General Discussion

Greetings! Noting that a lot of folks quite rightly don’t know where to look on this site to add a comment on a topic for which there’s no established thread, I’ve set up this new thread which is intended as a place to post any and all comments on any subject for which no specific thread currently exists. I will monitor this thread regularly, and if a topic comes up that appears to warrant its own thread, I’ll create a new separate posting for that topic.

Hope to hear from some more of you!!




126 thoughts on “General Discussion

  1. Hi Adrian, Great site, I am a collector of early Japanese engines and enjoy your vast knowledge of engines. I have three Hope 29 parts engines, 1 ignition version, 1 glow version and 1 I cannot work out what it is. It has Hope 29 stamped on the side with letter and number stamps and when I put it beside my Kotobuki 29 the crankcase looks the same with the venturi attached to the cylinder,not like the Hope B where it is separate. I can send photos if you can give me an address. Peter.

    1. hi Adrian

      its Paul from England, have lots to talk about with you but have moved addresses and lost my email account, i lost your email adddress as well, any way of getting back in touch with you


  2. Something I would like to see is head to head comparison of 1.5cc RC muffled diesels like PAW and ME Snipe and Taifun and AM and Cipolla and such. I’ve seen the mufflers. I’ve seen the throttles and I’ve run a PAW.09 with an 8-4 four blade prop. (scale fun!) but there is still so much I’d like to know about this modeling niche. All for now, Thanks, Paul

  3. Adrian, in light of your current July article on Mills numbering I’ve gone through my inventory of originals and have 15 sets of serial numbers covering 1.3s, 75 mk2 and a solitary 2.4 to add to your database. Can you get in touch via email.

    Chris Murphy

  4. Hello Adrian et all. I have a lovely AM 35 and the previous owner had bodged up the holes on the bearers. There are many misdrilled holes. Is there a source out there for used diesel engine parts for vintage? I would love to restore this engine very much. I am living in Ontario, Canada.

    1. There’s no particular source of parts like that, James – it’s a matter of finding someone out there who has the part that you need and is willing to pass it along to you. I checked, and I don’t have such a component. Anyone else out there able to help James?!?

  5. Adrian, I really enjoyed your piece on Dunham Engineering. In your article you postulated on the origins of the name the Holmes family chose for their company. I think I may be able to shed some light. I was friends with Barry for many years and once asked him about the name Dunham. He told me it came about from the family frequently proclaiming “Done Them” as this passionately productive family would finish another set of jobs. “Done Them” in a Lancashire accent sounds a lot like “Dun ’em!” Hence the name. Best regards, Simon Bennett, Portland Oregon, formerly of Wigan, Lancashire.

    1. Thanks, Simon I’ve added that information to the Dunham article with full acknowledgement.



  6. Hi Adrian,

    A technical question. From time to time I’ve needed to make heads for glowplug engines. Compression ratio and squish clearance aside, do you know of a reliable formula for optimum glowplug face to piston distance at TDC?

    1. I’m scarcely an expert in that field, Maris. I think that an excellent source of information would be my good friend Johnny Shannon. I’ll put you in touch.

  7. Adrian, Besides the Hope Super 60 ,I also have a FUJI (7300 stamped on the block). Do you know any thing about it? Anyone?

    1. Attachment

      Don, Any news on your Hope 60? Have you read Adrian’s article on the early Fujis? Meanwhile I have acquired another 60 Super Hope in the glow version apparently, although it uses the ignition crank shaft and front casting. I have also found that another 60 Super Hope probably exists in the collection of a millionaire car buff friend of mine. So from memory I decided to make an inventory of the 9 or so Hope 60s I have seen or heard of. This led me to the Miguel De Rancougne auction where apparently two ignitions and a glow version he found sleeping in an old Tokyo hobby shop, were auctioned off.
      To anyone reading this and that has the catalog on these engines could you possible describe the motors or give any info you have on who got them? Are they new finds not pictured any where on the internet? Sandcast or machined timer, olive or light green, 5 or 7 fin cylinder block?
      I am trying to get pictures of the one I found with the millionaire. The motor in the included picture is my new job with rear piece not in correct position. Needle valve should be up and facing vertically with a few degrees of slant away from the exhaust side of the block. Thanks, Paul

  8. Hi Adrian,
    This is on the VT engines. My father is the younger brother of the two VT. He is currently ok at 88years old living in New Mexico with my mom and brother. If you like I can ask him to get more specifics on the write up but I need to tell you the work you did is truly a great piece of historical information probably for collectors, but to me goes very deep and I treasured all of what you were able to put together.

    András Vella
    Nephew of the older brother of VT

  9. András, great to hear from a member of your honored family! I’d be most interested in learning more about the Vella engines from your father. I’ll be in touch by direct email.

    Thanks for the contact!

  10. A junk stall has recently supplied me with a DC Spitfire. Having extracted it from a liberal coating of congealed oil and grime, with the exception of the con rod which is badly worn, it’s general condition is not too bad so the intention is to make a new con rod to allow at least demo running.
    My problem is that the wear pattern makes it very difficult to establish the spacing for the original hole centres. As most of the measured dimensions are very close to imperial fractional sizes and my best estimate for the hole spacing is 0.678 inches I am inclined to think that the original design value was 5/8 (0.675) of an inch but it would be nice to have this confirmed if anyone can.


    1. Mike

      I’m not an expert like many who inhabit these pages, but if you are stuck then I’ve got several Spitfires and I’m happy to get the measurements you need.

