greggles47

I have (for my sins) acquired a newish DC Dart. So far it has resisted any attempts to start. It'll kick and run off a prime, but sustained running is so far not happening.

I am using old but reliable fuel. 25% Castor, 30% ether & 45% kero. Does it need to go to the old reliable 1/1/1 mix?

It has what I believe to be a genuine NVA, but it seems to be feeding too much fuel, it's a two hole spray bar and I think a BA (very coarse) thread. Is this an issue with them?

Most attempts have been wit ha 6X3 prop. but a 7" has had similar unspectacular results.

Any thoughts and tips will be welcomed.

Thanks

Greg

qazimoto

My Feedback: (1)

Greg,

my two runners (one Albon, one older DC) go very nicely on either a Master 6 x 4 or a Master 7 x 4.

The dud (a late model DC) won't even fire and I strongly suspect a sufficient lack of Mr. Cylinder Compression is the culprit.

I was told to check the cylinder to crankcase gasket thickness as a nonstandard one would alter the exhaust timing dramatically.

It was the same as the others.

If yours will fire then half the battle is won.

I suspect that the NVA thread may be 2 BA which was fairly common with DC engines.

I have only run mine on oily ex-TR fuel.

How's the compression? The late versions were supposed to be the worst.

Ray

fiery

My Feedback: (2)

Greg

If it is running off a prime that has to be good.

It sounds like fuel metering may be the issue.Can you upload a photo of it?

As I recall mine has the original NVA and it does not want it's needle wound out very far.


http://www.rcuniverse.com/forum/m_11097017/tm.htm

ffkiwi

Two points-first the spraybar and needle thread is 5BA (2BA is huge!)-and secondly-not all DC needles are equal-though at first glance they may appear so! [I'm talking about the post 1950s NVAs with the plain aluminium thimble] -the actual length of needle projecting beyond the thimble varies-and if there has been a mismatch or a replacement needle fitted this could cause the problem. Have you another DC needle you can fit? I'd also check your backplate tightness-as a primary compression leak won't do anything to improve the fuel draw. Many of mine (and I have quite a few) will run with the needle only 1-1/4 to 1-1/2 turns open-so if you've gone for the standard 3-4 turns open flooding is just about guaranteed! Starting will be a lot easier on a 7" prop-try a Master 7x3 if you can lay your hands on one-it's the perfect prop for 0.5 diesels-not too much blade area, plenty of diameter and reasonably thin.
If your Dart has a yellow (or gold if you're feeling poetic!) head-then take care, as this is the from last batch that all had brittle shafts. Also check the venturi-if it has a taper to it-(put in with a tapered reamer) then this is a 60s or 70's Dart-the later ones were left 'as cast' -and were not as good engines as the earlier ones.
Your old fuel might have been 30% ether when it was mixed-but what is it now? 1:1:1 not a bad idea on a new motor.............

ChrisM
'ffkiwi'

Finally-Darts have always been variable-there are good ones-......and there are dogs............

greggles47

As requested, here's the little beastie.

After about an hour of unresponsive flicking, I stripped it down.

Notable finds - Backplate - nearly finger tight. Fibre washer between cylinder & case, about 1mm thick. Case containing large lumps of died fuel/castor. All fits seem to be satisfactory, all ports open.

NVA checked to ensure closing off - check!

Reassembled ensuring backplate tight. Cylinder ditto.

What thickness should the cyl gasket be?

qazimoto

My Feedback: (1)

Ah yes those pesky BA threads!

The smaller the number the larger they get.

That NVA certainly looks like standard DC.

I'll check the thickness of the cylinder washer tomorrow, but I reckon that tightening the backplate may have fixed the problem!

Are those hold down screws real genuine Cheesehead, Brass 6 BA circa 1963?

Ray

greggles47

hahahaha! MAte nothing gets by you. Those cheese heads have been rattling around my box of odds & sods for eons! I probably even bought them from Robbyco!

No the tighter backplate was not a winner.

I'm out & about tomorrow so looks like Wednesday before I can look again, but I think I'll make a little batch of 1:1:1.

OR

Just give up & give the motor back to the owner and tell him he's just become " A COLLECTOR "

gossie

I ran my DC Dart only a couple of days ago for fun and to make a bit of nice noise.......Well nice to me.

