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Collection, Preservation and Display of Old Lawn Mowers

My First Official Atco Project

I will use the thread to log and track the process of my full restoration of my Atco 20".

The mower was purchase in Germany and had been stored outside under plastic for many years.

The exact date of the mower is still not known, currently somewhere between 58 and 62.

This thread will be pic heavy and all help, tips and support will be greatly appreciated.

This is how it looked when I got it home after a 8 hour round trip.

The question of preservation over restoration didn't really cross my mind, or I'll rephrase that. It did cross my mind until I got in home and saw the state of it. I might keep the grass box as is. Or at the very least leave it until the mower is finished before contemplating what to do with it. 



Newdur Sat, 19/03/2016

Striped off the tank and bars

Took the bars and cross braces to work and shot blasted them. 

Left the tank as is until I come up with a plan of action on stripping it and cleaning it out.

I then wiped them down with nitro and primed them 

wristpin Sat, 19/03/2016

That's a nice machine and looks in good order for its age, find a spark and it could go to work!

You can see the damage to the chain case resulting from the slack intermediate chain. If you look at the inboard end of the shaft that the intermediate sprocket sits on I think that  there's a large nut ** which if slackened allows the sprocket to move in a slot and, depending on the age of the machine,  the shaft itself may rotate  "elliptically" so that both chains may be adjusted together but independently  - if that makes sense?!. From memory the early machines did not have the elliptical rotation so getting the tension correct on both chains was a bit of a compromise.

** 7/16 BSW I think..or  7/8 ish / 21mm ish  across the flats !

I wonder at what stage its front rollers were discarded? As far as I know those high cut wheels were always an accessory and not an alternative option to the conventional rollers.

wristpin Sat, 19/03/2016

Re internal cleaning of the tank, one option for rust removal is electrolysis . Plenty of info on the web but here's a couple of recent images of a tank in process.

Newdur Sun, 20/03/2016

I've taken the casters and the mountings off and it looks like they are factory fitted. I see no signs of any other mounting or bolts ever being attached. The paint is in first class condition.

In The F10 parts manual it looks to me like it's was delivered, either or. It very frustrating not knowing the build year or having the exact paperwork to go with it.

Latest development regarding dating, I removed the flywheel yesterday and uncovered some stamp markings. One on its own 59 and a 63 and a 66 amongst a group of other numbers. Any ideas or am I look for something hat isn't there.

i can't believe it's 1966 but it's not a bad year for a machine living in Germany. The 59 is hand stamped by the looks of it 

gtc Sun, 20/03/2016

As mentioned elsewhere, Sir Chook is the go-to man for Atco information.

I have a 14 inch Atco 4 stroke, year unknown. I'm not into 4 strokes myself, but I had to take this one as a condition for getting 2 stroke Atco bits. When I asked about it elsewhere Sir Chook replied: "The engine is a Villiers Mk 7 it has a 50mm bore and a 38mm stroke. They are rated at about 1.3bhp. These engines were fitted to 14, 17 and 20" (domestic) mowers. The heavy duty 20" machines were fitted with Villiers Mk 12 or Villiers 730E engines."       (Domestic = Oz in this instance)

Suggest measuring the bore and stroke of your engine as a means towards engine model identification/confirmation.


wristpin Sun, 20/03/2016

We fitted a few high cut kits to later heavy duty Atcos and they picked up on the same bolt holes etc as were vacated by the standard  height adjusters and rollers which would account for there being no apparent  modifications.

Possibly  your best source of dating information for the magneto / engine would be Paul Child  at  

Newdur Sun, 20/03/2016

Thanks GTC Ive been in contact with sirchook and he is as stump as me, it's clear it's a MK12 what's not clear is its date... He has sent me a few manuals and adverts from the time but still can't pin down a date.

Hi wristpin, that's what I mean. As they use the same holes I would have expected to one of two things, if not both.

1. Discoulararion or textre difference in the paint I der the bracket. This would be where the gap in the roller mount where the height adjustments were made. If to roller was on few a few seasons.

2. Some slight scratching under the mounting bracket where the roller height had been changed

Neither of the above are visible so I would presume it was either factory supplied or more likely change at the very beginning. Does that make sense??

gtc Sun, 20/03/2016

Anything of possible use here? :

Atco 20" , 20" 'Special' , 24" , Late 1950s-Early 1960s ; Villiers
Atco 14" (B13) , 17" (D7) , 20" (F12) , Late 1950s ; Villiers
Atco 20" (SF9) & 24" (SH4) Sidewheel Motor Mowers , Late 1950s ; Villiers
Atco 20" (F10) , 24" (H5) , Early 1960s ; Villiers
Atco 20" (F16 & F22) , 24" (H8) , Early 1960s ; Villiers

wristpin Sun, 20/03/2016

Take your point but looking at your parts break downs they seem to confirm that the fixing bolts are the same for both applications and are "stationary" in the chassis  - (square under the head engaging a square hole in the chassis? ) and the area that would mark is on the (missing) roller adjustment quadrant.

We need someone who was there at the time!

I'm done!

Newdur Sun, 20/03/2016

Hi Gtc, I've got all of the, relating to a machine with casters, sir cook was very forthcoming and wrist pin sent me the F10.

The F10 seems the most likely candidate, apart from the differences in the grass box. But as wrist pin mentioned this could of been a replacement box. This would then put the machine around 58-60. The only thing I would have thought if it was a F10 the brass plate would read F10 20, wouldn't it? Mines 4S 40.