      I don’t think the dimensions are absolutely critical to the nearest thou’ though so your best estimate should at least give you a runner?

      Let me know anyway.


    2. Can’t help with your question, but I have another related one. The DC Merlin/Spitfire/Sabre and others of similar design have three exhaust slits in the cylinder. The crankcase has two. The cylinder can of course be assembled in any position relative to crankcase exhausts, but naturally, there is significant blanking of at least one port by the crankcase.

      So does one best assemble things so that two cylinder ports are almost unobstructed (leaving the third more or less blind), or should the cylinder be set to allow one port free breathing and the remaining two ports roughly half exposed to the opposite exhaust slot in the crankcase?

      1. This is an old question with these engines. Personally, I’ve always assembled them with one port fully open to one of the two crankcase exhaust ducts and the other two ports “sharing” the opposite duct equally. At least this way all three ports get a reasonable exposure to an exhaust duct. Half a loaf is better than none! I usually assemble them with the wide-open port on the right (looking forward in the direction of flight) and the two “sharing” ports on the left. In this way, the column of metal between the two “sharing” ports assists in resisting the side-thrust generated during the power stroke. I generally mark the column between the “sharing” ports so that I can always reassemble the cylinder in the same orientation if dismantling is ever required. That said, it might be interesting to try the effect of assembling the engine with one exhaust port almost completely blocked ………. something to try sometime.

    1. Merci beaucoup, mon ami Michel! I’ve amended the relevant Wotizit page with full acknowledgement for your help.



  11. Hello!

    Great site.

    I read your text in Model Engine News on the Zeiss U-boatlike 2 cc diesel. The one with the text “Lehrbetreib” cast onto the crankcase. Very interesting historical essay on the period!

    I have no evidence, but do feel that “Lehrbetreib” was put there to transmute the engine from a frivolous toy squandering State resources into a stepping stone educating youths that the State needed as future technicians.

    A comparison: In Sweden, modelling had some State support despite often being regarded as a hobby with toys. The rationale was that a large number of fighter pilots had to be trained every year. Trainees with modelling background fulfilled the training on schedule a lot more often than young men without that background.

    (I flew TR in Sweden. In 1962 my team mate Goran Alseby and I participated in the East German Nationals. We did win the FAI TR class. We saw no Zeiss engines. Their existence was unknown to me until I stumbled upon that MEN article.)

    Mans Hagberg

    1. Thanks very much for this, Mans! I think that your explanation for the marking on the engine is most probably correct – makes complete sense. Unfortunately, I can’t change the article on MEN since Ron didn’t leave us with the means to access the site to make changes – he left it tightly locked down with no key!

      The best that I can do is mention your comment in the next Editorial due out on December 24th of this year. I really appreciate the input, and won’t allow it to go unshared.

      BTW, did you ever encounter Luis Petersen of Denmark in your T/R adventures? He’s a great friend and valued colleague of mine.

  12. Hi, I was very interested to read the excellent article by Adrian and David about the History of Mills Brothers. I have a website on which I have been gradually presenting material about Milbro model railway products ( I knew a little from other website materials about the factory in southern England making aero engines, but was surprised to learn about the apparent discontinuation of the railway models output from Sheffield at the end of the 1940s. Advertisements and catalogues continued to be produced under the Milbro name from Sheffield through the 1950s, featuring model railway items. I am wondering therefore whether the position on rights to the Milbro logo and name was more complex than was perhaps implied in your paper. The last dated model railway catalogue I have with the Milbro trade mark featured on its cover is dated 1957-58, and gives the St. Mary’s Road address in Sheffield for Mills brothers (Sheffield) Ltd. I have an additional undated catalogue that is probably a year or two later, although its date cannot be verified. Such catalogues come up quite frequently on Ebay, so I think that a substantial number must have been produced. Track and other items were certainly still being offered at that time. I have not tried to survey the Mills company history systematically for my website, as my focus is essentially on chronicling and describing the model railway products. On the other hand, if anyone knows a bit more about the relationships between the Sheffield factory and the other parts of the firm in the 1950s I would be glad to hear from them, so that I can add to the brief commentary I have included on my site so far. There is a facility with my website for sending me an email if anyone knows more. Best regards, Malcolm

    1. Many thanks indeed for this information, Malcolm! Since my research database relates mainly to model aero engines, I had no knowledge of any Milbro model railway activity after the model engine manufacturing was concentrated at Woking. It seems from your comments that what really happened was that the former Mills Bros. company was divided into two distinct entities. The original company (Mills Bros. (Model Engineers) Ltd.) continued at Woking making model engines, while a (presumably) separate company (Mills Bros. (Sheffield) Ltd.) was established to continue making Milbro model trains in Sheffield. Since Arnold Hardinge was strictly a model aero engine guy, I assume that when he took over the original Mills Bros. company, his first act was to divest himself of the model train business by selling the model railway side to a Sheffield-based associate (perhaps one of the “original” Mills brothers?!?) who was more interested in the model railway business and wished to maintain production at the Sheffield premises. All that I know for certain is that model trains were never made at Woking – Arnold Hardinge never displayed any interest in model railways.

      Thanks again for your most valuable input! I’ll amend the Mills model engine article accordingly, with full acknowledgement.

