to see what happened, it ran nice for a short time then the tiny outlet I've circled in the picture below began pouring petrol out. It stuttered and stopped then so probably flooded itself.

Does that indicate anutanyt other than the float to you? As it seems fine when i inspect it.

wristpin
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The float could be the

The float could be the culprit but more likely the needle valve or possibly an obstructed float bowl breather. Does it flood when left standing with the fuel turned on?

Simon
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Yes it does, its like it just

Yes it does, its like it just keeps drawing fuel in while the taps on. 

I'll have another look at the float, i don't know what to look for now as its seems free and ok.

wristpin
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If it is flooding while the

If it is flooding while the engine is not running it is not "drawing fuel in". The carburettor is gravity fed so the weight of the fuel in the tank is overcoming the closing force of the needle in the needle valve. So either the float is not applying sufficient pressure onto the needle or the sealing surfaces between the needle and its seat are imperfect. As per my earlier post, it's my guess that it is a needle valve/ seat sealing issue.

Have you tried my suggestion re holding the carb upside down while connected to a fuel source?  If that is satisfactory it is possible that the float is not supplying enough closing force to the needle when in the correct orientation. Remove the float and shake it - can you hear any fuel sloshing about inside it? If so it is leaking. If no sound, take a mug of just boiled water and dunk the float in it, holding it underwater with a suitable instrument and watch for any bubbles. if there are bubbles, the float is leaking.