Bob, I think GH is probably right.
You're talking engineering principles, which no-one disputes.
My point is that one-one ever bought a bad new ED, Oliver, Rivers, Eta, ST 15D, Enya 15D, Micron, Drone, Owat, Taplin Twin or Mills .75 or 1.3, etc.
However, nowadays, we're constantly hearing stories like fiery's, where an engine just can't be hand started... Why?
It never happened with the engines mentioned above...
I'm pretty sure that the reason is the one I stated, although as GH says, it's probably down to cultural/operating errors. I'll agree with that, but the end result is still ****!
A few weeks ago, I was in contact with a well-known American SAMer, who was selling his CS ED Hunter because he couldn't start it... It never happened with the originals!
Only last week, Jon Fletcher posted on a forum to the effect that the CS Tiger generally needs "rebuilding" and that it would be a better bet to restore an original.
I've also seen Elfins heavily criticised on the SAM US forum... except that the guys usually forget that they aren't referring to real Elfins! (fiery's problem).
On a more personal note, my judgement is based on 62 years of diesel operation, 49 years of collecting, and a love of the older model diesels. When I see diesels discussed on the various forums (converted glows, Davis heads, engines like fiery's), I'm left with the impression that we just ain't talking about the same animal.
As an illustration, here's the earliest ED 3.46 that I'm aware of. It's unmarked, except for the S/N indicating engine N° 1 in August 1949, two months before they were released - Beautiful! and a super runner... Bob, stop telling me that CS are made on CNC machines, just consider the product...

CNC has very little to do with model engine cylinders. CNC is just a tool. The fine fits require know how.

I've never seen a bore taper published for a reliable model diesel. I suppose it's easy enough to measure, but I haven't measured a diesel. Materials come into play as well. Modern is one thing, but comparing something like current F2C engines to CS and grouping them together as "modern" is simply wrong.

I've never had any problems hand starting a glow to diesel conversion. Heck, I run ringed diesels and they hand start. But, I also have engines like the MDS 1.5 tether car diesel that was so poorly built the cylinder head didn't seal as supplied, and then broke a wrist pin when that was remedied. One day, I will piece together a running engine from the 3 I have and my own parts.

Like anything else there is quality and there is product made to look like it works. Unfortunately, you can't tell until you attempt to use it.

I have this thing about how people compare the current world to how it "used to be". Th truth is the world is virtually the same with respect to people. People make the decisions about the way things are. If they want to make a world class engine, they will do so. If they need to unload scrap metal at retail engine prices they will do so. How many low quality diesels were produced 50-60 years ago? I only know of a few names, but you guys know which ones I'm talking about, Gotham Deezil, etc. Is that really any different today?

Greg

Originally Posted by brokenenglish

My point is that one-one ever bought a bad new ED,

Brian, I have to say that I agree pretty much with all you say, and would certainly defer to your vastly greater experience of diesels than mine on the rest....apart from the above. After being very happy with my E.D. Bees I made the mistake when I wanted a 1.5 of buying an E.D. Hornet. What a God-awful engine that was! EVERYONE in my club had a go at it and it simply would not start. (Starters being unheard of in those days we couldn't try one of them) Eventually I part exchanged it for a lovely Frog 150 and life turned beautiful again. So there was at least one diesel from the old days that was an absolute dog, and I had it. E.D. obviously did learn how to make a 1.5 as I later had a Super Fury which was superb.

George, I often think that if I didn't have my engine collection, I'd fly electric and 4 strokes, but I've been hoarding them all these years for my old age, so I ain't gonna change now, unless its just to learn to fly (on an RTF).

Originally Posted by brokenenglish

"My point is that no-one ever bought a bad new ED, Oliver, Rivers, Eta, ST 15D, Enya 15D, Micron, Drone, Owat, Taplin Twin or Mills .75 or 1.3, etc. However, nowadays, we're constantly hearing stories like fiery's, where an engine just can't be hand started... Why?
It never happened with the engines mentioned above..."