      1. Many thanks. Yes, I think you are probably right. A division into two entities does sound like the most likely explanation. I will amend the bit of commentary about the post-war companies on my site when I next do an update (I am very slow !), and will reference your article when I do so.
        All best wishes for your network and site.

  13. Hi Adrian, Just tried to join yourwebsite, but see you have to be in USA or Canada. I am in Australia …. Could you consider putting this onto a new thread please. Kind regards .. Ed Holly

    Designer / builders of Model diesels

    As we all know Ron Chernich did some wonderful things for the model engine enthusiast and his website remains a beacon for all of us interested in model engines. What Adrian is doing on this website is terrific, and I think will become the best way that like minded guys interested in design of model engines might stay in touch.
    Ron was part of a band of guys who had a unique part to play in the development, design and handling of these engines and sadly with Ron’s passing we now don’t get to hear from them and they were of course called the Motor Boys.
    I was very lucky to have known David Owen for a few years, and David encouraged and guided me through the early part of engine building. If ever I got to know 5% of what David and the other Motor Boys know and knew I would be very happy, such is the esteem I hold them all in.
    I wonder now if the fun of designing model diesels is being lost, diesels are no longer in favour in modern aeromodelling, we are now firmly in the electric arrive by post this morning and fly this arvo era, however there is an immense amount of fun, enjoyment and satisfaction derived from making some blocks of metal into a living breathing entity and especially when to your own design. Of course another scourge of diesels is obtaining ether, but usually where there is a will there is a way.
    Through this blog, I would like any other diesel model engine designers to put up their hand. I think the criteria should be to have designed and built at least one engine and seen it through to completion and running.
    I have been lucky enough to find the time to build 15 diesels from .5 to 4cc – 5 of which are totally my design and 5 are modified designs of engines from the Motor Boys plans. These include 2 Vee twins and an inline twin.
    So if you fit this criteria, please add to this blog. I would be terrific to share some knowledge and ideas with some like minded souls.
    Finally, my last design is written up at and it takes the engine from an idea through to it running with good power and handling, being a 2.5cc single ball race diesel. With this design and write up I try hard to inspire others to have a go …

    1. Thanks for this, Ed! This is indeed a great suggestion! I will start a new discussion thread on this blog entitled “Home Construction of Model Diesels”. Your post will kick it off!

      Thanks again!



  14. Hi Adrian ,

    Is there a special reason why one can not register on your website outside Canada and the USA

    Regards from Belgium , Jef Lemmens

    1. Jef, I’ve explained several times (but perhaps need to do so again!) that the registration thing on my site means absolutely nothing. It’s an artefact left over from the platform’s intended use as a commercial sales site for North America. I asked about getting rid of it, but unfortunately it goes with the territory! It has absolutely no connection with the use that I make of the site.

      Anyway, bottom line is that registration has no effect whatsoever! I’ve previously advised folks not to bother, and it seems that I should do so again.


  15. I have a lovely old Majesco 45 casting set in its original box currently sitting on my dining table that is asking to be my next build…

    The problem is that it is cute and it seems a shame to change what is clearly a piece of model making history into just another engine. It is a very nice die cast castings set 🙂 and the temptation to make the engine is getting higher…


    P.S. All currently underway castings sets/engine builds and are stored on the dining table before visiting the workshop.

  16. Hi again,

    I read the article on diesel fuels with great interest. Very informative! In olden days you had to mix your own fuel. The ingredients were not that hard to come by in the fifties and sixties .

    In the early sixties I tried to make a T/R engine less “fuel cooled”, less prone to need added fuel at the end of the tank. I made a 30 mm shrunk-on tightly finned jacket for an ETA .15 . A 10 mm aluminium comp screw transmitted heat from the contra piston to the jacket.

    It worked well but not well enough. The engine still needed to use fuel for cooling. Your article of 2015 gave me a better grip on the situation than anything i read then!

    I used a conservative mixture of 30 ether, 30 castor oil, 40 kerosene plus 2,5 amyl nitrate. I checked performance and consumption and this mixture actually compared well with others using less oil.

    One note on your article:

    Amyl nitrite (not amyl nitrate) is the heart stimulant. In the 1950-s British team race guys used the additive with some success. I got a special permit from the local authorities to try it out with a pledge to use it only outdoors well away from people. On one occasion I inadvertently inhaled some. The ensuing pulse race really scared me. So I never used that additive again. (And it was no better than amyl nitrate, probably a little worse.)

  17. Thanks for that, Mans – you are of course quite correct! I’ve amended the article accordingly. Mind you, amyl nitrate is still pretty nasty stuff……….

    I too tried amyl nitrite at one point. Like you, I found that it actually didn’t work as well as amyl nitrate. I did however manage to avoid inhaling any of it!

    These days I use octyl nitrate, which seems to work pretty well and doesn’t carry quite the same level of health hazard. However, it too should be treated with respect.

    Cheers, and thanks again!

  18. Re Feltham Flyers Part 2
    Rivers Silver Arrow 19
    I have C 462 in my collection, this is only 9 away from the case number you mentioned. I purchased the motor from the US last year, I have no idea of its history before this.

  19. Hi Adrian –

    just wanted you to know I enjoy your site… I certainly appreciated the excellent SHARMA article from this month…. from your information, my 3.2 D is an early model…..

    Best Regards,

    Jeff McCammant

    1. Thanks, Jeff! Those engines really are a lot better than one might expect – I’ve certainly had great service from mine! Glad you liked the article. I have one coming on the other Indian manufacturer, Aurora of Calcutta. Stay tuned ………..

