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Messing about with Mercos'

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jeff2wings19/08/2018 18:54:43
809 forum posts
1989 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



Former Member19/08/2018 21:16:24

[This posting has been removed]

jeff2wings03/09/2018 22:20:05
809 forum posts
1989 photos

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




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



next will be a Mk 111 and another bitza

jeff2wings11/09/2018 21:38:19
809 forum posts
1989 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


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



MkII with Enya carb from the bits box

Frank Skilbeck11/09/2018 22:22:30
4814 forum posts
107 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
809 forum posts
1989 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
4814 forum posts
107 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
8753 forum posts
810 photos

hello Jeff,

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

ken admiration dept.

jeff2wings12/09/2018 22:29:19
809 forum posts
1989 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?

s-l1600 (8).jpg

as received,no gap at head

merco 61 mk iii page 1.jpg

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
809 forum posts
1989 photos

So had a go at a spare head on the lathe


std head just visible witness mark from liner


30 thou step


smaller contact area will give better seal

jeff2wings16/09/2018 18:36:54
809 forum posts
1989 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.


jeff2wings10/08/2019 21:37:18
809 forum posts
1989 photos

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


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


jeff2wings16/08/2019 20:58:53
809 forum posts
1989 photos

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


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


drive pin from silver steel


bronze thrust washer


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



jeff2wings17/08/2019 19:05:14
809 forum posts
1989 photos

Well,she's a runner !smileyyes


will strip and clean up

jeff2wings21/09/2019 22:13:48
809 forum posts
1989 photos

Another quick rebuild,this one is a 29

s-l500 (1)merco29.jpg


Richard Acland22/09/2019 16:04:43
131 forum posts
70 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
3060 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
809 forum posts
1989 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




jeff2wings07/12/2019 21:54:32
809 forum posts
1989 photos

Today I made the fuel tank for the Merco sparky that will go in my Powerhouse


holds about 3-4 oz of fuel


jeff2wings07/02/2020 20:26:07
809 forum posts
1989 photos

So here's my latest Merco project,it's a bit of a Frankenstein job using a scrap engine case used as a proof of concept from my RV build and left over bits from the Meteor RV build.


the case was scrap due to a spun front bearing and all the screw threads being striped out,all holes drilled out and filled with alloy solder.


as was the mounting holes


the Meteor crankshaft has a bigger crankpin than the Merco so a new rod (and piston) made to fit


here are the components from both engines


completed engine



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