Engine Doctor
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Posts posted by Engine Doctor
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Just change the socket to match the Futaba plug. Far easier , cheaper and more reliable than using an adaptor on an old socket .Also check the associated wiring as if the socket is corroded its likely that corrosion will have crept up the wiring . Just had to do a similar job on a car door plug and socket with 17 wires. Plug and socket unavailable without buying the loom costing £100's . Fixed using hollowed out original plug and socket with ñew pin and socket connectors fitted . Cost a couple of £'s.
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13 hours ago, Jim Hearnden 1 said:
A 10 or 11" prop would be ideal. It needs to be quite weighty as it'll need some flywheel effect. The one I had was fitted with a home made wooden prop. It ran pretty well, dead easy to start.
Hi Jim . I have to disagree with you on using a large prop on a small diesel. The leverage from a large heavy prop can and will severly damage a small diesel if it hydraulic locks. Ive seen bent rods broken cranks,split pistons and even broken crank cases all from doing just that.
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14 hours ago, John Tee said:
I've got a sore finger from trying to start the .75 DC Merlin when it hydauliced and my finger slid along the prop leaving a minute cut. I will bear in mind your advice and put a glove on. Are there modellers/traders who trade spares for older engines or is it just keep looking on Ebay? I was looking on the website of a well known model shop and the smaller size props 7 - 9 inch seem to be a rarity these days. Plenty of 12 - 24 inch props in IC and electric. I haven't got any smaller ones in my box of props at the moment but I used to have a lot. It would appear the demand is for bigger petrol engine sized props or electric.
Just keep looking on Ebay for r hine spares. Often an engine ideal for spares will come up. You can always ask on here . Ive been helped out a few times for bits. Are you looking for any parts at the moment ? There used to be a few dealers in old spares but they come and go. Things like needle vakve asemblies and piston rings are readily availabke from a few dealers. Other bits like cranks or cases are now mainly from a breaker engine . Pistons / rebores can be made and a few poeple do this. Judt adk around at a club or on here. The swap meet at Old Warden can be a hold mibe fir engine parts.
Yes small props are getting rarer but visit any swapmeets etc . Often find loads of props for very little money but beware of chipped props and nylon props should be left in a pan of near boiling water for a few hours as they dry out and can be brittle.
Re the sharp props . Always always sand off the sharp flashing and re- balance props before using. Nothing worse than slicing your finger along a prop on cold day and getting diesel fuel in it ! Child hood memories are very vivid about that.
Good luck and keep the diesel revival going
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Most of the ED Mk2 or comp specials only had to get a whiff of ether and they would fire . Dont get caught out , only 2cc but can still give a hefty whack on the fingers😖. Lovely old engines and worth getting a proper prop driver .
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25 minutes ago, EvilC57 said:
Joining wings where there's a large epoxy joint is my problem. Beasuse I know there's only one chance to get it right before the epoxy goes off. I'm always careful to get everything ready, and pre-check alignments, availability of tools, clean up tissue, solvent etc.. But I always have a fear that as soon as I've mixed up the large amount of epoxy required there'll be someone at the front door, or the phone will ring!
Thats simple . Turn phone off, , lock yourself in workshop, use slower setting epoxy with decent clamps qnd let the world do one until your ready 😉. If its important any caller will call back or leave your answerphone on, oh and switch off the devils invention... the mobile.
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Funny how times change . FrSky started off making clone rx's to use with Futaba , JR etc. When other companies started cloning their stuff they didn't like it and changed protocol to stop them I believe. Still excellent gear though.
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4 minutes ago, Cuban8 said:
Interesting stuff. Not essential to know the ins and outs, but all part of the pleasure of the hobby.
Wasn't aware that Zenoah sparkies had no advance and retard - rather like my lawn mower I guess - all a compromise to keep it simple.
As you say a compromise hence the lower power than the electrnic ign models. The timing was also set at a compromise for srarting and best running. Very simple the mag models but you paid the price in weight and a heavy flywheel .
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2 hours ago, Paul De Tourtoulon said:
I was told it was 'pinking',
Diesel Injectors, if my memory is right, were regulated as far as 230 bars on the 6 cylinder Volvo engines.
Hi paul . Yes pinking thats what i said. Its nothing to do with injectors but compression and burn speed of the fuel being used in the cylinder.
As for how our glow engine ignition works i can only give my practical or real world opinion as I have no degree and im not into the theory side of things.