  20. Dunham Engineering article

    Hi Adrian
    I have just read your piece on Dunham, and feel in the interests of historical accuracy it deserves comment.
    Dunham were not under appreciated, they where victims of themselves. Firstly look at how you report their customer service, and the fact that manufacturing defects were common. To cap it all they continued to produce engines for which there was very little demand. A good business understands its market, Dunham obviuosly made no effort in this respect.
    Great Britain was a far different country to the one you portray. When Thatcher took over it was the basket case of europe, but very soon her policies created a very prosperous period , encouraging home ownership and low taxation. In this enviroment other engine manufacturers and importers emerged that prospered becuase they understood what the niche market was that they were aiming for.

  21. I was looking over my Frog 500 Glow and reading your tome on Ron’s site regarding it.
    Mine has baffling (to me) serial numbers.
    upright on the edge of the right mounting lug “JEN”
    Rotating the engine on the bottom of the right lug “IFS”
    And on the bottom of the left lug “253”

    There are no hand inscribed numbers anywhere.

    What do these stamps indicate?

    1. Ivor F. Stowe habitually stamped his engines with IFS and a number in his collection sequence. I reckon you have one. Not to be confused with any production serial numbers. FROG crankcases- as spare parts – did not carry serial numbers.

  22. Hi Adrian,
    your BONNIER is a first serie. there is an error in the french book. second serie is with nut on the head.
    I have: serie one S/N 421 and serie two S/N 2473


    1. Thanks, Michel! I was going by the French book, which I now understand to be in error. I will now have to significantly amend the article, which was all finished and ready to go! Lots of work and not much time, but I have to get it right! Many thanks again!

      Cheers, Adrian

    2. Michel, I need to know whether or not both models of the Bonnier had tanks. The second model illustrated in the French book has a tank. Does your second model example have one also?

      Cheers, Adrian

  23. Adrian,
    both series havent tank. the only one without is the car model due to the two wheels. the tank is always with cut off for carburant.


    1. Thanks, Michel! I assume that you meant to say that both series HAVE tanks except for the car model?



  24. To all. Does the DS in PAW DS indicate diesel squish? Would the contra piston have a hemi profile with a squish band area?

    1. Yes, that’s just what it means. The contra piston has a squish bowl formed in its underside. However, almost all of the ones that I’ve seen have been too small in volume to do much good. I usually enlarge mine somewhat.

        1. I meant enlarge the bowl. As delivered , the bowl tends to be a bit on the small side. Keep the squish band more or less as-is. Don’t overdo it, though – you can’t have direct contact between piston crown and squish band when at running settings.

  25. Adrian,
    Re your article on Majesco engines. I am in the privileged position of being Jack Colyer’s son-in-law through my marriage to his daughter Rosanne, and am aware of much of the history regarding these short-lived engines. The MA in the name Majesco was based on the initials of my mother-in-law Miriam Annette. The move from Littlehampton to Parkstone was based purely on expediency and a desire for some family independence as the Littlehampton address was the home of Jack’s parents-in-law!

    If you need any more info please contact me.

  26. The thing I’d like to see is a glossary of engine design terms for breathing and timing an engine. The subject of modifying or rebuilding comes up often with me. This also raises the question of torque, as getting and using scale propellers is a problem with me in this hobby. Which are the torque strongest engines, preferably with ignition or RC/muffled? How does it equate to pulling power and flying?
    The few problem solutions to this I am aware of are: diesel, flat pitch, torque, reduction drives, and…………..thanks, Paul in Thailand

  27. Hello Adrian,
    I read your article on the Sharma diesels. I was impressed by the 3.2 cc model. So impressed, I bought one directly from Mister Vivek Sharma. These engines rival the PAWs in every way. Mine out performs my PAW .19. I’m quite happy with the quality of materials and machining on these.

    Jim West in Ontario

  28. Thanks for that, Jim! Yes, they are indeed one of the best-kept model diesel secrets. I’ve been a Sharma user for 20 years now, and have never found anything about which to complain. Glad you feel the same!!



  29. I just purchased an early Delmo 2.6cc diesel serial #116 that seems to have some problems. Everything I have read says the compression is adjusted by the liner moving up and down but mine is not responding to movement of the lever on top which I might add is also bent and overriding a cut down stop protrusion in the top of the cylinder similar to the Swiss Dyno. Looks like someone was having problems with the engine. Can any one comment on this engine before I dig into disassembly? Also does any one have spares as the intake hole cover and screw are missing. Possibly too there was a small spring.
    Thanks in advance, Paul

  30. Hi Adrian.
    Could not find a comment on the Frog 150R article so I dropped on to this thread.
    I have two late 150R I think produced by DC that do not have a bushing for the crank and a bolt instead of a threaded shaft. The shafts are larger diameter to take up the space of the missing bushing. These engines have a reputation of being more powerful than all the previous Frog 150Rs, we used them in a, now not flown free flight class in the UK .

  31. Dear Adrian,

    I read your Zeiss Pioneer 1 article various times and like it a lot. The detailed description helped me to understand its functionality in detail and to restore such an engine. Whenever I read an interesting engine article, I try to find a video clip online to experience the engine visually running and to hear its specific sound. As I could not find a running clip of this engine online despite looking really hard for it, I decided to contribute by filling this gap.

