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Dave

2024-06-11, 20:02:05
Have you tried the new Drafts feature yet? I just lost a long message today and learned my lesson. It is a good idea to save a draft of any long post you are writing. You can then just keep writing and keep saving a draft, knowing you have a backup if there is a glitch. The draft is automatically deleted when you post the message.

Dave

2024-06-08, 18:30:04
For Sale
xman has two very nice 1950's machines available - a green 1950 mk4 and black 1951 mk5 - both in good condition and running well.

Dave

2024-06-07, 02:13:36

Dave

2024-06-03, 08:23:05
For Sale
Duncan has just listed his green and cream 1957 Dragonfly for sale with spares and documents.

Dave

2024-06-02, 08:34:05
Parts avalable
alistair still has parts available - barrels, carburettor, castings - see all listings.


Dave

2024-06-01, 18:33:27

Dave

2024-05-28, 00:09:46
Welcome to the new site!
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Learn all about attaching photos in the User Guide. Any problems with anything please Contact us     Faulty links fixed - 01June2024

Question about setting the ignition on my T6.

Started by ManfrerdSt, 07 Nov 2016 at 17:06

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ManfrerdSt

How can I adjust the ignition timing of my T6 with BTH magnets exactly?
The drive of the magnet and the contactbreaker sit with a key on the armarture. The magnet can not be twisted.
Am grateful to every tip
Regards
     Manfred

eddie

Manfred,
             If you turn the engine to the correct firing position, then remove the generator and it's drive sleeve, you should be able to see the small idler gear that drives the generator. Insert a piece of wooden dowel into the gear to extract it - you will now be able to turn the magneto until the points are just about to open - then replace the gear, the sleeve and the generator.

Regards,
              Eddie.

ManfrerdSt

Thanks for the quick reply Eddie!
I will try it. However, it is a tooth to tooth adjustment. There is probably no stepless adjustment.
For another question see Attach-picture
Regards
     Manfred

eddie

Yes, Manfred, you will only be able to adjust the timing by one tooth increments, but the S6/T6 motors are only in a soft state of tune, so it is not imperative that the timing is spot on. Always opt for over advanced rather than retarded, as you can then play with the advance/retard lever to find the 'sweet spot'. Also, bear in mind that we now use fuel that is nothing like that available in 1930, so the engine is likely to run sweetest with a different amount of ignition advance to that specified in the handbook.
  As far as I am aware, there is no spring inside the generator coupling sleeve.

  Regards,
                 Eddie.

ManfrerdSt

OK, THANKS!
another question!
Was this version optionally on the T / S6 or E31 or is the own construction?
Regards
     Manfred




eddie

I think this dynamo option was only fitted to the 1933 models.

  Eddie.

Dewey

Eddie,
What is the purpose of the nipple in the rear intake tract? it was blocked off on the engine I worked with but I couldn't imagine why it was there in the first place. Starting aid?

Dewey

rossco

#7
Hi all that timing cover with the ribbed inlet manifold was from one year only, 1933  this could be a D33 or an E33 600cc side valve depending on the tune of the engine and a few other small items. Not too many left in the world. All the Best Rossco.

ManfrerdSt

Hi all,
I have the lid removed and looked at
The housing under the cooling ribs is double-walled. Between the intake duct and the cooling fins is motor oil. This means that the cooling fins function as an oil cooler. The nipple is the connector for the oil pressure gauge.
A spare part list specially for this engine would interest me very much.
Regards
     Manfred


ManfrerdSt

Does anyone know which carburetor is needed here  :question: :question:
It would have to be a standing carburettor.

Regards
     Manfred


David Lawrence

Hi Manfred,
With regard to the S6 manual and illustrated spares list, the Douglas Club does keep a stock of reproduction copies of both which are available to Club Members and non members, however we do charge a small extra for non members simply because the prices are calculated to be a service to Members making  only a small profit to enable us to expand the range of publications available.
If you care to email me direct I will give you more information.
Dave

Dave

Rossco kindly sent in this information and photos.

Quote from: RosscoOn my E33 it is an Amal ( like the sketch attached) but is downdraft and not updraft as in the 600cc – 700cc for 1929-1932. The change by Douglas was easily done , undo two ¼ inch screws and turn the bowl 180 degrees. I have attached some photos and info on my bike that may help.





Higher quality view

Doug

A closer view of the carburetor in down-draught position.



