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The one with the wooden handles does not have a brass plate or any other identifying numbers.

That's a shame Mick, but hopefully we may be able to date it for you...
BTW, my 1451 had the alloy rear rollers as well, and the same small clutch finished in red enamel.

Greetings All,

McDougal - very nice Atcos. I have a few myself. From what I know of the post war Atcos the the oblique finned 79cc engine came into production in 1947. I have a 1947 12" which has the very first series of this engine. The model engine on your machines came into production in 1948 and finished production in 1959/60. The long tubular exhaust was a version of those used on previous models. These exhausts were used up until 1951. In 1951 the first version of the pepper pot exhaust came into production. These exhausts were forward facing (rather than to the side). It appears that in about 1952 the pepper pot exhaust took on its well known orientation.

As far as other changes in the models that help to date the 1950's Atcos there are several. The handles were solid aluminium from 1947 - 1951. In 1952 the handles were hollow aluminium. In 1954 the handles were turned oak. In 1958 they were tubular steel with plastic covers.

The clutches are the small solid steel type from 1947 - 1953 and then the more common plate type from 1954 - 1959/60. The clutches on the 1958 4 stroke machines changed slightly. Some of the final 2 stroke machines had the same clutch as the 4 stroke including the drive dogs.

The fuel tank configuration also changed. The fuel tank was supported by separate supports from 1947 - 1953. From 1954 to 1959 the tank was supported by the main handle bars. However the separate supports were retained on the 20" machines. From 1958 the more squat tank appeared on the four stroke models.

The kick starter on the 1947 model was steel, changing to aluminium in about 1948. The starter dogs were milled steel from 1947-1953 with the best known pressed steel type appearing in 1954. In about 1957 the starter changed again. The rope start appeared in 1954 and was an option on the 14" and 17" models.

The engines remained much the same through out the 1950's however the main difference was on the 20" machine. 1948 - 1953 the 20" used the 78cc oblique finned engine and from 1954 onwards the 98cc engine was used.

As far as I can ascertain the rollers were either aluminium or steel depending on the option chosen, although later models tended to be steel.

Catchers also changed over time with the very first being steel (probably a hang over from the previous model) with the aluminium ones entering into production in 1947. In 1954 the 14" and 17" machines were provided with steel catchers. The 20" machines appear to have remained aluminium the whole way through.

There are other small changes between models including changes to the chain tensioner, bed knife arrangement, minor changes to the clutch and so on.

There is one little trick on machines after 1950 - there is a series of letters and digits on the flywheel under the cover plate, the last two digits are the year. These are the date of the engine rather than the mower but if the flywheel and engine are original it will give you a good idea of when the mower was made. If you couple this information that above, you can get a fairly good idea of when the mower was made.

I hope that these details help others to date their Atcos.

Very Imformative and concise information Sir-chook.I know next to nothing of the Reels as I only restore Rotaries...With one exception,the dating of Villiers engines.But its good to read up on what others like now and again.Im very certain this Info will go a long way in helping memebers.Very impressive Sir,you appear to know your Atcos extremely well.

I'm very impressed, Sir Chook. You have given so much detail, so clearly expressed, that if my memory were a bit better I'd be able to date the 12" I once had fairly precisely. Because it had the long tubular exhaust and solid aluminium handles it was clearly made prior to 1951. It had a small diameter solid steel clutch, but my recollection is it was much shorter than McDougal's small diameter clutch. The catcher was aluminium. It all hangs together except that I've always been rather sure the kickstart was solid steel, which would make it 1947, but I can't recall that with complete certainty. There is one other detail you haven't clarified for me. My crankshaft and flywheel lacked keyways, so timing was a rather awkward process, especially if you didn't know what the breaker gap should be (I didn't). I'm told that all of those two strokes that everyone else remembers, had keyways. Is there a date when the keyway was added?

None of my three have keyways. All are Villiers two strokes.

Thanks Mcdougal. Since we know one of yours is post-1954 (the one with the wooden handles and pepperpot exhaust), obviously the no-keyways situation went on for quite a while. Incidentally I bought my 12" pretty cheaply because the previous tenant had pulled the flywheel, fitted a new moving breaker arm bent at an acute angle to the fixed point so the points couldn't even open, and thrown away the porthole cover for the flywheel. (The flywheel itself was supplied as a loose part.) The buyers weren't exactly lined up and bidding against each other to take on that challenge. It took me something like 2 hours to work out what the breaker gap had to be to ensure the moving magnet was in about the right place, bend the breaker arm so the points met each other square-on, time it to slightly before TDC, and make a porthole cover out of aluminium sheet. I was cursing my purchase decision pretty freely by then.

Hi Sir Chook, thankyou very much for posting this information. This will be invaluable for future reference in our archives.

Greetings all,

I am glad that the information is of use . I have taken a few photos this morning to show some of the differences (and similarities).






The above shows the flywheels from a 1953 and a 1956 78cc engine - both are the same and do not have a keyway. They are timed by lining up the timing mark on the flywheel with the corresponding mark on the engine. Engine is timed at 5/32 before TDC and points are between .012" and .015". The 98cc (Midget) engine from my recollection is the same except points are set between .012" and .016"




The above is my 1247 which shows the clutch, exhaust, carby and starter. The carby is of the earlier kind - from what I can understand the Mk II carby started to appear somewhere around 1949/1950.







The final series of photos shows the differences between the 1452 and 1455/56. The main changes are clutch, fuel tank supports/handle bars, bed knife arrangement, handles and chain tensioner.

My 12" mower did not have any kind of timing mark on the flywheel. It would have been nice to have one. I timed the flywheel by varying the breaker gap until it hurt my fingers a maximum amount when I flicked the flywheel while holding the plug lead. If I recall correctly I couldn't feel any difference between 0.012" and 0.015", so set it somewhere in there. I timed the crankshaft so it was slightly before TDC when the points opened. It didn't kick back at all, so I probably could have advanced it a bit and improved the cold starting. If by 5/32" you mean as measured by piston movement, that may have been about where I ended up.

My mower looked the same as your 47 model except I do not think the end of the exhaust pipe was squeezed flat. (Quite possibly a former owner disliked the squeezing and panel-beat it round, of course). My fuel line did not look like yours - I think it was a clear plastic tube. Sounds as if that may not have been original either. There was some kind of challenge in getting the starting sprocket on the end of the crankshaft to not be touching the kickstart when the engine was running - I didn't want the over-running clutch to be running all the time of course. I seem to remember it was all a matter of taking up the slack in the bolt that acted as the pedal stop, in the right direction and timing the nut so the pedal rested against a flat.

One of the most annoying features of the mower was that at idle, the aluminium catcher resonated, rattling against the mower and making a considerable din. It wasn't nearly as bad when the engine was driving the mower: it 2-stroked nicely if running slightly uphill, and when it wasn't uphill I held it back a bit with the handles to achieve the same result. Also, when warm it started very easily with a quick kick of the pedal. The clutch was horrible: it was in or out, I never managed to get it to engage smoothly, and the mower would tip back onto my hands due to inertia whenever I engaged it.

Thank you for posting those pics and information, it is taking me back a lot of years. It was the first mower I ever owned.