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ST G20 15D
I've had a G20 for a while that had a new piston made for it.
I ran it once, was unimpressed & put it in the "one day" pile. Well today was the day. I put on a 7X6 and fueled it up. It gave a couple of sharp barks but didn't seem too keen to keep on running. So I switched up to an 8X6 and we were soon making really encouraging noises. At last after a few muttered incantations, it gave a good little run, but soon slowed down & stopped. So I realised it was still too fresh to run that much comp, and for that long. After a couple of short runs on low comp, and allowing a good cool down period. It now starts fairly easily, but still hasn't built up a good piston seal. So it looks like its going to need a fair bit of running before it can get into the air. But I'm a lot happier knowing it's a going concern Greg |
RE: ST G20 15D
Duplicate post!
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RE: ST G20 15D
ORIGINAL: greggles47 I've had a G20 for a while that had a new piston made for it. I ran it once, was unimpressed & put it in the ''one day'' pile. Well today was the day. I put on a 7X6 and fueled it up. It gave a couple of sharp barks but didn't seem too keen to keep on running. So I switched up to an 8X6 and we were soon making really encouraging noises. At last after a few muttered incantations, it gave a good little run, but soon slowed down & stopped. So I realised it was still too fresh to run that much comp, and for that long. After a couple of short runs on low comp, and allowing a good cool down period. It now starts fairly easily, but still hasn't built up a good piston seal. So it looks like its going to need a fair bit of running before it can get into the air. But I'm a lot happier knowing it's a going concern Greg Greg, I'm a gessin that that's the one with the piston made out of 100 y/o cast iron. It comes out of 100 y/o timber window frames. They're from the cast iron counterweights that the rope connects to so when you open them they stay in the same position you left them. It's good stuff and all you need to do is keep running it like you have been. As the Arch-Bishop said to the Actress, have patience and it'll all be ok, . :D |
RE: ST G20 15D
ORIGINAL: qazimoto Greg, I'm a gessin that that's the one with the piston made out of 100 y/o cast iron. It comes out of 100 y/o timber window frames. They're from the cast iron counterweights that the rope connects to so when you open them they stay in the same position you left them. It's good stuff and all you need to do is keep running it like you have been. As the Arch-Bishop said to the Actress, have patience and it'll all be ok, . :D That's the one. Patience hmm..... any idea of a supplier? Not much of that round here.[&o] It sounds very spectacular in the back yard even on an 8X6. I'm guessing once it's run in it'll be a good performer. |
RE: ST G20 15D
Reading the review, ST G20-15D peaks at 15,000. I've been running 8x4 in OTS releasing at @14,000. Seems to be the happiest prop for engine. I've also run 9x4 at 12,000, which is OK but I like the 8x4 better. On the 9x4 there is a very noticeable pick up in RPM on release.
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RE: ST G20 15D
More running today - lucky the neighbours on both sides are away for Easter.
Still running rich & undercomped on 8X6. Tested at 12300. Starting to sound freer, but still no good amount of compression. Run run run! Greg |
RE: ST G20 15D
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ORIGINAL: greggles47 More running today - lucky the neighbours on both sides are away for Easter. Still running rich & undercomped on 8X6. Tested at 12300. Starting to sound freer, but still no good amount of compression. Run run run! Greg If you give it to me I'll pass it on. We ran a clubmates cheap but cheerful high performance European diesel in one of my DGYs yesterday. It stopped suddenly and spat the prop and spinner nut into the long grass. The pics below show the cause. It was doing about 25/10. Ray http://images.rcuniverse.com/forum/u...40/Sq46644.jpg http://images.rcuniverse.com/forum/u...40/Bw72490.jpg http://images.rcuniverse.com/forum/u...40/Wu61958.jpg |
RE: ST G20 15D
Well from the pix looks like the crankcase suffered no damage?? martin
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RE: ST G20 15D
ORIGINAL: AMB Well from the pix looks like the crankcase suffered no damage?? martin :D |
RE: ST G20 15D
I would suspect a "bad piece" of steel, maybe crystalized or soft in one spot , if it were say in the counterweight it would be a non issue it was just in the wrong place martin
even if the shaft was heat treated it still would have happened |
RE: ST G20 15D
That looks like it's a pressed in crankpin Ray?
