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Collection, Preservation and Display of Old Lawn Mowers

Long Shot but I am trying

Hi all at the Old Mower Club.

I have recently joined because I know all you guys and gals have massive knowledge of mowers, mower engines and the like and I am in need of some help as I seem to have come to a brick wall in a quest I am currently on.

The short story is we inherited an oldish mower (I have summised it was built in 1974, not as old as a lot of your machies I bet!).

Anyway, it seems to be somewhat of a hybrid as it has a Mountfield body, an Atco blade system and Tecumseh engine!

Now, the body is Ok, still in good order, the blades (attached by bolts to each end of the cross arm-it's a rotary mower) were a bit difficult to find but I located 2 on e-bay of all places (triangular in shape with a cutting edge on each side) I managed to get the old, very battered, blades off and fit the new ones and used last year with no real problem.

The problem I have is with the engine. I said it is a Tecumseh but it is actually made as a joint venture between them and Fiat. It's called a Tecnamotor and was built, as I say around 1974.

Now all would be well if I could find out what model engine it is but there are no distinguishing marks on it, some places seem to have been defaced by a chisel! (not sure why). I have looked under every bit of cover, all around the body and under the machine and have drawn a blank every time.

I have looked at the Tecumseh website but this engine is not as current.

The throttle/carburator/govenor linkage is not as I have seen on Youtube video's either. Seems to be a complecated setup.

I stripped it down to clean as it was a mess last winter but, like a fool took no photo's before I de-linked all the bits and cannot now remember how it all fit's together. Not a good position to be in.

To be honest, I don't even know if it was linked properly in the first place but it ran, got a bit hot at times but ran well and steady (until this year). The start of this year it was a real pig to start, kept stopping and just would not get going. I managed to mow 2 square feet!

So. I would like to know if any of you esteemed people can help me. I want to get my machine up and running again so need someone to see if they can help me identify the engine model and tell me how to link the throttle etc again (or properly this time).

I have some photo's on my google drive so if there are any takers I can email the link so you can view.

I really do hope someone out there can get me and my machine going again.

Thanks for reading

John Morris



wristpin Tue, 17/09/2013

Chances are that it's an LAV / LAVR 30,35 or 40 or may be a later version such as  the BV or BVL. The only reason I can think of for obliterating id numbers is that at some time it was stolen but mower thieves don't usually bother as most model and serial numbers on mass produced engines are only specific to the day of production and not to individual engines. Post the links to your images and I will see what I can come up with.

As the id numbers are defaced and from your description it is a "bitsa" what is it that suggests 1974?

hortimech Wed, 18/09/2013

As I seem to remember, technamotor didn't exist until the late 70s - early 80s, so it cannot be a 1974 engine, but no one can begin to try and identify the mower without at least one picture, so post your link to the pictures and let us try.


janbo Wed, 18/09/2013

After reading your story ,think you looked at the wrong places. The indentification numbers are not under the cap but  in the cap . They are in the cooling air duct just above the spark plug. Hope this helps. 

Johnone Wed, 18/09/2013

In reply to by wristpin

Hi Wristpin. Many thanks for the reply.

Please find the link to my G-Drive here:…

The reason I came up with 1974 is that is the date embossed on the underside of the fuel tank, slotted on the back of the engine.

Hope the drive link works OK and I hope you can help in some way.

The main thing, as I said in my speel is to ID the engine so I can get some gaskets for it and link the throttle,carb.govenor arm correctly.

I read some stuff on these types of engines after posting yesterday evening and I have to add that when idling, it revved up and down, not steady as I have heard other machines do, is this normal?

Thanks for now


John Morris

Johnone Wed, 18/09/2013

In reply to by janbo

Hello Janbo.

Thanks for the reply and you taking the time to read my speel.

Here is a link to my G-Drive so you can see what I'm talking about.…


I have seen on a Tecumseh video (Youtube) that the serial number is under the cover, above the spark plug, on the engine. Looking at it I think part of this is missing as the bit that should have the details on is not there. I looked at this some time ago and drew a blank.

Anyway, take a look at the pic's and see if you can add anything to my original question.

If you need more pic's I'll have to take at the weekend and post to the same drive folder.

Thanks for now


John Morris

Johnone Wed, 18/09/2013

In reply to by hortimech

Hello Hortimech.

Many thanks for your reply.

having read what you wroye I am now confused. The reason I said it was built around 1974 was this is the date on the underside of the fuel tank, secred to the back of the engine.

Anyway, please find a link to my photos here:…

If you need more with a wider view I'll have to do at the weekend and post to the same g-drive folder.

See what you can come up with.

Thanks for now


John Morris

wristpin Wed, 18/09/2013

In reply to by Johnone

Interesting! I'm wondering just how much mixing and matching has gone on other than the immediately obvious but I think that it's an Lav/Lavr40. My guess is that your fuel tank is plastic and "clips" to the back of the engine cowling with two built in lugs sliding into cutouts in the cowling. They were prone to cracking and leaking around the lugs so your tank could well be a replacement so I would not put to much reliance on the date molded into it as being relevant to the machine.