The following excerpt is from Monty Tyrrell's article "Fifty Years On" which appeared in the 1991 edition of "Aeromodelling Digest"

Originally Posted by gkamysz

CNC has very little to do with model engine cylinders. CNC is just a tool. The fine fits require know how.

I've never seen a bore taper published for a reliable model diesel. I suppose it's easy enough to measure, but I haven't measured a diesel. Materials come into play as well. Modern is one thing, but comparing something like current F2C engines to CS and grouping them together as "modern" is simply wrong.

I've never had any problems hand starting a glow to diesel conversion. Heck, I run ringed diesels and they hand start. But, I also have engines like the MDS 1.5 tether car diesel that was so poorly built the cylinder head didn't seal as supplied, and then broke a wrist pin when that was remedied. One day, I will piece together a running engine from the 3 I have and my own parts.

Like anything else there is quality and there is product made to look like it works. Unfortunately, you can't tell until you attempt to use it.

I have this thing about how people compare the current world to how it "used to be". Th truth is the world is virtually the same with respect to people. People make the decisions about the way things are. If they want to make a world class engine, they will do so. If they need to unload scrap metal at retail engine prices they will do so. How many low quality diesels were produced 50-60 years ago? I only know of a few names, but you guys know which ones I'm talking about, Gotham Deezil, etc. Is that really any different today?

Greg

Yes I agree that in "those" days there were rubbish diesels too. Over here we used mostly diesel engines in our CL planes espescially Webra and Taifun
and we always did handstart them. (who had heard of electric starters then anyway? besides these are a nono in any case) I know nothing of CNC, can a correct taper be machined on CNC ? What I do know is that lapping is not for everyone's skills and understanding. I have learned it from old friend Harry. It is all a matter of FEEL. When you turn around a Benno Schlosser you feel (or do not feel ...) the delicate springy-like compression : that's high class workmanship. When I first started my Mk-1 and 2 tiny fragile Frogs I had some doubts but they sprang alive quickly. One funny thing : I have had a few CNC lathe operators visiting and when they stand in front of my Myford they raise hands not knowing what to do ! It is a different handling of machinery I suppose ?

The late generations of CNC-machines work with tolerances that small that it's really beyond our understanding...

I figure (without actually knowing...), that it would be possible to program a modern CNC-machine to make accurate liner/piston fits for diesels......IF...the operator knows the parameters required, that is....

And that's where I see the real problem...!
Just how do we "translate" a master lapper's "feel" into computing digits...?...maybe an impossible task, particularily if the importance of this isn't fully understood all the way out...!
As long as this "communication" bit isn't sorted, we're probably dependant on Human Skill....
Which gives a heartwarming feel somehow, if you ask me...in these days of hi-tech-hype, the human hand deserves to win sometimes...

Bob, a few comments:
1. Quality control problems aren't new, they've always been with us.
2. Monty Tyrell unfortunately picked about the worst example, some Frog 250s were very nice engines... and some weren't...
3. M.T. wouldn't have made those comments if Hearns had been importing ED instead of Frog.
4. The list of "good" diesel makes I gave certainly isn't complete, but it isn't "random" either. There are deliberate omissions.
5. All this discussion was sparked off by Fiery's comment about modern "quality" CNC diesels that are so good that it's impossible to hand start them, for the reasons I mentioned.
6. I'm sure you'll understand that I get cross when such engines are called Elfin, ED, Amco, Rivers or Oliver, and that many of our "new world" friends think that diesels are that ****!.
7. I'm pleased to see that CS have stopped using the word "Oliver", now only "Tiger" (probably fearing legal action by Tom Ridley...). We're supposed to forget that they were riding on the Oliver name for years, until the quality difference got just too ridiculous.
8. Reggie's comment about Webra and Taifun is valid of course, but it's also the direct result of 60's and 70's EEC trade regulations.
9. I like GH's summary. I'm sure he's right, but it doesn't solve the problem of the thousands of b-awful "Elfins" and "Mills" like Fiery's engine that are out there, driving any normal modeller to glow or electric...
10. I can't be the only person who's noticed that, in terms of practical operation, the modest "Indian Mills" is far superior to the Russian/Chinese "Elfin/Mills", etc.