    Thomas Hantschel

    1. Thanks for this, Thomas! A fascinating engine indeed! I really appreciate your sharing this with us!



  32. Hi Adrian, just read your very interesting article about the composition of diesel fuel. As a boy in the late 1950’s, early 60’s in the UK I used to make my own fuel, as ready mixed was beyond my pocket money. This involved going to the local Chemist / Pharmacy to buy the constituents. I must have had an innocent face as after a few questions I would leave with bottles of ether, castor oil and amyl nitrate. Reading your piece I’m amazed I am still here to tell the tale! The engines I used included aero and marine versions of the Frog 3.5cc and the wonderful 8cc Taplin Twin 2 cylinder, which had the ability to run both ways. This resulted in the loss of several boat props. Best wishes, Peter.

    1. Thanks for the comments, Peter! Yes, those were the days! As a teenager growing up in Sheffield, I used to get all of my combustible diesel fuel ingredients just like you, over the counter at the local chemist shop. Also bought methylated spirit to fire my steam engines. I must have gone home carrying many a very incendiary load! Like you, I’m amazed that I’m still here!! I got my castor oil through my connections in the motorcycle racing world, a sport in which I participated for many years beginning at age 16.

      I also did model boats, mainly using E.D. marine engines.

      Great memories of a more innocent time, now sadly lost forever.



  33. Dear Adrian,

    I read your Zeiss Pioneer 1 article various times and like it a lot. The detailed description helped me to understand its functionality in detail and to restore such an engine. Whenever I read an interesting engine article, I try to find a video clip online to experience the engine visually running and to hear its specific sound. As I could not find a running clip of this engine online despite looking really hard for it, I decided to contribute by filling this gap.

    Thomas Hantschel

  34. The small Dyno replica. It looks like the Arnie Hende 0.6cc version. It looks to be the ABC version which wasnt very good and replacement steel cylinders were made by Pfeffer.
    Pfeffee also made complete 0.6 Dyno replicas as well, usually with anodised cylinder and prop nut.
    Enjoyed the Micro article and the test echoed my own CS version performanc

  35. Hi Adrian,
    r.e. the very unknown blue headed 2.5 diesel, the milled out interior of the exhaust
    stack, leaving a bridge in the middle, and the general surface finish of the crankcase
    and backplate are very similar to the same features on a Super Sokol 5cc. diesel
    I bought from Mike Clanford in the early ‘Eighties, so perhaps it is one of Mr. Gorski’s
    (Polish) engines?
    Do you have any experience with the Super Sokol 5 diesel? Mine was badly fitted but eventually ran well in a control liner with a 12×6 or 11×8.
    ran well on a 12×6 or 11×8. (control line).

    1. Good suggestion, Robert! Any clues of that kind are very helpful. Jim Dunkin’s 2.5 cc book does not list a Super Sokol 2.5 cc model, but that doesn’t necessarily mean that no such engine existed. A number of Gorski’s 2.5 cc models do appear, but none remotely like our mysterious stranger. Still, your suggestion certainly has merit. The other suggestion that I’ve had is that this may be the early work of Hans Drenkhahn of Germany. Let’s hope that someone can eventually nail this down!! Thanks for the comment.

      I have no experience with the 5 cc Super Sokol, but would like to gain some!! Never had the chance to acquire an example.

  36. I have just read your article on the Mills Diesels and noted the comments about there being no .75 models reported within the 45000 to 47000 numbering bracket. On checking mine I found that its number is 45985. I thought you may be interested. I have owned this engine since I purchased it second hand in the early 1960’s.

  37. Hello Mr Duncan,
    I read on the editorial that the article on the Ken 61 engine is completed, I am really happy, as I am very interesting in this engine. I bought a nice example of Ken from Tim Dannels, it is missing the needle valve. Can you help me with drawing, or some friend can get me the spare part? in the meantime I’m waiting for the article…Thank you very much, best regards
    Ernesto Pizzi, Messina, Italy

    1. Ernesto, I can certainly provide specifications for the needle of the Ken. It may take time – I’m really busy at the moment, but I’ll do what I can’

      I hope the article was of interest!



  38. Attachment

    Hi Adrian,

    Happy New Year from Brisbane! I’m posting to send a word of thanks for this site, and in particular the article about fixed compression diesel operation. I recently acquired a Drone Mk2 that, on cleaning up, turned out to be in very good condition indeed. I’ve been running diesels since I was a teenager in the early ’80s, and still have and fly the PAW 19DS that started it all for me. But, having never before seen, let alone run a fixed compression diesel, I turned to your article for advice.

    I mixed up some fuel, conservatively going for 28% SAE 30 mineral oil, 72% ether. On dropping a tiny bit in the venturi and flicking, I was promptly rewarded with a nice loud “bang!” and a puff of white smoke, then a rather more convincing burp on the 2nd flick.

    Getting an actual run was a little more challenging until I found the correct starting needle, after which it seems that it is trivially easy to get going. Once I realised a slightly lean start is the go, it became apparent that contrary to the mythology this is one of the easiest handling engines of all.

    Hopefully these video links to my Google Drive work.

    First run.
    Definitely lean (white puffs), and probably over-propped with the APC 12×6 I used for the first start.

    I switched to a MA GF3 11×6 for subsequent runs, which allowed it to rev more sensibly. Here it is making a glorious noise peaked on the 11×6.

    If anyone can point me at the plans for Bob Tucker’s “Hot Rock” I’d be grateful. This engine deserves to fly.