Aspera/Tecnamotor/Tecumseh engines of that era often had all their ID data on a metal tag held on by one of the valve chest screws  - not a permanent fixture to link it to the engine!

The colour of the engine cowling and your description of the bar blade with bolt on sections say Atco - probably a green and cream 4-wheeled push machine. This machine existed in several forms, both 2 and 4-stroke, dating right back to the early 50s

The oval (ovoid?) air cleaner suggest  probably earlier than 1974 as does the shape of the exhaust. 

The interesting feature is that "dog leg" governor link and despite thinking that that your engine is "pre Tecnamotor" the only illustration that I can find  is in a Tecnamotor manual so it shows that age and the passage of time can play tricks!

Your uneven engine revs may be as a result of incorrect governor adjustment but more likely down to fuel/carburettor contamination by dirt or gumming from "stale" fuel.

I will scan and post some info on the governor/throttle linkage set up which may help you to reassemble it correctly.

Understanding the principle of its operation is useful in determining what is what.  As the engine revs the internal  governor, via the  arm which is connected to the shaft that comes from inside the crankcase, is connected to the throttle spindle and tries to close it. This closing force is counteracted by pull of the governor spring which is connected to the throttle cable via the the throttle lever mounted above the carburettor.(don't confuse with the one on the handlebar end of the cable!)  These two opposing forces, when in equilibrium, give the governed speed.   Also connected to that lever is another link going to the choke spindle which, when moved past the full throttle position, will close the choke for cold starting.

wristpin Thu, 19/09/2013

In reply to by wristpin

Page E9 Fig 21 shows your "dog leg" governor link

Going back to your original post that the engine is a pig to start.  Aspera/Tecnamotor lumps were never known for their easy starting but in fairness a lot of this was down to lack of proper operator maintenance and servicing.

To get one to start easily everything needs to be spot on. I take it that yours is pre electronic ignition (not to be confused with electric/ key starting!)  - the ignition contact breaker points need to be spot on. The valves need to be seating properly and the clearances properly adjusted - beware of adjusting these with the valves still "on cam" or you will end up with even harder starting and a sprained wrist! The choke needs to be closing fully - linkage adjustment . No air leaks in the induction tract - if you note  the carburettor is hung on the side of the engine on a longish manifold  and was prone to working loose where the manifold joined the block. People were then apt to over tightening this joint resulting in damage to the thick gasket and a warped manifold flange that would suck air (and dirt) until refaced and refitted properly. Later engines had a support bracket for the carb. Finally the cylinder heads were prone to warping resulting in gasket failure. Warped heads can be refaced on a surface plate or bit of thick plate glass and should be refitted with a new gasket and correctly torqued.

To sum up, they were never as resilient to operator neglect as a Briggs and Stratton despite have pressure lubrication as opposed to Briggs's splash system and earned themselves a bad reputation with users. That said, if properly maintained and serviced they were OK - sort of!!


wristpin Thu, 19/09/2013

In reply to by wristpin

Just realised that my later Dropbox pdf post answers the age question! The "dog leg" governor link is stated to be "pre 1967" and that was certainly pre Tecnamotor however that still raises the question as to why that blower housing / engine shroud has Tecnamotor on the decal!  All interesting but totally irrelevant to getting your engine running!!

janbo Thu, 19/09/2013

In reply to by Johnone

Hello , If it is a Technamotor the numbers are in the rectangular section in the cooling duct just above the spark plug and the 3 bolts . It looks like a Aspera engine , and that makes it a different story.  Wristpin gave you a lot of very useful information regarding servicing these engines. Have nothing to add .


hortimech Thu, 19/09/2013

Hmm, interesting machine, a Mountfield M4 chassis and the remains of an 18" Atco rotary combined into one machine. Engine is an Aspera LAV35 and probably it and the machine it was originally fitted to have been through a Atco service centre. Atco used to fully overhaul everything and the machines were returned looking like new, hence the totally incorrect decal on the airshroud.

there should be two links,  the one shown in picture 5 connects the governor lever to the throttle on the carb, the other link, which is straight with a spring, connects the govenor lever to the throttle link shown in picture 3 (the other end to the throttle cable)



Johnone Thu, 19/09/2013

In reply to by wristpin

Hello Wristpin. Well, after reading your information (twice) all I can think of, in the first instance, is WOW!

To be honest, I have no idea of the journey this engine has taken before I got to use it. It seems a mish mash of different era's??!!

Anyway, to go through some of the bits you wrote about, the connection of the manifild to the block side was good, until I took it off to see if the inside was clean or not. I now need a new gasket and also gaskets between the carb and manifold.

I took the head off and the valves looked seated correctly, though there was a lot of carbon deposited on the head. The piston look OK, no damage. I am going to have to read your advice a few times to get my head around all the adjustments you write of. Then take it slowly to re build bit by bit.