I've always used the 1-1-1 fuel with a dash of DII, and a 7 X 3 old nylon prop. That's the only prop. it had ever run on in all the years I've had it in a couple of FF models, so after the first tankfull I changed over the prop. to one of Peter Burfords white plastic ones that Gordon gave me to try out on Cox TD .049s.......Maybe 6 X 3????? She screams her head off and sounds very sweet.
It has the horrid spring start on it and using that it's almost an instant starter. Flicking usually takes 4 or 5 flicks. It does like an exhaust prime as well as a couple of choked turns.

Mix a small brew of 1-1-1 Greg. and see how you go. Will be interested to hear.

paw080

Hi Greg, It's hard to make a decent diagnosis, without physically inspecting your engine.

I do recommend that you do not use the ancient 33% fuel formula. I think you should

bump the ether to 35%, drop the kerosene to 40%, drop the castor content to 23.5% and then

add 1.5% of Ignition improver such as DII or Amyl Nitrate. a 6" X 3" prop is just fine for

running. Start by making sure the Dart is not flooded; then open the needle about 1.5 turns

and choke so that the fuel is pulled up to spraybar ONLY - NO further. prime very lightly and

start flicking the prop. If it doesn't fire, lightly increase the compression until it does fire.

Both my darts run very well with Cox 6" X 3" props and the fuel I use is 20% Castor-35% Ether,

43.5% Kerosene and 1.5% DII. They power 130-150sq" control line sport models on 35' x .012" lines.

Best of Luck;

Tony

Recycled Flyer

Chris M did say in Derek's provided link that the gasket was also 1mm in thickness so it sounds like the normal standard.

".........for a start, DC Darts all have a fibre washer under the exhaust flange to seal the join-(look at the photos I posted earlier-and compare the DC Darts with the Allbon Darts) a paper gasket would do the job just as effectively-but be a little fragile-the fibre washer raises the liner by a significant amount-at least 1/32-1mm-which would be sufficient to change the exhaust and transfer timing."

ffkiwi

Jon Fletcher and I discovered this several years ago-in what might be termed a 'model engine archaeology' session -that there was considerably more variation (or perhaps sub marks) in the Allbon Darts than had been generally realised-and it was largely centred around the cylinder machining. Early Darts showed quite a lot of variation-but generally had only a thin paper gasket-or no gasket-under the exhaust flange. Somewhere along the line-probably the late 50s or early 60's, DC started putting the fibre gasket under the liner. This would definitely change the exhaust and transfer timing...........provided the cylinder liner itself was not changed-but this is by no means certain. Anecdotal evidence from several sources suggests that the earlier Allbon Darts were more powerful than the DC ones.

ChrisM
'ffkiwi'

AMB

Interesting history. minor changes have a dramatic effect all it takes is a gasket difference to produce them martin
but you are dealing with a tiny engine

fiery

My Feedback: (2)

They are a lovely little engine. I really like mine and I like the "quickstart" spring starting device too.

I would love a set of instructions for the Dart, is anyone able to upload them?

ffkiwi

A bit more detail:

The Dart first appeared late in 1950 (literally just in time for Xmas!)-this was the Allbon Dart Mk1-with a green anodised head, no integral tank, and a plain un-knurled prop driver. More importantly-it had a captive gudgeon pin set up (ie the pin was retained internally) and three internal transfer grooves at 120 degree separation. The piston had a truncated conical top. A second version of the Mk1 had the more conventional 'through bored' gudgeon pin setup (I have one of these)
A couple of years later-ie ca 1952/53 the more familiar Mk2 Allbon Dart appeared-with a redhead, and revised cylinder porting-now there were three external semi-circular transfer passages cut on the outside of the liner-terminating in angled oval transfer (ie circular-but drilled on an angle of about 30 degrees, resulting in an oval opening) ports-but still with a conical piston. An integral rear tank was now fitted.

About this time (1953-ish) Davies Charlton took over production of the Dart and the 1.5cc Javelin-the two designs were virtually identical apart from size. The Javelin gave rise to the Mk1 Spitfire, and then both were dropped in favour of the cheaper Sabre design, meantime the Dart continued on unchanged externally until sometime in the late 50's when 'DC Ltd' replaced 'Allbon' on the crankcase casting. Somewhere along the line-and its hard to say when exactly, a flat topped piston replaced the earlier conical one. This was probably accompanied by some timing changes-and may well have been done at the same time as the thick cylinder gasket started to be used.

The spring starter didn't appear until the very early 1960s-and was probably instigated by the introduction of the Bantam 0.75cc glow-launched in late '59 (once again -just in time for Xmas-DC weren't stupid!) which used the Dart crankcase (machined slightly differently). From the early 60s onwards until the late 70s there was virtually no change until the last series-which had the un reamed venturi, and a head with parallel fins.