    Colin, Brisbane, Australia

  39. Aloha Adrian, from the island of Hawaii. I just wanted pass along my great appreciation for this wonderful resource. As all of us collectors know, it can be difficult to find information on these little gems. I just finished reading your fascinating piece on the Soviet Kometa – what a different picture than the narrower view Warring’s article presented!
    Thanks again!
    Kind regards,

    1. Yes indeed, the Kometa is a far better engine than its reputation would suggest. Glad you found the article useful!



  40. Attachment

    Aloha again Adrian,
    Well, here I am, right back with a bit of a mystery, to these unseasoned eyes anyway. Someone just passed along this rather nicely kept little engine, which I am pretty sure is a reproduction of a 1930s era engine, but if so, which one? I have scoured every place I can find pictures of engines on the web in an effort to ID it, but alas, I’ve not found anything exactly like it. It has what looks to be a serial number, ’38’, stamped on the starboard lug. I suppose this might more properly belong in ‘Wotzit?’, but I’m not sure of exactly how to submit for that section. Any help that yourself or anyone might provide would be greatly appreciated.
    Thanks again for such a great resource.
    Best regards,

      1. Thanks Adrian. I suppose it really could be a one-off, but being side-port, spark ignition, I’d be sort of surprised that someone would go to all the trouble of scratch designing a new but dated by design engine. I haven’t taken it apart (if it ain’t broke, don’t fix it), but it seems very nicely executed. Thanks for having a look.
        Kind regards,

    1. Hi Adrian and mahalo for adding it to Wotzit. Maybe someone will help us . I forgot to point out, in case anyone overlooked it, there’s a US penny in the frame for scale. Thanks again and I love your articles!
      Best regards,

  41. Aha! Thanks Dave, that gives me something to go on. I’m going do some more digging, with that lead in mind. I’ll report back.
    Best regards,

  42. No question – that’s what it is. A .19 cuin. unit made in around 1981 by John Morrill. Nice motor!!

    Thanks, Dave!!



    1. Indeed, that is exactly what it is. Thanks so much to you and David! With that information in hand, I was able to root about the web some more, and it appears to be patterned after a Lindberg Hornet .19 from around 1939, which I had never even heard of before.
      All the best to both of you and keep the good work up, Adrian. Believe me, it is appreciated!

  43. Adrian,
    The reasons we became attached to a particular engine, in some cases appearance, how it operated, value, reliability etc. One could enjoy just holding an Oliver Tiger in your hand but I fell in love with the Webra Mach 1 when I heard one running in a combat model, singing a sweet song as Brian Winch used to say.
    My Fox15 schneurle didn’t especially impress until I ran it. A sweet unit indeed. Certain designers developed their creations until they evoked such emotion. The K350 I own was a curiosity until I ran it. Then I viewed it very differently and wished I’d bought two to use, one for the display cabinet. I’ve never run a Mills but I’m sure they have that quality.
    Three british diesels were a big disappointment yet other folk loved the very same engines, I was unfortunate (when it was good it was very very good).
    Thanks for operating your site.


    1. It is indeed interesting to contemplate the reasons why certain engines become favorites. Sometimes it’s the way they run and perform in the air, sometimes it’s the way they sound and at other times it’s just the way they look and feel. In my case, another reason is often the story behind them. All are valid!

      You re quite right about the Mills engines – they have several of the qualities mentioned!

      Cheers, and thanks for writing in!

  44. When I was about 12 years old I became involved in control line flying with a group of local lads. We reckoned nothing to Mills 0.75s or anything smaller, as they just didn’t cut it as control line engines. We did once make a lightweight with an ED Baby and laughed ourselves silly as it staggered around the circuit, barely able to drag the laystrate with it. No, it had to be at the very least an ED Bee or better still a Frog 100 (Mk2?). The dad of one of the lads worked at ED (Molesey Rd I think) and when they came up with the ED Super Fury it was a revelation – with that engine you could do anything with something like a KK Gazelle (scaled down Peacemaker I think). Nothing else of similar size (and affordable) could touch it, though the PAW equivalent came close. We soon had our hands on a Rivers Silver Streak and a Silver Arrow – courtesy of ED of course, they must have bought them to see what the opposition were up to. These days it’s FF for me and I really do appreciate the qualities of the Mills engines, though I will always revere the ED Super Fury.

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    What happened to Marc Linville and Technopower Engines?? He is not responding to email and no web site either. Sell business, passed on, I don’t know? Any help please? I’m rebuilding a 5 cylinder and have two others I’ll run soon. Thanks, Paul Venne in Thailand

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      Glad to report that Marc has checked in with me. Not dead! His internet provider jacked up his bill to $695, or something, per month so he hit the ejection button and got back to work. All is well and thank you for your fine attention, Paul L Venne/Bangkok

    2. To answer my own question: He got a jacked up bill from his internet provider and had to switch so was out of touch for a while. I heard from him and he is chugging along and usual building and servicing and may have by now restored his site with a new source.

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    Aloha Adrian!
    I just picked up a little Super Hope .29 on ebay and would like pass on my thanks for your great article on the Hope engines. When I saw the ebay listing, I, not being an expert by any stretch of the imagination, had never even heard of them before. But, I knew where to start looking and sure enough, your article was there to help! Because of the rather dark color of the metal used, it doesn’t really show that well in photos, but I chanced buying it anyway and when it arrived, I was delighted to find it in really top shape, with excellent compression. A very nicely crafted engine indeed, as so many of the Japanese engines are.
    Thanks again and keep up the good work!