Originally Posted by Gluehand

The late generations of CNC-machines work with tolerances that small that it's really beyond our understanding...

I figure (without actually knowing...), that it would be possible to program a modern CNC-machine to make accurate liner/piston fits for diesels......IF...the operator knows the parameters required, that is....

And that's where I see the real problem...!
Just how do we "translate" a master lapper's "feel" into computing digits...?...maybe an impossible task, particularily if the importance of this isn't fully understood all the way out...!
As long as this "communication" bit isn't sorted, we're probably dependant on Human Skill....
Which gives a heartwarming feel somehow, if you ask me...in these days of hi-tech-hype, the human hand deserves to win sometimes...

That is what I ment, can that feel be translated to CNC ? Do'nt know. And are there full size engine applications needing taper between piston and cylinder at the top ?

For those that haven't already read it, here is the story straight from the horse's mouth. And for European viewers - you will find a few strange words in here. Ivor was keen to promote a new form of English, in which the word is spelt the same way it is pronounced, thus "said" becomes "sed"

I have run and flown a number of diesels of all stripes. I have had a few which I could not even get to fire. They looked good and felt good and nothing wrong that I could find. One was a Super Tigre G32, the red head, rear drum intake 1cc. I sold it on eBay to a guy in England. About six months later he sold it on eBay. We both got our money back. I've also had the G31, the similar 1.5 cc engine. It started and ran very well.

Hi Jim,

First, humbly, I think you mean G32. This was red headed, 1 cc, and with rear drum induction...
If your engine just "popped on the prime", my first - and last - thought is that there might have been some kind of gasket issue... As the ST's were so well built, I can not imagine anything more serious than that... My "middle thought" goes to the rear drive disc....if it has more than one hole to catch the crankpin, it might have been fitted in the wrong position....mind, the disc of my ST G15RV has indeed 2 optional holes...


"Popped on the prime", was just what a Czech "Start Junior" 2 cc did to me....
Occasionally it would do a short run, but mostly it just "popped".....
When cleaning it, at a later stage, I noticed a grayish spot of oxide at the crankcase inside. When trying to rub the oxide off with a wooden dowel, it just went through the crankcase wall (see pic). As you can see, part of the crankcase wall is extremely thin, some of it consisting of just oxide & gunk....and it was virtually invisable from the outside...! Obviously air must have leaked through the small pores.....
Now I think this is weld- or solderable - but I did learn something on hidden faults, and on castings in the process...

Thanks, I corrected the number. That Junior looks very different from mine, an MVVS, which has the intake on the same side as the cylinder. The Aeromodeller review of the G32 was fairly critical. Maybe that affected me. I traded for a second hand Rivers Silver Arrow. I fooled with it for a year or so and never got it to run. Then I found an Aeromodeller review about what a wonderful engine it was. I went and put it on the test stand. It started right up and ran fine, and continued to do so.

Jim, I'm surprised, I've owned several ST G32 engines and they've all been great runners, and the same goes for the Rivers of course.
I particularly like the G32, it's just a little bit more sophisticated than most 1cc diesels, and with ST performance.
When you mention Aeromodeller reviews... Hmmm. Ron Warring was a great aeromodeller but, concerning engines, he wasn't up to Peter Chinn's standard (and neither was anyone else!).

Originally Posted by Jim Thomerson

That Junior looks very different from mine, an MVVS, which has the intake on the same side as the cylinder.

Yes, this "Junior" is a non-MVVS....it was made by a Czech manufacturer called "Start"...it is mentioned in one of Jiri Kalina's books (unfortunately I don't understand much of the text though...)

I also received these words from a Czech forum reader some years ago:
" Junior 2 were one of most used engines in 60s. This engine was used in all categories. Junior 2 was produced in 1958 in the company "START" in Prague.
Bore: 13mm
Stroke: 15mm
Displacement: 2cc
"