If you run an engine where you can see inti the exhaust port , something like a cox 049 you can see the reflection of the glow plug. As you increase speed you can see the gp coil gets much brighter/ hotter . Connect a battery and it will glow almost white hot. Its the extra heat causing a quicker reaction with the fuel and platinum coil that advances the ignition process. The ignition ofmethanol is partly heat and partly due to a catalytic reaction with platinum and as we all learnt ar school heat speeds up these reactions.
Diesel engines or compression ignition work similarly but with a much higher compression ratio typically 16:1 or higher. The faster the engine revs the hotter the cylinder gets so advancing the ignition point /timing. If our model diesels get too hot they over compress and will eventually stop. You may also have noticed if a vintage model when a diesel starts to over compress they eiund heavy and laboured. A long shallow dive often cools it enough to run well again and even induce a occasional misfire or under compression as timing is retarded again.
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The majority of small petrol engines , 10 to 15 are JMO a waste of time. At 20cc they start to become useable but weight often make them a poor choice. The DLE 20 though is a good lively chiice although you still have to factor in the weight of a proper exhaust and ignition system , battery etc. Most other designs dont come into their own until they exceed 30+ cc. And 50cc is where they really become a good alternative to glow....but a decent exhsust will often cost as much as the engine. The supplied exhaust deflectors as a waste of time and a cause of many site problems .
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Very simply ,your engine looses a few revs as the glow plug cools slightly without the electrical current to heat the coil. This efectively retards the timing slightly. As already said other factor all play a roll in the timing of a glow engines. If glow plugs are very old this slowing can be more noticeable. For the same reason you should never run a glow engine at full thtottle with the glow swithched on as this can cause pre ignition or knock and damage the engine resulting in extreme cases with a hole in the piston crown. Prop throwing is a prime example of over advanced ignition often caused by a weak mixture at full throttle. This knock will also shorten the plug life. Modern designs have to a greater degree engineered out this extreme knock. Assuming mixture is correct then its perfectly normal. If the coil in your engines glowplug looks white an crystally instead of silver then its getting past it. If engine still runs reliably apart from that then just fly it.
Us oldies will remember when fiddling with our cars that if the timing was set wrong we heard a tingling sound , a bit like the sound made when tapping the bottom of a cup with a pencil . This only occured when engine is under load as when accelerating , its called pinking. Also heard is a lower octane fuel than the engine was designed for was used.
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I used to buy my batteries from 7dayshop.com but when Covid struck the supply chain fell down and they no longer list them. I still hsve some left so ok for a while. I have some of their AA cells made into Tx pack probably 8 or nine years old and some AAA packs in models a few years old and working fine giving good voltage etc under load . Never been a fan of Vapextech cells . I bought some when they first appeared and they didnt last very well. What to use when my stock is used up ?
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With Nimh cells i have found that anything above 2000mah capacity are more prone to failure and drop their voltage drastically under load as IR increases. I lost a good model sone time ago when a cell in a 6v 2700mah pack packed up. When checked the pack showed 6.3 v but as soon as any load was put on it the voltage dropped to zero ! Just one cell cost a lot of grief .Up to 2000 mah they seem fine. I now only use the ready charged or LSD type as they seem even more robust than the standard type.
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2 hours ago, 911hillclimber said:
After I get it running I will clean and paint ready for display!
Just realised that I have not finished the wrist pin. I have to add the brass pads on each end, so that fiddly job to do while i await the cylinder nuts AND the 1/2 litre of diesel fuel off ebay.
Local model shop cannot supply diesel or glow fuel now!
£23 for the fuel!!
Southern model craft used to sell a ltr for less than that ! Luckily i stocked before Dave retired. The new owners have gone quiet but were supposed to be keeping the name going. Fingers crossed.
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2 hours ago, Paul De Tourtoulon said:
Yes, but without it, I will be going back to change the bearings on my 4 strokes every 2 years. 😡
Every two years ? Really. I ran a Saito 45 for five years on one set and a ys 63 for longer with no bproblems . All my fuel is synthetic based , never use castor except in old engines and diesels with iron pistons / liners.
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Look for Sellotape Diamond tape if you can find any otherwise their Superclear tape 8s the currdnt nearest. Very strong adhesive, UV resistant and once on its unoticable as its so clear. The Scotch tape super clear is not very good.
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All goo
16 minutes ago, Paul De Tourtoulon said:Another 'tip' on 4 strokes is to leave the engine on its compression stroke, so that you don't end up with the valves sticking open.