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    Dear Adrian,

    Some time ago I acquired a swell little Fuji .099 and later sold it to get more funds for my Fox collection; foolish move!

    In any event, its serial number doesn’t seem to fit into your index in Ron’s forum. Any thoughts on where it belonged?

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    Dear Adrian,

    I just acquired a Frog 175. I really appreciate your newest article on the early Frogs, as mine wasn’t quite matching up with the earlier one in Ron’s forum. I{n any event, my frog is fitted with a spark (?) plug I’ve never seen. Can you shed any light on what it might be. The screw head like “electrode” in the cavity is insulated from the body and has an .019″ gap around it, so it could spark there.

    Also, my Frog has a standard right hand thread

    1. That’s a new one on me, Bill! I suspect that it’s a home-made item – there were quite a few of those kicking around.

      Most of the sparkers had right hand threads. It was the diesels that went left hand, for reasons which escape me!



  49. Hello Adrian
    Need your help with ed 2.46 with serial number YH L6/8
    It has a red head and spinner….i was led to believe it should be green ?
    Can you shed any light ?


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    Hello Adrian

    I’m tremendously impressed with your site, I’m a lifelong (recently somewhat lapsed) aeromodeller having started with a DC Merlin as a ten year old in the late seventies.

    I’ve recently bought a NiB DC Merlin from ebay and found it to be as lacklustre as I recall my one from 40 years ago being!

    Now, back then although I’d heard all about Oliver Tigers, I could never afford one. So, again via Ebay, I’ve just bought my first, photos attached. It’s apparently a MK2 Cub.

    I’ve already bench run it on an 8×4 and MT D1000 fuel and it’s one sweet engine. Starts great and pulls like a train plus, unlike the Merlin I’ve just acquired, its compression screw doesn’t unwind all-by-itself when it’s running!

    The seller from Belgium informed me, when I asked him pre sale, that the chamfer that’s on one side of the head was hand filed by his late father to mark the engine as his – classy!

    Only on receipt of the engine did I notice that the entire cooling fin row one up from the bottom isn’t there! A quick message to the seller elicited the reply that it was a mod. requested by his late father and carried out by ‘John’ (presumably John Oliver) at the factory. He does not know the purpose of this modification.

    Do you have any idea why this fin removal work may have been performed? – I’m at a loss. I note also that the serial number on the mounting lug appears to be partially obliterated – stranger and stranger!
    I’m still happy with the engine despite paying quite a sum for it because it runs so well and shows no sign of overheating.

    All the best to you and thanks again for a wonderful site. I’ve just finished reading your glow plug piece – fantastic stuff. It explains a lot of things which I ‘half knew’. I used to fly F3A aerobatics and the best plug for my Yamada 61 with tuned pipe exhaust was always a OPS ‘Silver’. I knew they were v. cold cos they drew a current of over 5 amps!

    Anyway, if you could shed any light on the reason for my missing Tiger fins I’d be extremely grateful.



    1. My impression is that this is an original example. As you say, Woody’s replicas were all (as far as I know) numbered in a “Bxx” sequence. Moreover, I understand that only 50 or so were made. Therefore your number of 063 is beyond Woody’s sequence. I have no idea what the BC stands for – boat/car?!? If so, the engine was intended for boat or car use and would have originally had a flywheel.

      Since writing my article, I have acquired an original; Ball 60 in new unrun condition bearing the number 754. No letter prefix ……………..

      1. Thanks a lot for Your opinion, Adrian.

        According to its appearance, it really does not look like Bartlelts precise new reproduction, but it has such a patina and small bumpinesses, that it looks like an original. I will see, it has not arrived yet ….
        ( I will weight it , and afterit it will be clear …. )

        I am going to build it in a vintage plane “Spook (1940)” , I am looking forward to it …

        Have a nice day, Mirek

      2. P.S.: 754 … very, ver nice ! Congratulations !

        It looks like they stared the production ordering from the number 500 … 🙂

        The Ball is very nice and seems be practical in some restricted cases of engine placing.
        Dooling, McCoy, Baab-Fox have intake in the back, Bungay below, but it is long himself – only Ball (rom reachable engines to me now :-)) is narrow and has intake in forward.

        Baab Fox I am planning to Torpedo II – I have Baab Fox “B01” …

        Thanks a lot, Mirek

          1. I know, I have red Your article about the Baab-Fox carefully and thats the reason I fel in love with it ….! 🙂
            I like especially, how Baab and Fox were telling lies about its performance in their adds … it is so funny and touching …
            I will give it 12×6 prop, I hope It reachead 8000 and it will be enough ….

  51. Hello Adrian
    Have found your website interesting and informative – am one of the hard core keeping the art of diesel engine running from becoming a lost one here in Hawkes Bay, New Zealand.
    One note – you mention in your articles regarding lubrication for said diesels that medicinal grade castor oil is useless in this regard. You may be wrong there – the leaflet which PAW includes with their engines mentions “Medicinal Castor Oil”as an ingredient in their suggested fuel mixes, also I have used the medicinal “Castor Oil BP” in the fuel mixes for my own PAW 1cc and 1.5cc engines for years without apparent problems.