-Doug

ManfrerdSt

Hello Rossco, Dave and Doug,
Best thanks for the info!
Doug,
there was the bike 1933 750 or is that a conversion

Regards
      Manfred

Doug

Manfred,

The 750cc variant was first cataloged in 1934. It is clearly based on the T6/S5/S6, but the sump was eliminated and a change was made from the BTH magneto to a Lucas Magdyno. The engine therefore sat lower, and mounted directly to the frame tubes. At the bottom of the timing chest, a gear oil pump was used (rather than the vane type of the S6) that supplied oil and scavenged it back to the compartment in the petrol tank. The 1934-35 750cc barrels will probably fit on the earlier crankcases.

There is a 1934 Z1 (750cc) in the photoguide section here:
https://www.douglasmotorcycles.net/index.php?topic=1991.0

-Doug

eddie

Manfred,
              There were some 750 machines produced alongside the S6/T6 - the H32 Mastiff, but there were problems with the valves being very close to the bores. On later models (Z and Z1), the valves were moved further from the bores.
  Regards,
                Eddie.

Doug

Oops!  I forgot about the 1932 Mastiff!   :oops:

-Doug

ManfrerdSt


I think in 1933 there was only a 600 (or smaller).
And only in 1933 there was the engine with finned intake duct, which also functions as an oil cooler.
A motor as in the photo of Doug is a mixture.

Regards
     Manfred


Dewey

Doug,

I couldn't help but notice that the pic you have shown also appears to have a nipple in the rear intake tract. Why is it there?

Dewey

Doug

Dewey,

I don't know, I have never had the opportunity to examine a D33 inlet manifold inside and out. As Manfred reported earlier in this thread there seems to be a double wall and cavity around the inlet tract. The conjecture that it was probably for oil cooling is very likely, but Douglas decided not to carry through with it in practice. Possibly they realized they would shed heat from the oil via the oil compartment being located in the petrol tank and the complications of routing the oil through the manifold was unnecessary. In 1934-35 advertising they did make mention of that feature. They even passed several tubes through the oil compartment to allow the petrol to traverse the compartment and so increase the heat exchange surface area.

The alternative was that it was to prevent carburetor and manifold icing, but they probably picked up enough heat by the manifold being integral with the timing cover. Also the presence of fins does rather suggest the goal was to get rid of heat, not conserve it.

-Doug

ManfrerdSt

#20
Here a few pictures of the oil cooler solution

Fig. 1 shows the flow to the oil cooler

Fig. 2 shows Return line

Fig. 3 shows the double wall of the intake manifold

Regards
     Manfred

eddie

Ah! - now I think I understand how the 1933 oiling system works. On the original T6, the oil was delivered from the pump through a vertical gallery to supply the crankshaft, and camshafts (via the tubes on the outrigger plate), with the excess pressure lifting the oil indicator (on top of the timing chest), thus allowing the excess to spill back into the timing chest and back to the sump. On the 1933 models, the top of the gallery is presumably blocked off and the excess flows out through the camshaft feed banjo bolt into the inlet manifold jacket, to return to the timing chest via the relief valve - hence the oil pressure gauge take off being on the manifold ('33 models had a dial type pressure gauge in the tank panel). This system would then provide some heating for the manifold (to prevent carb icing), and a degree of oil cooling when the engine is up to running temperature (with extra assistance from the fins) - the original S/T6's have been known to run exceedingly hot!

  Eddie.

ManfrerdSt

Hello Eddie,
it is exactly like that!
The oil indicator (on top of the timing chest) is not available in the 33s.
I hope I have brought some light into the darkness
Regards
     Manfred


eddie

Hi Manfred,
                 You sure have shed some light!! I also notice that you have the dreaded cracks in your timing cover - this is usually caused by the wrong tightening sequence of the 4 crankcase studs. With the timing cover off, and the outrigger plate loose, the 4 studs should be tightened from the left hand side, so that they clamp up the 2 crankcase halves and the primary chaincase. The nuts should then be tightened to secure the outrigger plate. The timing cover can then be replaced - having checked that the surfaces mate correctly - and only use a thin gasket (too thick a gasket will cause the cover to distort again). Incorrect tightening sequence can result in everything appearing to be tight but with the internals loose and the timing cover taking any loads generated within the engine.

  Regards,
                Eddie.

ManfrerdSt

Yes, I saw the crack. But this is no longer an issue with today's Leas welding technology.
Regards
     Manfred


Doug

Manfred,

Thank you for the details. I had imagined it used external oil lines, and that Douglas had not followed through with the implementation. The reality is a lot more elaborate than I thought!

-Doug

Dewey

Manfred -
I too would like to thank you for both the visual and written explanation. I thought it odd that the intake tubes on the H32 I worked on appeared so thick. It never occurred to me to be double walled, but the concept has merit. Warm the intake charge and cool the engine oil all at the same time. Of the 2, I imagine cooling the oil would be most important.

Dewey