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Messing about with Mercos'

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jeff2wings19/08/2018 18:54:43
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796 forum posts
1891 photos

Well Percy,that depends on the kind of spares you need ! If like every one else back in the day,you used castor fuel the engines will be in good condition under all the crud,however,50% of the 49&61's I've brought the bearings have been toast from the congealed castor.I have used Model fixings for replacement bearings for the Mercos and other engine projects,not the cheapest but they more often than not arrive the next day yes .Things like piston rings can be had from gaviscool on e-bay,and I make gaskets from thick brown parcel wrapping ,as for any thing else,I make !

Frank,as Percy says,however,that said,if it's a small case mk II from '66 on, the carb choke was smaller so suction would be fine,should make for a nice retro combination with the astro hog.Try and get a P&R strap on silencer,I may have one going spare in my box of bits !

SR71 ,the 29&35's come up on e-bay ,sometimes for little money you can of course convert an r/c to stunt by locking the throttle open or fit a stunt venturi.

some more pics of the 35imga0277.jpg

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Percy Verance19/08/2018 21:16:24
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8108 forum posts
155 photos

Well Jeff, I don't need any spares just now, but if I were to begin flying my Mercos once more then I probably might need spares at some point. The last spare I needed was a crankshaft for my .49, which got bent in the resulting crash following a mid-air in 1984.........and of course they were readily available back then.

Edited By Percy Verance on 19/08/2018 21:17:02

jeff2wings03/09/2018 22:20:05
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796 forum posts
1891 photos

Just a few more finished engines....................

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and this is one of my Ltd 'Black edition' 49 Mk 1 made from leftover bits !

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next will be a Mk 111 and another bitza

jeff2wings11/09/2018 21:38:19
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796 forum posts
1891 photos

Well this is the last of the Merco restorations ,I still have plenty of others to build/restore that will be in my other thread,I may even build a (retro)model or two for them! dont know

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Mk III with micro-flow carb bit of a rarity (for a merco that is lol !)

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MkII with Enya carb from the bits box

Frank Skilbeck11/09/2018 22:22:30
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4500 forum posts
101 photos

Jeff, the Mk111 with micro-flow is what I've got. I tried running it but was getting a very severe leak from the cylinder head joint, took the head off and there is no gasket, so it looks like I will have to address that.

jeff2wings12/09/2018 07:28:46
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796 forum posts
1891 photos

Frank,mercos never had head gaskets the head sits directly on the liner,I would suggest you try lapping them together,if that dose not work I will look in my spares box ,might have a twin plug ?

Frank Skilbeck12/09/2018 08:15:17
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4500 forum posts
101 photos

Jeff, thanks, I will investigate further. The engine has been cleaned up by a previous owner so I will have a look at the head/cylinder joint to see if there is any problem there.

It looks like it has newish head screws, 3 short and 3 long, just wondering if these might be slightly too long and are bottoming out, do you know what length they should be.

ken anderson.12/09/2018 14:30:19
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8454 forum posts
773 photos

hello Jeff,

I admire your work on the engines....well done

ken anderson...ne..1.... admiration dept.

jeff2wings12/09/2018 22:29:19
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796 forum posts
1891 photos

Thanks Ken,it' a bit like restoring a car or motorcycle,but quicker and not so expensive (as I keep telling the wife!)

Frank,short screws are 3/8 long(threaded part) and are 1/8 whit ,have found the test report by Peter Chinn in the Sept '68 RM and no head gasket,however looking at the pictures it looks like the cylinder head has been machined to leave a band around the combustion chamber,my guess to size would be 1 1/8 o/d x.020-30 thou high .The head on my Mk III is also flat but I think at some point in the last 50 (!!) years it's been ' got at' as it had a non-Merco con rod in it so may not be the original head?

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as received,no gap at head

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you may just be able to see the raised band on the head

Edited By jeff2wings on 12/09/2018 22:31:10

jeff2wings13/09/2018 20:45:35
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796 forum posts
1891 photos

So had a go at a spare head on the lathe

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std head just visible witness mark from liner

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30 thou step

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smaller contact area will give better seal

jeff2wings16/09/2018 18:36:54
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796 forum posts
1891 photos

So popped the head off my Mk III for closer inspection and it looks like the Mk III's heads are different to all other merco heads,there is a 10 thou step(not 30 like I made) the Mk II was a bit of a odd one out to previous and following engines.

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jeff2wings10/08/2019 21:37:18
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796 forum posts
1891 photos

Well not quite done with Mercos yet, just got a 50 and this, a late 61

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This is the last of the line,larger 15 mm crankshaft with bigger gas passage,ABC liner with more port area and new style carb

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jeff2wings16/08/2019 20:58:53
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796 forum posts
1891 photos

So I thought I should bring this project over to this thread as it's merco based

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std crankshaft modified by blanking off the inlet and slightly relieved to help with lubrication

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drive pin from silver steel

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bronze thrust washer

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ready to run (once I've made some more screws laugh) it's cosmetically rough ,but if it runs I will tart it up a bit

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jeff2wings17/08/2019 19:05:14
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796 forum posts
1891 photos

Well,she's a runner !smileyyes

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will strip and clean up

jeff2wings21/09/2019 22:13:48
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796 forum posts
1891 photos

Another quick rebuild,this one is a 29

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Richard Acland22/09/2019 16:04:43
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51 forum posts
28 photos
Posted by SIMON CRAGG on 30/01/2018 01:40:00:

The Army used to have a team called the "MATS(A) team that flew Merco .61 powered models as targets on range days. Everything from small arms to main armament was usually fired at them. They were given a transit (ish) vehicle and filled it with engines (no exhausts), 13x6 blue plastic props, hundreds of idle bar glow plugs, VERY heavy models with a parachute built in to the cockpit, Skyleader radio gear (nice push/pull servos), fuel (straight + petrol mix!), plus all the other gubbins to support them. There were several teams. They travelled the World!. Even flying from ships when we had a navy. How do I know all this? I used to organise range days in BAOR many moons ago, and as a keen modeller the swaps and bartering that could be done would make your eyes water!.

I was stationed in BAOR in the 80s and belonged to both Wildenrath and Gutersloh model clubs I was in the Army and had a contact that was involved with the target drones.Funnily enough my models were powered by Merco engines.

Rich too22/09/2019 19:35:15
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3053 forum posts
1070 photos

Fantastic work Jeff yes How many refurbed motors do you have, and do you always run them when finished ?

jeff2wings22/09/2019 20:20:13
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796 forum posts
1891 photos

TBH I've not had the nerve to count them all,but I must have about 30 ish mercos and the there are all the other makes +diesels blush!I don't always run them up after being restored if I have two of that model,one for show ,one for go as they say .

So got the Merco RRV finished as well as the MDS

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