By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by CML

DC Darts Puzzle

All Topics | Latest Posts

Search for:  in Thread Title in  
onetenor20/09/2017 23:11:03
1371 forum posts

I recently acquired a couple of DC Darts. One a redhead and the other an ali head. I noticed that the Carb inlet sizes were different. I can't compare it with my 3rd one at present but me Bantam which shares the crankcase is a bigger than both. I'm puzzled Should I drill/ ream out the smaller one or leave alone? Also anyone know thread size of the comp screw ?

J D 820/09/2017 23:35:40
avatar
689 forum posts
50 photos

The DC Dart was produced over a number of years and was previously called the Albion Dart. There are likely to have been several changes to the Dart over its nigh on forty year production.

I would leave alone.

Robin Colbourne20/09/2017 23:40:58
avatar
342 forum posts
4 photos

The DC Bantam, a glow engine, runs on methanol which has a pretty low calorific value in comparison to diesel/kerosene/paraffin, so more methanol is required and more air too. Even so they were pretty gutless.

The larger the venturi size on a diesel, the harder they can be to start. Either the Dart venturi was reduced for easier starting, or enlarged for more power.

Thread sizes on DC engines tend to be odd numbered BA (British Association) sizes, so its probably 5BA,

Regarding modifying the venturi; if it ain't broke, don't fix it!

Edited By Robin Colbourne on 20/09/2017 23:41:20

brokenenglish21/09/2017 07:20:06
avatar
254 forum posts
21 photos

The problem is that at least one of your Darts has been messed with.

I don't think any DC Dart ever had a plain alloy head. The heads were mostly red of course, but some of the later ones were gold.

So if you remove the plain alloy head and look "inside", you may well find the original colour.

The very first Allbon Darts (not Albion! who wrote that!) had a light green head, and many of these have faded a lot, to become almost plain alloy today, but these engines were/are Allbon (early fifties), not DC.

The engine with the smaller carb. bore will be a fairly late model. In the eighties, when they were produced a little bit "quick and nasty", the venturi intake was left as a sort of "oblique flat surface", like yours. That "generation" is frequently "not very good", and quite a few were sold as non-runners (young manufacturers who took over and didn't really know what they were doing...).

One point eludes me. If the engine was manufactured with its present venturi (which it was), why would you want to ream it out? Are you dreaming of a "tuned" DC Dart?!! Increasing the venturi cross-section on a small sport diesel isn't likely to have any effect other than making it more difficult to start...

J D 821/09/2017 09:23:41
avatar
689 forum posts
50 photos

I did think the name was Allbon or Albon,however many modern sites do say Albion and I copyd that. My mistake.

brokenenglish21/09/2017 20:15:31
avatar
254 forum posts
21 photos
Posted by J D 8 on 21/09/2017 09:23:41:

I did think the name was Allbon or Albon,however many modern sites do say Albion and I copyd that. My mistake.

Sorry JD ! No offence !

onetenor21/09/2017 21:01:52
1371 forum posts

The name IS ALLBON as on my Javelin. The Darts' daddy.I'm not looking for a "tuned " DART BUT just wondered if there would be any advantage in opening the venturi. .Re the Bantam the one I have it must have been a really good day When that was made. It is a real cracker . Easy to start and very good power .A 5x3 3 bladed KK prop is it;s weapon of choice. Used mostly on air driven boats has given excellent service and still going strong.. Must have been my lucky day. Thanks for all replies peeps. Regards John

brokenenglish21/09/2017 21:24:43
avatar
254 forum posts
21 photos

I wouldn't touch the venturi.

Firstly, does the engine run OK?
If it runs OK, leave it as is!!!
If it doesn't run, then opening the venturi certainly won't fix it!!!

onetenor21/09/2017 22:53:07
1371 forum posts

Yep both run and start easily. Not put my tacho to them yet..It's only a reed / wire type but could supply a comparison .reading just out of interest .It will have to wait until I am on my feet again. Regards John

onetenor25/09/2017 13:52:53
1371 forum posts

Hi again. The Dart with the plain ali head appears to be one of the pink early models and the reamed venturi.There is a faint trace of pink still inside. There also seems to be number 11 stamped either side of head not quite diametrically opposed so don't think they are tool marks.. Odd engine altogether. Pink ones were Mr Davies favourite coloured ones. Anyone know where I can find one of the original dismantling tools?

onetenor25/09/2017 14:03:13
1371 forum posts

Here is a pink one on test https://www.youtube.com/watch?v=KshMX4ZMMUE

brokenenglish25/09/2017 15:03:08
avatar
254 forum posts
21 photos

John, there is no "pink" one. It's just a red head faded!

It's amazing that the engine ran at all with a yard and a half of fuel tube and the tank well below the engine!

onetenor25/09/2017 16:55:41
1371 forum posts
Posted by brokenenglish on 21/09/2017 07:20:06:

The problem is that at least one of your Darts has been messed with.

I don't think any DC Dart ever had a plain alloy head. The heads were mostly red of course, but some of the later ones were gold.

So if you remove the plain alloy head and look "inside", you may well find the original colour.

