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Rivers 2.49cc and DC 1cc engines

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Circlip	19/04/2010 12:52:14
1723 forum posts	Already mentioned on Ramons "Racer" thread, the nylon prop will have "Dried out". Any "Old" ones boil in water for quarter of an hour and leave to cool submerged in the pan. Regards Ian Providing you don't sharpen them, wooden props ALWAYS left a better cut.
Terryd	19/04/2010 17:38:23
1946 forum posts 179 photos	Cheers Guys, I got your message at work Ramon and settled for a new nylon 9 x 4 prop as they didn't have that size in wood. I have a couple of smaller nylon props for the DC Ian, and I'll try boiling those to see the effect. While in the shop I noticed a cabinet with vintage motors which the owner called his Archive. There were some beautiful motors including another Rivers but with a different pattern crankcase but the same Cylinder head as mine. There were too many others to take in in one go but the owner said that most of them were loaned by customers. I hope to persuade the owner to let me photograph the engines (through the glass cabinet probably) and if I can I will post some pictures. Thanks again for the advice I'll keep trying, but not this evening, I've had a hard time trying to teach 13 year olds all day while being disrupted by room changes as my IT lab was being used for exams. It's 12 year olds all day tomorrow under the same circumstances Regards Terry Edited By Terryd on 19/04/2010 17:39:01
Ramon Wilson	19/04/2010 18:45:10
1655 forum posts 617 photos	Hi Terry, Have a look at this - http://www.go-cl.se/trh/rivsilst.html it might explain the difference. Did the shop have any fuel by any chance? Keep at it - Ramon
Terryd	19/04/2010 21:16:18
1946 forum posts 179 photos	Hi Ramon, The Rivers in the shop had a completely different crankcase from the ones I am used to. I will try to get a pictuer soon and you will see what I mean, Perhaps it was a larger capacity, I'm not sure. Unfortunately he had no fuel as he said most of his customers were into electric motors these days. Not quite the same romance unfortunately as far as I am concerned. I love the sound and smell of these old engines. A bit like the sound of vintage British motorbikes perhaps? Perhaps I'm too old fashioned now!! So it looks as if I will have to mix my own fuel for small quantities in future until i can get to a show. Best regards Terry p.s. wonderful pictures of the Rivers by the way. T
Ramon Wilson	19/04/2010 22:55:45
1655 forum posts 617 photos	Hi Terry, That figures on the fuel - it's the way things seem to be going for most of the hobbies that require power units. Understandable really - far less mess, clean (no oil!), quiet-ish and awesome power output but as you so rightly note no smell and 'noise' (and short endurance to boot). It's a real sense of the times when the only engines in a model shop cabinet are for nostalgia display only! A couple of years back I was asked to sell a small collection of marine (model) engines for someone who had died. Most of these were new in box so I bought two model boat magazines to get some idea of current pricesand there was not one listing for an IC engine in either It's possible the other Rivers in the shop is the 3.5 Silver Arrow. Similar in layout but a beefier crankcase with possibly a longer intake tube than the Streak. Heres another site - scroll down to the bottom, there is a Silver Arrow second row up. http://www.sam122.sk/engines/other/other.htm Some lovely engines on here, real 'objets-drool'. Offer is still there if you need the improver. PM me your address when you're ready Jens my aplogies for not reponding to your last post. I have the Moulton book - thanks. I too have used various oils both castor and mineral for diesel fuels but that was a few years back. If I ever do mix any fuel again I will keep in mind the MEKP and see how it compares. Thanks again - Ramon
Ramon Wilson	19/04/2010 22:59:02
1655 forum posts 617 photos	Hi Terry, That figures on the fuel - it's the way things seem to be going for most of the hobbies that require power units. Understandable really - far less mess, clean (no oil!), quiet-ish and awesome power output but as you so rightly note no smell and 'noise' (and short endurance to boot). It's a real sense of the times when the only engines in a model shop cabinet are for nostalgia display only! A couple of years back I was asked to sell a small collection of marine (model) engines for someone who had died. Most of these were new in box so I bought two model boat magazines to get some idea of current pricesand there was not one listing for an IC engine in either It's possible the other Rivers in the shop is the 3.5 Silver Arrow. Similar in layout but a beefier crankcase with possibly a longer intake tube than the Streak. Heres another site - scroll down to the bottom, there is a Silver Arrow second row up. http://www.sam122.sk/engines/other/other.htm Some lovely engines on here, real 'objets-drool'. Offer is still there if you need the improver. PM me your address when you're ready Jens my aplogies for not reponding to your last post. I have the Moulton book - thanks. I too have used various oils both castor and mineral for diesel fuels but that was a few years back. If I ever do mix any fuel again I will keep in mind the MEKP and see how it compares. Thanks again - Ramon
Terryd	20/04/2010 16:27:47
1946 forum posts 179 photos	Hi Guys, Just to report a small success. I have managed to get the Rivers firing but not running. It did run once for a couple of seconds (at most) when I choked it with my left hand as advised. However following that, the engine fired once and then caught my finger, cutting it in the process! So now I must look out my old finger protector which I used to use. I'd forgotten how vicious these little things can be. I'm sure it won't be long before I have success. I'll keep you posted. Terry
Circlip	20/04/2010 19:05:28
1723 forum posts	So now I must look out my old finger protector which I used to use. I'd forgotten how vicious these little things can be. Damned wimp, it's nobut a 249, Flicking an OS 40 glow makes you quicker Regards Ian.
