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Messing about with Mercos'


jeff2wings
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Interesting Mercos? This is a petrol conversion from 'back in the day' - although when that would have been I have no idea. I have been around modelling since about 1972 and I have a very vague recollection of Dunham Engineering adverts in the mags. It has a very crude set of external points attached to the front and I believe it to be unrun (No surprise there!)

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A friend bought one of the Merco petrols when they were on sale IIRC about 25 or so years ago. I remember going with him back to the shop where he bought it and he said something like "after forty years of running model engines, this so and so has defeated me". The chap in the shop said "I'm not surprised" and gave him a full refund!
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Some interesting replies ! I vaguely remember Skyleader running an add with those target drones,think one of the mags did a feature on it ?? you can tell an "MOD" spec merco as they had no drilling for a silencer and a bit less well finished on the out side.

Stu,Dunham eng. used to make rep engines ,such as the Orwick 64,Hornet 60 ,1/2 size DC Wildcat etc .Nice MERCO btw (better on glow though )

Here's Mercos factory effort

s-l1600.jpg

It's on e-bay at the mo (not mine btw) nice compact ignition unit (not laugh) !

TM after years of faffing about with different boil n' bake methods,I got a blasting unit

img_20180318_135118.jpg

before

img_20180319_204126.jpg

and after ,one on left is unused.

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So the next one for rebuild will need a bit more work as at some time in it's life it's been face planted into mother earth with the result that it has a bent shaft and conrod sad Well a few deft blows with a (soft face) hammer sorted out the crank,but the conrod needed a bit more finesse !

img_20180318_104748.jpg

yep,that's had a thump !

img_20180324_170132.jpg

made some close fitting gauge pins,it looks worse than it is,very carefully bent straight.After that just a simple re-assemble

img_20180325_175909.jpg

img_20180325_175852.jpg

img_20180325_175900.jpg

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  • 4 months later...

Well,I think I must have merco-itus or something ,just got four more projects !

s-l1600.jpg

This looks like it's never run but has been left in a damp shed,will need new bearings most likely.Mk iv early '80's

s-l1600 (1).jpg

and just for a change,a 35&40.......and a twin plug 61 from mid late 70's

s-l1600 (3)0.jpg

this will need a bit of work...

and it's not just mercos' that I mess about with.........

 

Edited By jeff2wings on 12/08/2018 14:12:52

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I've acquired a Merco 61 twin plug, quite clean, good compression and turns over smooth, tempted to put it in a Flair Astro Hog, hopefully would be a good combination. Just got to sort out a silencer as it came with a small home made exhaust defector. Would it be best to use exhaust pressure for the tank or not?

Edited By Frank Skilbeck on 19/08/2018 08:24:51

Edited By Frank Skilbeck on 19/08/2018 08:25:34

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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

imga0276.jpg

imga0274.jpg

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  • 3 weeks later...

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.

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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

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