Good tips add up and " Many an ickle makes a muckle"
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Once your happy with running the engine and want to add colour to the cylinder fins have try at Anodising. Pic below is a crankcase I made for my Boddo Mills. If you fo try anodising then start with blue or red dyes as greens yellows are notoriously tricky to get right.
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Hi Andy. Welcome back to the world of IC power. Dont turn down a Enya 4C if one turns up. They are in the same class as Saito and OS for quality of materials and reliability. Spares may be an issue now but generally they last and last and are very strong. You could also consider a smaller laser . Jon knows everything there is to know about them and can advise.
Re laying up for winter . Corrosion will be your enemy. On the last run of the year, run the engine out of fuel while its GOOD AND HOT after flight and make sure its not running rich . Doing this will help evaporate any methanol thats got into the crankcase . Then as soon as you can give the engine a good dose of oil. In the cylinder, through the crankcase breather and inside the tappet cover etc. Dont use any fuel or oil that contains castor oil or 3in1 oil as it set like varnish . Over the years ive tried many different oils for storage and found air tool oil to be very good for this as its designed to protect air tools from any moisture in the air that powers them.
Any used engine can be a risk . With four strokes beware of any of the chinese clones that have little or no compression. Check this with a fully open throttle; very low or non existant compression idicates a manufacturing defect and is only fixable by fitting a new head. Also check the thread where the exhuast fits into the head . This applies to any engine with a screw in exhaust. A worn thread means a new cyl head ! Look for any nuts that have been chewed with pliers or wrong size spanners a sign of a careless owner. Lastly remove the glowplug and check thread is ok. I was caught out by that many years ago with an open rocker Enya I bought that had the glowplug glued in !
Spares like castings and specialised parts for all Chinese clones are virtually imposible to find new and parts for current OS or Saito or YS engines are very expensive.
Bearings if a bit loose or noisy are easily available for virtually any fs engine and not expensive and available from any good bearing supplier.
Never be afraid of asking about engines on this forum , no question is a silly question . If your a member of a club beware of unsolisited help from the " Club Expert " look for any advice needed from an IC flyer who doesnt constantly fiddle with his engine and has consistent flights .
Good luck and enjoy the sound
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Hi EGB. The weston silencers or pipes are tuned for outright performance or throttle responce and are verh good . Your os silencer mising part is likely the same size as those fitted to many chinese clones like ASP, SC etc. There are loads about secondhand have alook on ebay and check mounting hole centers. Also measure the inside diameter of the exhaust you have and you may
a used end cone and through bolt on here .
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35 minutes ago, chris collis said:
On reflection of all the various advice and thoughts given, I think I am going to go down the road of discharging with a headlight bulb and disposing safely at the local recycling tip.don’t want to be responsible for any lithium fires! I have seen the videos for batteries catching fire in aircraft at flying fields!Just as an aside, I wonder how spent lithium batteries are going to be dealt with in electric vehicles when they come to the end of their lives?
Any car bulb 12 or 24 will do doesnt have to be a headlamp bulb . Indicator bulbs work fine and we usually have those lying around .
I used to just dunk them into a bucket of salty water overnight but was told that it leaches lithium into the water and that has its own issues with disposal; but it does completely discharge them .
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20 minutes ago, Engine Doctor said:
If your crank case is not square suggest re facing the surface and then cut a shim for base to correct the height of cylinder. If case is ok check cylinder base for square.
Another possibility is that the bores in the conrod are not parallel. This can easily be checked by fitting a drill shank or some metal rod of appropriate size in both the big and little end journals and check for parallel. Easier to check this first .
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If your crank case is not square suggest re facing the surface and then cut a shim for base to correct the height of cylinder. If case is ok check cylinder base for square.
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I have just looked at the Spectre 1950 engine test for the DC Wildcat , a 5cc longstroke engine , not unlike your engine. The test was done by L. H. Sparey for Aeromodeller in the April 1950 edition.
The recommended prop for that is 13 x 6 . It might spin a 15 x 6 when its run in but its a bit of an ask and unlikely to be of any real advantage for thrust .
As Jon says start off with a lighter load . Once running and up to temp stop it and allow to cool a few times. If at any time it starts to overheat and labour stop it and allow it to cooI completely then start again .It should start to loosen up after a few stop start cycles. Gradually increase speed and adjust comp and fuel for max revs. Once it can hold its rpm without overheating or labouring then try experimenting with props. The Wildcat tested said that it would spin a 13 x6 at between 9k an 10 k rpm but that was a Mk 3 so DC had done some homework to get there.
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Hi Rich . Dont forget to allow extra time for delivery as 20 mph will slow the post van 😉