Ramon Wilson	20/04/2010 19:51:58
1655 forum posts 617 photos	Hi Terry, Welcome to the club! Take no notice of 'old show off' (TiC) above - those diesels can give you quite a nip ha ha - my first cut came from an even 'whimpier' AM10 - first engine. It was running backwards so I put my left hand behind the prop to put my finger over the intake to stop it and the Frog 7x4 nylon 'razor blade' cut into the side of my fore finger for near its length. Quite a baptism for a 13 year old! and the scar is still to be seen when my hands are cold - happy days. Big or small though they all bite it's just some bite more than others but I would agree the bigger they are the more they can hurt ! Going back to your cut If the nylon prop you bought was a 'glass filled' type - Graupner, Master, APC (particularly APC!) etc then its a good idea to take a bit of wet and dry and sand off the flashing down the edges of the blades as these can be very sharp and can give a really nasty cut especially if, when against over compression/flooding your finger is forced to run down the prop blade. - Don't ask That won't affect the prop in any way for your current needs. Glass filled props are normally opaque and more rigid than the type you broke. I've had a good day today - been over to my friend Lee's and used his bead blaster. The Racers and a couple of other rebuilds are now looking much nicer. Keep the elastoplast handy Regards - Ramon PS If you have got it firing as you say you are not far off the settings - don't be tempted to increase the compression too much at this stage but let it fire and run like that a few times - the length of these short runs should gradually increase . If it does break into a run but is a bit intermittent then increase the comp a bit but if all you can get is just short bursts then open the needle slightly and increase the comp a tad. Edited By Ramon Wilson on 20/04/2010 20:00:37
Terryd	20/04/2010 21:22:55
1946 forum posts 179 photos	Thanks for the belly laugh Ian, it was really welcome. It's a good job I was using my right index finger at the time, I didn't feel it too badly as the nerve endings have never grown back following the end being sewn back on after the bandsaw incident. But that's another story. Also thanks for the encouragement Ramon, I appreciate the contributions from both of you!! With such support and advice, how can I fail Best regards Terry
Jens Eirik Skogstad	20/04/2010 21:59:04
400 forum posts 22 photos	Posted by Ramon Wilson on 19/04/2010 10:25:20: Jens advice on establishing the starting position may prove problematic if the contra piston is very tight in the bore. Screwing right down over compresses the engine and it could (not will) lead to damage to the con rod. Regards - Ramon Check first the contrapiston are not stuck in the sleeve before resetting the start point before starting the engine. How to resetting the compression ratio before starting the engine: To example the screw are 6mm with treads 1 mm or cylinder head gasket at 1 mm thick, and the cylinder volume are at 2.49ccm. You want to set 16:1 compression ratio as start point. How to find: To calculate all volume i am using centimetre instead millimetre and it is easier... Bore: 1.475 cm ,stroke: 1.457cm = 2.49 ccm The contrapiston has diameter 1.475 cm and stroke are variable with compression screw or in case fixed compression adjusted by cylinder head gasket. To example we set 1 turns with compression screw and the screw are moving up 0.1 cm cause treads are 0.1 cm (M6x1 metric screw) or use cylinder gasket in 0.1 cm thick washer (gasket) instead compression screw to example in fixed compression diesel engines. Now we calculating headvolume: 1.475 cm:2=0.7375 , then calculate volume 0.7375mm x 0.7375mm x 3.14 x 0.1cm = 0.17 ccm 2.49ccm + 0.17 ccm : 0.17 ccm = 15.64:1 Compression ratio It is near to 16:1 in compression ratio , now you are ready to starting the engine.. Depent on fuel mix the compression ratio can be between 15:1 and 18:1 as start point before fine adjusting the compression setting while the engine are running. Some model diesel engine has a stop pin mounted at cylinder head where the compression screw has a limited rotating until a turns, this is ready calculated to adjust compression ratio from lowest to highest level. Edited By Jens Eirik Skogstad on 20/04/2010 22:00:15
Ramon Wilson	20/04/2010 22:36:19
1655 forum posts 617 photos	Thanks for your info Jens. I do find this interesting that you do this as I have never ever given a thought to the mathmatics of compression. As I'm sure you are aware compression varies depending on load as well as fuel and of course ambient temperature too. I confess my knowledge is purely practical having run them for many years and the technical side has never been a concern - all have their individual characteristics though - some start and run so readily whilst others can be so obstinate at times. I mainly used diesels with the odd glow - Mercos mainly - until I began to take an interest in control line aerobatics in the eighties when I began using glow motors in earnest. Apart from a very short period into some very low key team racing the diesels have always been used for sport flying. I do not 'collect' engines but I do think they collect me! I've always had a passion for them since that first one at age thirteen but most of them have been very much 'come and go' over the years. It never fails to amaze my long suffering wife how they seem to accumulate so rapidly though the current 'stock' is well down on what it used to be. I had a good clear out at the last Watford 'Swapmeet' and sold all I took bar two. Funnily enough Ian they were OS 40s - I still have 'em. Apologies - going off topic, Thanks agin Jens regards for now - Ramon

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