The very first Allbon Darts (not Albion! who wrote that!) had a light green head, and many of these have faded a lot, to become almost plain alloy today, but these engines were/are Allbon (early fifties), not DC.

The engine with the smaller carb. bore will be a fairly late model. In the eighties, when they were produced a little bit "quick and nasty", the venturi intake was left as a sort of "oblique flat surface", like yours. That "generation" is frequently "not very good", and quite a few were sold as non-runners (young manufacturers who took over and didn't really know what they were doing...).

One point eludes me. If the engine was manufactured with its present venturi (which it was), why would you want to ream it out? Are you dreaming of a "tuned" DC Dart?!! Increasing the venturi cross-section on a small sport diesel isn't likely to have any effect other than making it more difficult to start...

Despite this reports are that the earlier reamed spout models were more powerful than the later unreamed models.I think some time in the future I will try and compare the plain to the reamed. i.e. test it plain then ream it. I can easily replace it with Lumiweld or similar if no improvement . Or if starting gets harder

J D 825/09/2017 18:23:58
avatar
689 forum posts
50 photos
Posted by brokenenglish on 21/09/2017 20:15:31:
Posted by J D 8 on 21/09/2017 09:23:41:

I did think the name was Allbon or Albon,however many modern sites do say Albion and I copyd that. My mistake.

Sorry JD ! No offence !

None taken brokenenglish, Davies of DC came from a small hamlet not far from me,although known as Evan Davies this was an anglicised version of his old welsh name "Hefin". Cheers John Davies. [No relation as far as I know.]

John Emms 125/09/2017 19:42:04
223 forum posts

Albion made BIG diesels lol.

I had a Dart as a young teenager, and that was really quite powerful, at least as powerful as my .049 glow engines. In addition, if you want to use big props running slowly, you will want positive airflow through the venturi, and the current size of venturi will give you that. Enjoy!

Bert25/09/2017 20:11:14
494 forum posts
7 photos

DC Darts were produced with plain ally heads at some time or other, I have one new in the box in my engine drawers . If I get the time I'll fish it out and see what year it was made.

brokenenglish25/09/2017 20:22:20
avatar
254 forum posts
21 photos
Posted by Bert on 25/09/2017 20:11:14:

DC Darts were produced with plain ally heads at some time or other, I have one new in the box in my engine drawers . If I get the time I'll fish it out and see what year it was made.

Interesting... Bert please fish it out. "Never say never" and all that, but in 55 years of engine collecting I've never seen or heard of one. Perhaps, right at the end, when they were in all sorts of problems and production was a little "disorganised"... Please try to post a photo.

Engine Doctor26/09/2017 10:15:04
avatar
1817 forum posts
4 photos

There is a good history of the Dart on www.modelenginenews.org . I have had many of them over the years while collecting but never seen a plain alloy head on one but doing a Google search there is a pic of plain alloy dart ! As already said the last ones made were of varied quality and material choice was often poor. I steer clear of the late DC engines as Conrods and cylinder/piston assemblies were at best poor and if you got a good one you were lucky. The thick walled Venturi intake was due to poor casting on later models. The late model DC engines were easy to spot , apart from the Venturi  they had fewer fins obviously to reduce machining times and cost and a horrible plastic tank with pressed alloy inlet/ outlet . Re the pink headed Dart . I do remember as a youngster seeing a new one in our local model shop window that had a pink head . In the above article you will see that two batches of Darts had pink heads.The article also has explanation why the external appearance( quality) changed due to different tooling etc .

Edited By Engine Doctor on 26/09/2017 10:24:58

Bert29/09/2017 07:42:48
494 forum posts
7 photos

This is the unanodised Dart that I have, it's never been mounted and is as new, the phoss aren't very good. Unfortunately the guarantee hasn't been filled in so there is no date but the spares list shows it to be post decimal currency so I imagine that would be in the most chaotic period of production,

img_0639.jpg

 

img_0638.jpg

Edited By Bert on 29/09/2017 07:44:33

brokenenglish29/09/2017 07:59:11
avatar
254 forum posts
21 photos

Bert, Thanks! I think your assumption is probably correct. There must have been a period, towards the end, when "any ol' thing" left the factory.

In any case, the fin profile and alloy tank show it as a late model. The profile isn't a curve, it's largely "straight" and parallel, which is a late model.

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of RCM&E? Use our magazine locator link to find your nearest stockist!

Find RCM&E! 

Email News - Join our newsletter

Love Model Aircraft? Sign up to our emails for the latest news and special offers!

Latest Forum Posts
Support Our Partners
CML
electricwingman 2017
Gliders Distribution
Expo Tools 14 July
Wings & Wheels 2018
Airtek Hobbies
Overlander
Slec
Sarik
Advertise With Us
Latest "For Sale" Ads
How has your building graduated?
Q: Did you start with ARTF and move to building from kits or vice versa?

 Started with ARTF moved to building from kits only
 Started with ARTF moved to building from plans only
 Started with ARTF moved to building from kits and building from plans
 Started with building kits or from plans and moved to ARTF
 I only build from kits or plans
 I only build ARTF
 I only build from kits
 I only build from plans
 Other (Please specify in thread)

Latest Reviews
Digital Back Issues

RCM&E Digital Back Issues

Contact us

Contact us