I'll try and post some pics later...........

ChrisM
'ffkiwi'

AMB

Chris think we all thank you for such a detailed history of these great little gems sadly I have no examples of any, lucky you are martin

ffkiwi

Martin-there are still gaps in the story-but 60 years on, it is going to be hard to fill them. Not helped by DC not stamping their engines with a serial number-though they do number them in the box, the exception being the Wildcat and DC 350 which do have serial numbers. With the Dart in particular having a production life of over 30 years-we can only accurately distinguish the very first ones and the very last ones. The 50's show numerous small changes, whereas from ca 1960 through to 1980 there is little if any obvious change in the engine's appearance. At least ED's you can accurately date, from the serial numbers and knowing when various models or variations appeared. Its even more mystifying when you know that DC were manufacturing the Frog engines (in direct competition with their own designs) from the mid 1960s onwards-and they put serial numbers on those!

ChrisM
'ffkiwi'


....and none of this is helping greggles much..............

AMB

A bit off topic ( way off ) found this packed away for decades, I know steam is dead too) sight glass on boiler cracked, a call to toys of yesteryear had one in a week
these any many more still made in the UK and Germany, not cheap you can get the African Queen for about $700 steam powered of course, Neat can run mine on the kitchen counter
drink my coffee, and smell the hot oil in the steam

greggles47

Chris,

Thanks for the background, I'm enough of an anorak to actually like that stuff.

"My" Dart, is DC Ltd , flat top piston, no sign of a spring starter, and although there is no tank, the back plate is set up to carry one.

I've been a bit preoccupied with Mrs G's health issues for the last couple of days but hopefully tomorrow will be able to mix a new batch of fuel, 25 C- 35 E- 40 K and I've been advised to lower the tank to prevent flooding. OF course a 7" prop for good measure.

Will advise of my outstanding success in due course. I'm not going to let this little beauty get the better of me. It's just way too pretty to be a glass case special.

G

qazimoto

My Feedback: (1)

Martin,

live steam models are far from dead. A good modelling friend has taken them up seriously now his knees have left him struggling to do active flying.

Just about everything is available here and in the UK, and I'd be very suprised if that wasn't the case in the USA as well.

See: http://www.ejwinter.com.au/ for a comprehensive catalog.

Also Google "Garden Railways" for smaller gauge trains which combine live steam with electric devices, serious electronics, R/C etc. and are much more affordable than the bigger gauges.

I've seen one loco on the web which uses a Mills 75 diesel for it's motive power.

Ray

qazimoto

My Feedback: (1)

Greg,

you're welcome to my dud as a source of spares if you need 'em.

A suitably useful tank can easily be turned up out of aluminium as well.

Sorry to hear about Mrs. G, Laurel has been unwell lately as well.

Ray

greggles47

Ray,

I was thinking of a delrin tank for it - but I'll only waste time on the lathe once I get the little blighter running.

Hope to get a shot at it tomorrow. I know we'll be home most of the day, we're have some concreting done.

Give our regards to Mrs Q

G

AMB

Greg hope your wife doing better, and guys of course the steam thing being dead was a joke, a parody of the post months back ^ diesel is dead "I was not aware of the steam supplier down under, do not think this niche invaded by China yet, OS I think still makes steam model locomotives martin

I SEE BOLTON DOWN THERE HAS BEEN AROUND SINCE 1922
ON THE STEAM THING OUR CLASSIC DIESELS GONG BACK TO THE 50S ARE YOUNGSTERS




"

Steve_P.

My Feedback: (38)

The D-Cstarting instructions are attached.

gossie

I just got my DC Dart out for the second time in a week, not to run it but to see what I could see on and in it.

I purchased it from the late Paul Straney in about 1980 without a box but it looked very new.  Paul said he had never run it but bought it some years before without the box etc.

It has the spring start and a clear plastic tank and a conical piston......Does not look flat at all.   So what year might it be?

As mentioned earlier it starts and runs without a problem.

FWIW back in the '50s ('53 or '54???)I bought a brand new Allbon red head Dart from Hearns Hobbies in Melbourne that I had in a couple of FF models including a CELERITAS as my DC Dart is in now.   Great small flier for a Dart.
About '55 I was given, yes given an Allbon Dart from a guy who just never wanted it. 
 Rather than the very red head as on my Allbon version, it was a pinkish shade.  Guess things got changed all the time.

Unfortunately I flogged them plus many other engines in 1958 when I went MG TC happy.  

qazimoto

My Feedback: (1)

No they're not!