Hi Wristpin, Sorry I wasn't trying to disprove your theory I was only trying to explain what I could see. Thanks for you comments and the F10 parts list its come in extremely useful during the strip down and marking of the parts. 

gtc Mon, 21/03/2016

The only thing I would have thought if it was a F10 the brass plate would read F10 20, wouldn't it? Mines 4S 40.

I'm no expert on those codes, however I guess there is the chance that some of those coded/stamped parts may not be original.

There's also the possibility that "export" mowers had differences. That's often the case here in Oz.

Newdur Fri, 25/03/2016

After a few dozen PMs/emails visits to other forums and a couple of Atco lovers. We have come to the conclusion that this is a 1959 F10 built for the 1960 season. Thanks to all you guys that helped, gtc wristpin, Marc 

Newdur Fri, 25/03/2016

I've had a few days at home and have got most of the mower apart. 

So this is where I'm at at the moment. Wondering what to do fully strip the motor, or give it a good flush and leave it as it is.

ive drained the oil and have had the sump off. In side the block it's looks hardly worn just covered in very thick old oil. 

So the question is

1.if I was to take it apart, what should I soak it in to clean it?

2. I want to take the fly wheel off to clean behind it. Is there a process to this or can I just take it off to clean.

3 the fly wheel is missing some blades, this must have been done when it was previously removed. I may replace it. Does anyone want to part with one?




Newdur Fri, 25/03/2016

You can see that the cut out bushing is missing. According to the parts manual I'm missing Bush, screw insulating , washer insulating , screw cutout terminal. I'm assuming if I insulate a bolt passing through would suffice. Has anyone a pic of how this looks or any idea of sourcing the bushing?

wristpin Fri, 25/03/2016

The  most likely source of Villiers parts are Paul at Meetens , George at Villiers parts, Villiers Services (although more bike than industrial) and Jon at the Hailsham Mower centre.

Would think that you can overcome the switch problem by making an insulating bush / collar with small bore plastic pipe or "casting" one in Araldite or other similar non conducting epoxy. If you have access to a minature lathe you can possibly turn up a bush from Paxolin or similar insulating material.

If you've washed the sump out I would leave the inside of the block alone but when back up and running get the engine good and hot and drain and refill. Avoid flushing oil in an air cooled engine.

The flywheel is "self extracting". Loosen the nut a couple of turns and it goes tight again . Then undo it further and it pulls the flywheel off its taper. Quite a lot of force is needed to pull the flywheel which possibly accounts for the broken fins. Villiers used to supply a "flogging" spanner for the job. A strap wrench or similar will help to hold the flywheel.


However when you do this the ignition timing will be lost and you will have to re-time the engine on reassembley. No big sweat but if its just a question of cleaning and adjusting the points it can be done through one of the flywheel windows.

The image of your flywheel gives the impression that the fins may be a cast alloy ring screwed to the flywheel  - if so one of the above supplier may be able to supply a new or used ring.

Newdur Fri, 25/03/2016

Thanks, I like the idea with the araldite. I have some high temp heat shrink I might give that a go first around a bolt.

one benefit of not striping the block down is the mess it will save me, the only thing is I struggle to see how I get the external oil free and polished. What do you guys useless do, wire brush with spit and polish?

I'm going to have to take the flywheel off to fix the cut out switch, If I mark everything before removing the fly wheel would I still need to redo the timing or would it just be a case of lining everything back up?

wristpin Fri, 25/03/2016

You may find that the flywheel has some timing marks on it relating to Top Dead Centre and the points being set at the recommended gap. Otherwise it is a case of setting the piston at the BTDC position and the flywheel so that its cam just starts to open the points at that position and holding that setting while the nut is firmly tightened.

Not sure what you mean by the "external oil feed" ? Possibly the crankcase breather? If so just unscrew it,dunk it in petrol, blow it dry and refit it.


Newdur Tue, 29/03/2016

So the motor is dismantled and slowly getting wire brushed. The last parts of the frame will get blasted sometime next week.

The block seems to have been at sometime sprayed silver. whats the general consensus on a restoration, spray the block silver/aluminum to match the sump or leave O Natural? 

The other point I'm not sure about is the nuts and bolts on the frame. To spray green or leave natural?

wristpin Tue, 29/03/2016

I believe that the silver finish on the block could be as it left the factory but I think that Atco used to spray the assembled chassis so the hardware would have been green. At some point - and hopefully someone knows when, Atco changed from their original slightly darker/muddier  green to lighter more full bodied green often referred to as New Atco Green. Your machine would, I believe, have been originally finished in the darker colour.

In the 50s and 60s Atco used to offer a full winter overhaul service at their various UK depots, This included a complete mechanical overhaul, paint strip and repaint together with new transfers/decals.…

Newdur Tue, 29/03/2016

Thanks wristpin, it's great to look back to the old marketing material. You must have a small library worth of old mower elated paper :)

I didn't think about spraying it complete, I've always had in my head spraying it by the individual part. To get the off the shelf look individual is the way to go, but I'd then have to mask off the rest to paint the nuts and bolts....:-/

Yes the older muddy green is the one I'm going with I'm just trying to source a supplier over here.

its surprising the amount of primer I've gone through after blasting the frame.

ive already ordered my decals but I'm atleast four to five weeks off finishing.