911hillclimber Posted October 29, 2021 Share Posted October 29, 2021 £30 chance buy because I likes it! Label said it is a Frog, but no markings. Rear back plate has '882D' just the item number and diesel I guess. However, I'm sure one of you will be able to describe it to me, more details the better! Not sure to clean it and display, or leave it and make or find a correct patina compression screw/spinner, or clean and get it to run as a project in the winter. If the latter, what size prop do you think? I guess the bore to be about 0.5" x stroke of 1" (ish) Finally, what thread type do you think is used?? Thanks in advance, Graham. Quote Link to comment Share on other sites More sharing options...
John Lee Posted October 29, 2021 Share Posted October 29, 2021 It's a Majesco, see here, about half way down, for more details: https://www.adriansmodelaeroengines.com/catalog/main.php?cat_id=50 The article references Col Bowden's Diesel Model Engines book which is available here: https://rclibrary.co.uk/download_title.asp?ID=1528 Being manufactured in Britain I would expect the threads to be BA. Quote Link to comment Share on other sites More sharing options...
911hillclimber Posted October 29, 2021 Author Share Posted October 29, 2021 That is quite a lot of detail! Thank you very much. Nice to have found it in such good complete condition. The head is different to the 743 shown in the article, but things would change over a run I suspect. It looks/feels like it would run and turns very freely. Need to find a decent 'propper' compression screw, the chrome screw in the engine is certainly not right. Thanks again, Graham. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted October 29, 2021 Share Posted October 29, 2021 Likely BA but don't be too sure. At that period many different screw threads were available and used so a small engineering business would have no hesitation in using whatever was available and suitable but it would most definitely not be modern metric. Beware any chrome screw as it is unlikely to have exactly the correct thread so may have damaged the cylinder casting. Quote Link to comment Share on other sites More sharing options...
911hillclimber Posted October 29, 2021 Author Share Posted October 29, 2021 Agree, the current part is seized in solid. Not sure if it will come out without stripping the head thread. Where can i go to find an old compression screw that may fit this engine? Nothing on ebay... Quote Link to comment Share on other sites More sharing options...
Rich Griff Posted October 29, 2021 Share Posted October 29, 2021 Seized in as in corroded in, gummed up and very stiff/stuck or solidly in because it's the wrong thread ? Any thread showing you could measure or compare with a thread gauge ? What is the head made from, alloy ? You could try warming the head and cooling the screw, it may free off that way....some cheapo carb cleaner when sprayed is very cold. Carplan do a spray called " freeze your nuts off" but has become impossible to get now locally sadly, it worked very well, but I discoverd tohe cheapo carb cleaner which was nearly as good, so use that instead when needed. Any sign of the chrome "lifting" ? Quote Link to comment Share on other sites More sharing options...
911hillclimber Posted October 29, 2021 Author Share Posted October 29, 2021 My main hobby is classic cars and old race cars, so freeing awkward threads is almost a weekly adventure...or disaster! will give it a go tomorrow. only 1/8" thread showing. chrome is perfect! If I know thread I can make one. looks 3/16 to me, but I'm a metric lad really, at college in 1970 so went imperial to metric along the way. Have a few old 60's diesels, but all are about 1/8 thread, this is larger, but not a 1/4. Are these engines rare or common place? Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted October 29, 2021 Share Posted October 29, 2021 I very much doubt you will find a compression screw anywhere. you will have to make one, preferably matching the original design. It may require so ingenuity. Quote Link to comment Share on other sites More sharing options...
911hillclimber Posted October 29, 2021 Author Share Posted October 29, 2021 OK, thank you. Never tried to fix an engine so old before. Making one not difficult, making it look a bit old is! Wonder why the head shape is different, less meat to carry the screw thread. Fuel cut-off is a surprise, never seen that before. Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted October 30, 2021 Share Posted October 30, 2021 (edited) That Head Looks strange . I bet someone has tried to convert it to a glow . Easy but time consuming job to turn a new head and make a new comp screw . They are not Hens teeth rare but not common either. Many have been destroyed or ruined over the years so to find one complete like your is good basis for an easy restoration and well worth doing. Good luck and hope you get it going . E.D. Edited October 30, 2021 by Engine Doctor Quote Link to comment Share on other sites More sharing options...
David Ovenden Posted October 30, 2021 Share Posted October 30, 2021 Looks a bit like a diesel version of this Spark ignition model?? Majesco 4.5P (4,5 cc.) (libero.it) Quote Link to comment Share on other sites More sharing options...
911hillclimber Posted October 30, 2021 Author Share Posted October 30, 2021 Correct, they went from plug to Diesel in 1947. The description in the 2nd post of this thread explains it all. The compression screw came out with a bit of persuasion and the thread is clean, just corroded. The chrome of the screw came off! I now have a working screw that looks the part. The contra piston seems jammed, but I filled the head with some oil, backed the screw off and eased so gently the engine over to push the c/piston up. Not convinced it worked. Going to leave it to allow the oil to penetrate the head parts.The sloted screws that hold the head on are TIGHT and I'm warey that things will get ugly if I try to take the head off to free the c/piston. The fuel shut off is all free as is the needle, and all parts are really nice and clean from damage. Some brake cleaner and a brass wire brush has removed a lot of the superficial staining and it looks smart. Turns over well and smooooothly, compression feels weak until I gave the inside a drop of oil. I am not convinced it is robust enough to start it... Quote Link to comment Share on other sites More sharing options...
