Messing about with Mercos'

[jeff2wings]

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.

[jeff2wings]

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

[jeff2wings]

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 ) it's cosmetically rough ,but if it runs I will tart it up a bit

[jeff2wings]

Well,she's a runner !

will strip and clean up

[jeff2wings]

Another quick rebuild,this one is a 29

[Richard Acland]

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 too]

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

[jeff2wings]

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 !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

[jeff2wings]

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

holds about 3-4 oz of fuel

[jeff2wings]

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

[ken anderson.]

well done again Jeff,wonderfull skills. Could I ask you what do you use to get the ali crankcases looking so shiny and clean please?

ken anderson...ne...1..skills dept.

[Wilco Wingco]

I have just bought a Ben Buckle Super Scorpion with a Merco 35 in it. It still has the long reach idle bar plug that glows a treat. It seems to have a twin needle carb but my other 35, in a BB Super 60, has the air bleed carb?. When did Merco introduce the twin needle carb?. The air frame is date 2005 and is in pristine condition as is the engine. It was built I understand by and engineer. Covered in nylon and doped. Can't wait to get it in the air, once the wind drops to a reasonable level??.

[Rich Griff]

Very interesting, and they can be made to run on petrol !

 

I will be asking lots of questions later on that.

 

I have a few mercos, the marine 61 being well and tuelly stuck after about a 22 year rest.

 

I removed it from the boat and stripped it down with no real dramas using a cheapo carb cleaner which worked well.

 

The c/case minus crank is soaking in brake fluid which seems to be doing its stuff with the solidified dark brown castor.

 

Will try and add some pictures tomorrow.

 

Will be researching new bearings and possibly a gudgeon pin with buttons.

 

The piston has a ring that freed off in the bore no problem, but not cleaned yet.

 

The Conrod looks bent but since my " first incident" ( long story, thought I was going blind, they discovered diabetes, it's in the family on mums side ) everything appears a little "odd", so will make those measuring rods seen earlier in this thread.

 

Interestingly, the piston is not pegged, so ring can rotate if it wants....

 

Must search out the instructions that came with the engine and boat.

 

Will check sizes of the other mercos I have which are all free but would benefit from a clean.

 

Enough for today....

[Rich Griff]

These are 2 of the 3 mercos I have, which when the new fuel and after run oil has arrived ( £105 delivered but will last me 2 years I hope ) and Thier turn comes, will be stripped, cleaned, tank run and afterrun lubed, then refitted to the gyro and a model made for the smaller one.

 

Gyro is a 35 and the smaller one a 29, which may have been a marine version initially, some research needed on that. I have a lathe so could make a a finned air-cooled "sleeve" as the oe find have been machined off.

 

Don't know if this is how a marine version is modified from an aero version.

 

The parts/installation sheet for the 61, which is still being cleaned.

 

Need to research new main bearings, gudgeon pin with buttons and possibly a piston ring.

 

Will be researching/asking advise about the 61 to make it run on petrol...

Edited May 19, 2021 by Rich Griff

[Rich Griff]

Help....

 

Meths is better than brake fluid and petrol at removing gunked up castor goooooo.

 

Jeff2wings, would you remember or happen to know the main bearing numbers/sizes for this engine please.

 

It is a single glow plug head with no "raised" portion of the head sealing area, a non pegged single piston ring, not a "dykes" type. Deflector piston type, gudgeon pin rides on bronze looking piston surface bushes and con rod bushed both ends, big end having a lube "slit" rather than hole.

 

The rear bearing is larger than the front having 8 balls, with a crank diameter of 1/2 inch.

 

Width is close to 1/4 inch using Vernier depth function, but outer race diameter is a questimate of 1inch 3/16 ( 30mm ?). My Vernier jaws will not reach what little diameter there is deep down inside the engine.

 

Front bearing has 7 balls, int dia on crank nose being 5/16, race ext diameter questimate 7/8 and width guestimate 5/16.

 

The merco info sheet says ba threads used so dimensions in imperial rather than metric ?

 

I have been in contact with model fixings....no definate answer yet.

 

I do not want to remove the bearings unless I have new ones in my hand.

 

All help greatly appreciated.

 

rich

[Rich Griff]

Ps, the cylinder head and rear cover has X head screws rather than slotted machine screws, so may be a later engine and metric, but the flywheel nut as information marking ( 88888 sideways ).

 

It cannot be younger than 1990, don't know when they stopped making them or remember exactly I acquired the boat ( wood huntsman ) with the engine fitted.

 

It was a runner and ran well, in fresh water not sea.

Edited May 19, 2021 by Rich Griff

[Rich Griff]

Had reply from model fixings, data to digest and re measure....

[Rich Griff]

61 rear bearing out no dramas, hit oil and momentum method, dropped out first strike...

 

29 cylinder out, dip in hot oil, grip and rotate and it's out...

 

Stuck carb, dip in hot oil, grip servo arm and rotate, it's now free...

 

Hot oil to soften castor goooooo and varnish...

 

Will post pictures after dinner...

 

Good productive day and dry, it's blowing a gale with horizontal rain here, again !

[jeff2wings]

Well l have finally got the Merco sparky installed in the rebuilt powerhouse, just need to remember where I left the servo tray(with servos!) so I can finish it. 

[Richard Acland]

On 30/01/2018 at 01:40, SIMON CRAGG said:

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 REME based in BAOR  in the 70s and 80s. I had a pal who was involved with the target drones. I was a Member of the Wildenrath club and had two models, strangely they were both powered by Merco engines.

[SIMON CRAGG]

18 hours ago, Richard Acland said:

I was REME based in BAOR  in the 70s and 80s. I had a pal who was involved with the target drones. I was a Member of the Wildenrath club and had two models, strangely they were both powered by Merco engines.

Me to Richard. Royal Engineers from 67 - 93. Strange how we ended up with these engines!.

 

[jeff2wings]

I have finished the last two 61 rebuilds,just a couple of 29's left

[jeff2wings]

So getting fedup with building models and not being able to fly them various resons ,thought I may as well mess around with a couple of mercos, the Mk III just needing a set of cylinder screws made,shouldn't take long....................

 

.........5 hours later 😕 just need to make 9 more short ones for three sets hope it doesn't take another 5 hours 😅 

 

This Mk IV will be made up from leftover spares, I will be boring out the case to take a larger late model crankshaft 

 

 

[Nightflyer]

I have had mixed feelings about Merco's since start of model flying in the mid 70s. So at the time a number of members in my local club had Merci powered cl and rc models. I had  Merco 35 Black Streak which was notorious unreliable runner and no was not set up as it was looked at by everyone. However it eventually led to loss of a model which put me off the engine. It was not until a couple of  years later that a change of carburettor actually sorted the engine out. 

[Michael Denest]

I have this Merco muffler I would like to use on a Merco .49.  Not being able to find information on how to set up this muffler, can any of you provide suggestions?  As assembled, it looks to be a sealed chamber when clamped together, restricting exhaust gas flow.  What would be the purpose of the exhaust tube?  Is the rib in each muffler half ground away and the tube provides the sound reduction?