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RE: ST G20 15D
good observation it does not look broken you can see the diameter difference on the pin martin
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RE: ST G20 15D
The first pic looks like the big end broke off the rod. Then the crank pin came out of the crank.
Did the big end bearing fail? and then the crank pin dislodged? or was it a simpler case of the crank pin coming loose? Either way I'm sure you'll have it back circulating again quickly. Greg |
RE: ST G20 15D
ORIGINAL: raglafart That looks like it's a pressed in crankpin Ray? It can be pressed back in with some loctite added. There seems to be a few from the first batch with the same problem Ray |
RE: ST G20 15D
Ah the miracle of locktite J and B weld would not cut it it would be wiped off when you stuck it in martin
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RE: ST G20 15D
Or did the pin/rod seize from too little clearance, twist off the pin and snap the rod?
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RE: ST G20 15D
Back on topic - Taking full advantage of the neighbours absence today and more running for the ST.
The comp is coming in very slowly - It's now had about a half a litre through it. Maximum run at any one time is about 2 minutes. More of the same needed. Ray are you able to source spares? G |
RE: ST G20 15D
ORIGINAL: greggles47 Back on topic - Taking full advantage of the neighbours absence today and more running for the ST. The comp is coming in very slowly - It's now had about a half a litre through it. Maximum run at any one time is about 2 minutes. More of the same needed. Ray are you able to source spares? G See email. Ray |
RE: ST G20 15D
ORIGINAL: qazimoto I'm a gessin that that's the one with the piston made out of 100 y/o cast iron. It comes out of 100 y/o timber window frames. They're from the cast iron counterweights that the rope connects to so when you open them they stay in the same position you left them. It's good stuff and all you need to do is keep running it like you have been. :D (I think that this has been covered before but) why would 100 year old cast iron be classed as 'good stuff' when it was originally tasked for the lowly job of being a 'weight?' Usually the unspecified dross from the furnace makes its way into such non structural things. Has it been chanced upon as being good? Thanks. |
RE: ST G20 15D
Old cast iron that has not been used or in a stressfull application has been normalised by nature , its been through many daytime heating and nightime cooling cycles. This reduces the internal stress's and heals microcracking from the casting process - this makes it desirable for engine use, provideing the cast iron is of suitable quality in the first place. A tidbit of history, Roll's Royce discovered that engine blocks,crankshaft and piston castings that were left outside in the weather for a year or more befor machineing produced more reliable engines, this was one of there secrets to success in there early days.
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RE: ST G20 15D
I think back when ford or GM did the same thing they would just sit outside in the weather for a year or so probably fill up an acre martin
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RE: ST G20 15D
On my way to school in the UK I used to pass Colchester Lathe on the bus back in the 50's and 60's. They had a field full of lathe beds. Rusty big lumps of cast iron. These were left there for some 5 or 6 years from memory to age. Something that most quality machine tool factories did in the day. In winter they would be covered in snow and ice and of course in summer drenched ( :D ) in sun.
They had to plan production of their machines well in advance. Not sure if it's done these days. Just tried looking for the Colchester Lathe plant in Colchester on Google maps but it's been moved to Yorkshire so who knows!? |
RE: ST G20 15D
ORIGINAL: Recycled Flyer ORIGINAL: qazimoto I'm a gessin that that's the one with the piston made out of 100 y/o cast iron. It comes out of 100 y/o timber window frames. They're from the cast iron counterweights that the rope connects to so when you open them they stay in the same position you left them. It's good stuff and all you need to do is keep running it like you have been. :D (I think that this has been covered before but) why would 100 year old cast iron be classed as 'good stuff' when it was originally tasked for the lowly job of being a 'weight?' Usually the unspecified dross from the furnace makes its way into such non structural things. Has it been chanced upon as being good? Thanks. While it's difficult to determine the foundry practices of 100 years ago, I'd guess that each one would have had some steel molds which would have been the recipient of whatever cast iron melt was left over from the days pour. Window weights would have been an ideal product for this excess material. Leastwise that's how I would have organized things. The stuff has a fine grain and turns nicely. It wouldn't have these properties if it wasn't a high grade cast iron. Ray |
RE: ST G20 15D
I haven't been able to give it a run over the last couple of days. But I believe that the piston is still growing as a result of the heat cycles the run in process gives.
It's taking a fair bit of running to do so, but the longest run so far is just a tick over 2 minutes. Rome wasn't built in a day. G |
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