    1. Good to hear! My own attempts to use medicinal castor oil were a disaster, so I never went back. Perhaps I should try again! I’ve been using the 100% cold-pressed variety available from health food stores with complete satisfaction.

      There are always more complexities!



      1. Hello again Adrian
        Thanks for your reply – the medicinal “Castor Oil BP” turns out to be cheaper around here than the cold pressed health shop variety – I suspect they are adding a “healthy organic premium” to the price!
        You may be interested to know that my diesels (including a 3.2cc RC Sharma, bought after reading your review) run well with 100% biodiesel replacing the kerosene component of the fuel. The biodiesel is made locally from used cooking oil. Nice thing about using it (apart from the tiny environmental benefit!) is that there is very little exhaust odour on the engine afterward (none of that “burned diesel” smell).

        1. Not surprised that biodiesel works well – after all, it’s intended for full-sized diesels, thus having fairly similar combustion characteristics to kerosene. My problem is that I haven’t found a local source, otherwise I’d try it myself!

          Thanks for the comment! I should add that to my diesel fuel article.

          1. Thanks Adrian. Experimenting with the fuel is an interest of mine.
            In order to conserve ether (the most fiddly of the fuel components to obtain), I have found that putting in equal parts of kerosene and castor, then adding just enough ether to make them dissolve into each other, seems to work well. In colder weather, when the two components separate again, just add more ether until they redissolve. Self compensates for harder starting in cold.
            The only problem is that the method does not work for biodiesel mixtures, as biodiesel and castor do dissolve in each other without any ether. I have gone back to equal parts of everything for biodiesel-based fuel for my engines.

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    Here’s another Wotzit. A Polish home-build from the 1950’s. 15.9mm bore, 11.36mm stroke giving 2.25cc swept volume. I finished fitting the piston and tidied up a few details to get it running. It does, but hollow 4mm crankpin is likely to break, so was retired after a few easy runs.

  53. Hi Adrian,
    I have a question that you may be able to help me with. I have a new CS ED 3.46 Hunter. The rotary valve is too loose for my likings but I can’t work out how the pivot is fixed into the back plate. I don’t know if it’s riveted or whether it’s a press fit and I don’t want to damage anything. Have you any experience with these things or have you ever had one apart?
    Any advice would be appreciated.

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    I have had one of those engines apart, Hans, but it was quite a long time ago now. I know that I didn’t like the CS disc valve either, and I replaced it with an E.D 346 plastic disc which fitted perfectly and will be far more durable in service. I have a vague recollection that the disc valve mounting pin was pressed into the backplate, and I pressed it out after heating, using the same hole to mount the E.D. component (which has its own pin). As a precaution, I also heat-normalized the crankshaft, since CS shafts tend to be rather brittle. My engine runs superbly and has proved to be bulletproof.

  55. Thanks for that Adrian, much appreciated. At what temperature do you normalize your crankshafts please?

  56. The crankshaft normalization procedure involves putting the shaft in a cold domestic oven, heating said oven up to around 550 degrees Fahrenheit with the shaft inside, holding it there for about 2 hours and then switching it off and allowing it to cool slowly in its own time, again with the shaft remaining inside. Check with the missus before you try this one – ties up the old oven for a while!!

    The process does not guarantee the integrity of the shaft, but I have yet to have a failure of a normalized component.



  57. Hi Adrian,
    Thanks for 2.5R article, excellent.
    Bought my first Webra (at 14yo in NZ) in 1956, a 2.5R glow, later a 2.5R diesel also. Became an immediate fan. My experience slightly different in that the diesel had a squeaky tight piston whereas the glow not tight but had a perfect compression seal. The glow piston substantially lighter (thinner walled) and longer (no sub piston induction) whereas I’m sure the diesel had SPI.
    Also, thanks for high standard of photography, I save them all. Many visitors may not realize the image size although when using Firefox you can right click “View image” to see actual size.
    Cheers and thanks.

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    Dear Adrian,
    I just back home after two week holiday and I think you don’t receive my mail on wotizit mail adress, so I send it again on the blog.

    When I read about the wotzit engine that it was probably a French engine, I was sure that it was a wrong way. For me the right way was Indian. When you confirm the MODELSPORT origin, I decided to do some search. It was long but I found. The engine is a KUMAH AM 25 who produce also the KUMACH K75 an Indian version of MILLS 75. I found these informations in AERO MODELLER of September 1975.
    You can read here a short story of MODELSPORT that I write.

    If you give me an anther adress, I mail to you a scan of the magazine


  59. HI Adrian,
    What would you recommend for making a main bearing for a spark ignition O&R 60 engine? Would you use phosphor bronze?

    1. A phosphor bronze bearing with a steel shaft will outlast the rest of the engine if properly fitted initially. I’d say go for it!!



  60. Hello Adrian
    Have you heard any reports about the “ED By West” diesels being offered by Weston UK?
    Appear to be a hybrid of ED parts with their West high performance glow engines. Look attractive on their website but would be interested in how they actually run.

  61. The West engines originate with Alan Greenfield’s Weston UK business. The West glow engines are based upon latter-day Webra models – when Webra was wound up, Alan bought the dies and tooling. They also offer a few models of the “original” E.D. engines – I have a couple of their air-cooled E.D. Super Hunter units which run very well. A test will be forthcoming on my website.

    The “E.D. by West” engines are diesel conversions of the earlier Webra-based glow units. I have no information on how they run, but knowing Alan Greenfield as I do I would expect them to perform pretty well.

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