I need a new head gasket as well, I would guess, now I stripped the head off. The old gasket looks good but no use now I've sprung it from it's bed. I have no idea of the torque settings for the head bolts, the screws that hold the manifold to the block, if they are needed to be tightened to a specific setting.

The air filter has a new sponge in it and the oil has been changed (the drain plug is underneath like a car, I read most mowers use the same place to empty and fill!)

Anyway, Wristpin, I'll take all your information and diagrams and get to work. There is only 1 place in the UK that I can get parts from for Tecumseh engines so I'll speak with them, armed with your advice as to the model, to get what I need.

Many, Many thanks for your help.

I'm really glad I joined the Old Lawnmower Club.


John Morris.

Johnone Thu, 19/09/2013

In reply to by janbo

Thanks, Jan, for  your input. I appreciate your taking the time to reply to me. Yes, I believe I have all the detail I need now to get my mower working again. It really is a bit of a mishmash though, the linkage being pre 1967!

Anyway, powered with my new knowledge, I'm going to get to work and set it up to run  like a dream!

Thanks again


John Morris

Johnone Thu, 19/09/2013

In reply to by hortimech

Thanks Hortimech, for your information.

I appreciate you taking the time to look into this for me.

Armed with your input and that of the rest of you who have replied I can now get to work and re build this machine.

Looking at one of the diagrams, I have realised one spring is missing so I'll have to try and get one made (like finding a needle in a haystack!)

Wish me luck.

Thanks again


John Morris

hortimech Fri, 20/09/2013

What ever you do, DO NOT undo the drainplug under the engine, if this is undone, they had a nasty habit of coming undone in use and allowing all the oil to leak out, just tip the engine on its side then undo the filler plug.


wristpin Fri, 20/09/2013

In reply to by Johnone

Here is a table of torque values for the LAV family of engines.

Valves - your comments about looking at the valves is OK as far as it goes but it is the valve face and seat that need to be good and you will be hard pressed to inspect these properly without removing the valves. My experience with those old Aspera/Tecnamotor/Tecumseh engines was that they nearly always benefited from a  "valve job" and as a result could be returned to their owners as "first pull starters" - all important when taking money for a job. I would say that as you have the head off , it should be done.

If I read your text correctly you are saying that you think that you are short of a governor spring. Your setup with the dog leg link only uses one and in one of your images you appear to have it. What does appear to be missing (well at least not showing in an image) is the link that goes from the trottle lever to the choke spindle. May be you just didn't include it in the images that you posted.

I have sent you a pm about gaskets - I may be able to assist with those.

Johnone Sat, 21/09/2013

In reply to by wristpin

Thanks again, Wristpin.

Your comments are almost spot on, as you have been before, IE, your question about the fuel tank and how it's mounted a couple of posts back, you were right as the tank has 2 lugs which clip into slots in the cowling, you are almost certainly right about it being replaced as well, as I said in my last post, I have no idea of the journey this machine has taken before falling in my lap.

Anyway, the spring. You are correct, as shown in my photo's, there is a spring but it looks a bit battered and I wondered if it was one which had been put on to replace a broken one in the past. I would guess there should be some stipulation on the tension this spring should exert on the govenor arm? I will put it together and see if it works.

I believe the only bit I have missing is the connecting rod between the choke and the control arm. This is item 'D' in the diagram you sent me over. I have no clue as to where this went to. I still have the spring, part 'W' in the diagram. I almost thrwe this away because I could not work out if it was broken or indeed needed but I see now how it fits so I'll replace to its proper home.

The valves. Where or how can I have a 'valve job' done as you advise would be needed? My mechanic, who does the car, may not be able to do such a thing but I suppose I could ask, unless you have other advice?

Anyway, I'll take a look at your PM and see what you say about the gaskets.

Thanks again (so much)


John Morris.


hortimech Sat, 21/09/2013

In reply to by Johnone

based on what you have done so far, you or your mechanic should be able to regrind the valves.

Easiest way will be to remove the engine from the chassis ( it is only held on by three bolts) and stand it on a bench with the head area upright. Remove the carb assy from the block, on the side of the block is the valve cover/breather, this is held on with two screws, remove these screws and then the cover. You will now be able to see the lower end of the valves, to remove the valves you need to lever up the springs with a couple of screwdrivers and then depending just how old your engine is, either pull out the pin or lever the cap sideways so that it drops down (the hole in the cap is slotted and bigger at one end). The valves will now pull out for examination, the sealing area should be flat all round without any badly burnt patches etc. To regrind the valves, you require grinding paste and a grinding tool ( this is just a wooden dowel with a rubber sucker on the end) both of these should be available at a car accessory shop. Start with coarse paste and spin the valve on its seat backwards & forwards by rubbing the dowel between the flat of your hands. Once you have a clear grey band all way round the valve, clean off the remaining paste and then repeat with fine paste. You will probably have to reset the valve tappets, this is done by removing metal from the valve end, but be careful not to remove too much, the tappet settings are 6 thou inlet, 10 thou exhaust.

If you are struggling to locate a new head gasket, then providing it is a metal one and undamaged, you will probably get away with re-using the old one.