canadagoose

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Does anyone have any more info on the engine pictured? All i know (not sure if it's completely right) is that it is a Merco 61 two stroke (duh, seeing it says it on the side) that was converted to a 4 stroke around 1980 by a company called Stebro. Does anyone know if that is right and how many were converted, etc. All info appreciated.

Hobbsy

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CG, that is cool, I have the .61 two stroke and several other MERCOS including a black .50, never heard of the 4 stroke though. Thanks for the pic.

TFF

Stebro is also the name of a high end car exaust company making them for Ferraris and such; maybe a spin-off? It is very cool. Does it use the stock piston? Enya or old OS style cam style setup it looks like.

canadagoose

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TTF, i have no idea what it uses for a piston, it does use a cam setup similar to the Enya and OS open rocker engines. This cam box bolts in place of the back plate. I don't have the engine yet but i am curious of a few things too like the cylinder liner

downunder

Very neat, the liner would have to be a new one (can't have those silly ports messing things up ) and I'd suspect they used the original piston but with the baffle machined off. For interest's sake, yours started life as a Mk2 with the twin plug head.

canadagoose

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Thanks downunder for the info that it started as a MK2, i was thinking too that the liner would have to be a new one without ports.

captinjohn

Please post some photos of your converted engine as you take it apart to check things inside. Thanks Capt,n

Kmot

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Question & Answer Answered On
Q: Reggy isn't quite right - the name comes from the company directors R.Stephens and D.Brown, they were based in Luton. These engines run well, I still have mine with the original invoice dated Sept 1982. See review in Model Engine World 7/98. Regards, Peter S Jun-27-09
A: Thanks Peter, Very helpful and interesting. Regards Michael G
Q: Hello, this is a Stebro conversion from the 8O'ies I have one of these, obtained from John Goodall that I finished with a highly polished head and gear housing and copper exhaust. The bro stands for brothers but I forgot tha Ste abreviation. This is NOT 5O or 6O'ies. I will place a bid for a friend collector, I have over a 1000 engines myself....... kind greetings Reggy Jun-22-09
A: Thanks Reggy. Very helpful and interesting. I had never seen one of these before. Regards Michael G

canadagoose

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Hey Kmot, thanks for the bit of info. Where did you get it from? You don't know how many Stebro did, do you? Funny, i can't find anything on the internet about these Merco's.

TFF

http://www.modelenginenews.org/
You might email these guys; they might know.

Kmot

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cg: I got it from your auction!

I just did a search for completed auctions of Merco and found your engine. The info is in the question and answer section at the bottom.

canadagoose

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Ha Ha, didn't even see that Tom.

canadagoose

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Here's a couple pics of the engine torn down and all parts cleaned and laid out. They spent 6 six hours in a hot anti freeze bath. This engine was really gummed up! Some parts like the prop driver, rear bearing and cam box didn't want to come off. I managed to get everything apart without wrecking, bending or marking up too much. The cylinder liner and crankshaft don't have any ports cut in them, i didn't think the liner would but the crank was a surprise. In the upper left corner of the pics is a bunch of spare parts that came with the engine (cylinder head and valve gear, intake and exhaust manifolds, set of rockers and 5 extra pushrods as well as an extra lifter and some bolts). The bearings are not very smooth so i will have to try and order a set before re-assembling.

TFF

Get the calipers and lathe out and finish up a second. I wonder if the makers had access to unmachined parts like the sleeve and piston and could finish them like they needed. I see the piston has a port in it. I like the that the cam base cycle is so large; makes for a low stress action. Lots o parts in there.

canadagoose

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I was thinking that while i am waiting for some new bearings, maybe i'll measure the parts up with a micrometer and model them in 3d. Maybe Stebro did get some parts from Merco that weren't finished with ports like the crank and sleeve.

jjscott

I just love this oddball stuff. Thanks for keeping us posted on your progress. Can you tell if the rocker post and rockers are OS parts?

Jim

canadagoose

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Here's a couple shots of this engine back together along side an OS fs-60. I looked through my spare engine parts and found a rear bearing that was the right size, don't remember what engine it was for. It's interesting to note that the head port threads are the same in both engines as well as the crank threads. I threaded my spare exhaust manifold into the OS. Rockers and post are different though real similar. The Merco is definitely lighter than the OS. Can't wait to run it but that won't be for a couple days. The reassembly was a snap with this engine, it is quite an oddball.

Kmot

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Way cool!!! [sm=thumbup.gif]

TFF

I would like to know how it runs. I have a OS 60 that I fly, and a 75 in a box, waiting. I also have an OS 80 that would have made a great conversion like that.

downunder

I have to correct myself, it's not a Mk 2 as I said before. It's a Mk 3 heavy case with that large rib running down from the (old) exhaust port to the mount lug and the unused lugs that could be screw holes if a removeable front end had ever been fitted. That piston is almost certainly the 2 stroke piston with the baffle machined off because they had the two ports and a single ring. The conrod is standard Merco. The crankshaft may have been a blank from the factory because the normal 2 stroke crank could have been used with that small drive pin pressed into the hollow crankpin. The liner could also have been a factory blank but something like that would be relatively easy to make. Whatever, it's a fascinating engine .

Hobbsy

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Up until a couple of years ago I had two British engines called HiMax, a .91 and a 1.20, they were identical save for the bore. I sold them as they had just sat here in boxes for years.

canadagoose

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I have been running this engine a bit. Seems to have good power for an old open rocker 60 and idles great. All in all runs really sweet. Propped with an APC 12x8 it managed 8200 - 8300 rpm. This might be a little better than the OS 60 FS could do.

TFF

Cool! Is it going in a plane? I am running a MA 13-6 scimitar on my OS but dont know the rpm.

canadagoose

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TFF, it won't be going in any plane at the moment. I should check to see if i have a MA 13x6 to see what rpm it will do with that.

canadagoose

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I was contacted by Dave Brown, designer and builder of the Stebro Merco 4 stroke. What luck hey?
Anyways he has given me much info and history of these Merco engines that were converted. His email
is davidbrown444 at btinternet dot com if anyone else has some questions.


"To canadagoose. I am the designer and builder of the Merco 61 4 stroke. conversion. Just over 90 were made in the early 1980''s. I see that there are a number of people in this forum, including yourself, who have questions about the engine. I will do my best to answer them if they contact me.
Regards from Northamptonshire England"


"Hi Terry
Thank you for your reply. Re your motor No 69 this was a special built for J Tscharkowsky in June 1983. It was a conversion of a brand new motor and was built to a very spec. The only motor with a higher spec was the prototype which was about 10% faster back then.
Your comments about the power comparisom between the Stebro and the OS are correct. My motor was independently tested in March 1982 by Mike Billington (engine tester for our RCME magazine at the time) on the Santa pod dynamometer and she produced 0.68 bhp at 10000 rpm with 88 oz ins at 5300 rpm compared to 0.62 bhp at 10300 rpm and 75 oz ins at 6200 rpm for the OSFS60."