Mike T Posted October 31, 2021 Share Posted October 31, 2021 If you firmly mount the engine and use a heat gun on the head, then a properly ground screwdriver should remove the screws without damage. The drawings in the article linked by John Lee show the head as only having a small locating flange on the underside, so the flat topped head on your engine has very little 'meat' for the comp. screw to locate in. It might be worthwhile verifying this and maybe get someone to turn up a substitute in line with the drawings and other pics? Given the size (2.2cc) of the engine, I'm pretty sure the comp. screw will be like most others of that era and have a BA thread. If you think it needs replacing, PAW can probably supply one for under a tenner. Quote Link to comment Share on other sites More sharing options...
911hillclimber Posted October 31, 2021 Author Share Posted October 31, 2021 Thanks, I think the engine is all BA and BSF. The screw, although (was) chromed is now raw steel and the thread is good, so is the head thread. Other pics of other engines show a raised turned section to give a deeper head thread, but this engine is a later serial number than others. The spark ign engines have a finned head. Diesels are not. Will give the head screws a go, but bothered about one/all shearing off, so some heat will help and also get some oil to the contra piston fit. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted October 31, 2021 Share Posted October 31, 2021 911hillclimber I would not try to move a stuck contra piton by any means other than completely removing the cylinder liner and gently knocking it up, or completely out, with a suitable copper or brass punch. With a stuck contra piston the conrod will simply bend or worse shear off the crank pin if you turn it over TDC using an hydraulic lock. Quote Link to comment Share on other sites More sharing options...
911hillclimber Posted October 31, 2021 Author Share Posted October 31, 2021 Totally agree, I wouldn't force the situation, which is why it is still in the engine cabinet while the oily mix seeps in I hope. Illtry to heat soak it and see if the screws yield without undue force. Quote Link to comment Share on other sites More sharing options...
David Davis Posted November 1, 2021 Share Posted November 1, 2021 I've heard that a good tip for a stuck contra piston is to dimantle the engine, heat and oil to taste then invert the cylinder onto a stout block of wood or similar surface. Find the largest piece of dowel which will fit into the bore then give the dowel a couple of smart taps with a sizeable hammer! I've never done this myself but I've been assured that it works by an expert engine collector. Quote Link to comment Share on other sites More sharing options...
brokenenglish Posted November 1, 2021 Share Posted November 1, 2021 (edited) It's this engine, which is basically a 2.2cc diesel version of the Majesco 4.5cc sparker. There was a second version of the diesel, with a very nice red plastic tank, with the word Majesco moulded in the plastic. They're nice runners but the mounting lugs are very thin... If you want to run it you'll need a fairly big propeller. From memory, I think mine ran well on an 11x4 wood. On the earlier spark ignition engine, you would have seen the engine marking, because the exhaust is only on one side, and the transfer side has an "M" logo cast in the transfer port cover, but the diesel has exhausts on both sides, so no identifier (but lots of discussion...). Edited November 1, 2021 by brokenenglish Quote Link to comment Share on other sites More sharing options...
brokenenglish Posted November 1, 2021 Share Posted November 1, 2021 This is the second version of the same engine. Quote Link to comment Share on other sites More sharing options...
911hillclimber Posted November 1, 2021 Author Share Posted November 1, 2021 Interesting pictures! Mine I think is quite late, # 882, no idea how many were made. It has the head of the above later engine, the comp screw is exactly like that but mine was chromed steel which I literally wire brushed off, the screw though has no stop. It has the clear plastic tanks, but has the spring assisted timer on the tank top casting (possibly edited out on the first pic?) So, could well be a 'transition' engine with a mix of parts depending on what was in the stores at the time? As said already, the mounts are light and the extended nose for the crank equally light, would not take well to a single point landing... Quote Link to comment Share on other sites More sharing options...
brokenenglish Posted November 1, 2021 Share Posted November 1, 2021 OK, the two that I've shown in my photos above have the following serial nos. The early one (like yours) is D817 and the later one, with the red tank, is D935. One interesting point, that hadn't occurred to me, is that the D prefix probably means that the actual digits were simply carried on from the earlier spark engines. I have two of the spark engines, and their serial numbers are 6 and 212, without any prefix and both earlier than all our diesel numbers. Quote Link to comment Share on other sites More sharing options...
brokenenglish Posted November 2, 2021 Share Posted November 2, 2021 One last comment. I've just read the early posts and you mention "stuck" screw threads. Here, your car restoring experience is leading you astray. If a car engine or body has jammed solid threaded fasteners, you can't just "put it in the oven"! IMO, you should try removing the plastic tank, and then put the entire engine in the oven, at about 200°C for 20 to 30 minutes. I would be very surprised if you were unable to turn/remove any screws after that (I've done it very many times), partly because the alloy outer casings expand more than the steel screw shanks, and partly because the heat will soften any congealed gunge. Quote Link to comment Share on other sites More sharing options...
911hillclimber Posted November 2, 2021 Author Share Posted November 2, 2021 Good tip esp as it works! Thank you. Will give that a try. Done nothing today on it, busy, oddly, stripping a 3.2 litre flat 6 air cooled engine..... Quote Link to comment Share on other sites More sharing options...
Rich Griff Posted November 2, 2021 Share Posted November 2, 2021 (edited) Oh, nice, some pictures please....Lycoming ? Edited November 2, 2021 by Rich Griff Quote Link to comment Share on other sites More sharing options...
Kim Taylor Posted November 2, 2021 Share Posted November 2, 2021 (edited) 21 minutes ago, Rich Griff said: Oh, nice, some pictures please....Lycoming ? I think 911's username gives it away. Or maybe easy for me to say as I've been following his trials and tribulations with his Lola-Porsche for some years!! ? Kim Edited November 2, 2021 by Kim Taylor forgot how to write english!! Quote Link to comment Share on other sites More sharing options...
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