My new E28

[Ian]

Hi folks, I have just taken delivery of an E28 600cc outfit and have to do some sorting before the Douglas Rally (hoping to take it). I don't have any books yet on it but have a few questions :

1. Carburetor - it has a very small B&B on it at the moment - looks far too small to me - what size carby would suit one of these ? I have access to an Amac TT which looks about the right spiggot size.
2. Oiling system - it has two pipes - one to the mechanical pump/oil glass which has a tap to shut it off when not in use. The other is direct from the hand pump - however this has no tap. I presume the hand pump on these is supposed to seal completely when depressed - or do most people put a tap on it to stop filling the sump when left standing ?
3. What are the ignition and valve timing settings for these ?

Thanks in advance for any help !

[Ian]

I just pulled the B&B - its a throat of about 11/16" - looking at the manifold I would expect the carby should be 7/8" ?

[Doug]

Ian,

The 600 used the same B&B carburetor body, the 123-5, as the 350 models except for the choke size. My 1928 is bored about 3/4", so yours sounds about right. Per the handbook the standard jet was 90, once run in you could lean it out for maximum fuel economy with an 85. I am sure you will be fitting a 95, recommended by the book for maximum speed!

The mechanical and hand oiling systems are plumbed independent. The hand pump it piped directly into the top of the sight glass on the timing cover, and was not fitted with a tap. I would have to pull the pump plunger out Wed. when I get back home, but for some reason I believe that it is designed so that the entire contents of the oil compartment can not drain down through the sight glass, but only the charge of oil in the hand pump itself. In fact it would have to be that way as it bypasses the mechanical pump and goes directly to the sight glass.

There is a tap fitted to the line feeding the mechanical oil pump, since this draws off the bottom of the oil compartment. It then too passes to the sight glass via internal passageways. The oil exits out the back of the sight glass, and via a tube to the base of the front cylinder, and through a non-return valve. All the oil for the engine passes through via the front cylinder; there is no feed via drillings in the crankshaft as on the 350EW.

For touring work ignition timing is 45 degrees BTDC, full advance. For speed work 50 to 55 degrees was recommended.

Valve timing:

Inlet open 15 degrees BTDC
Inlet valve close 55 degrees ABDC
Exhaust valve open 51 degrees BBDC
Exhaust valve close 15 degrees ATDC

If you flywheel has not been skimmed, 7/8" around the rim represents 10 degrees aproximatly.

Valve lash is checked when hot.

Inlet 0.005 inch
Exhaust 0.006 inch.

-Doug

[Ian]

Hi Doug - thanks for the info. Re the carby my guess is the throat on mine is the 350 size - definitely less than 3/4" - should I bore it out ? It does have 123-5 on it so correct body.  Also, mine doesn't have a main jet - just a needle jet per attached pictures. How should the main jet work ? Should this one not have a needle at all ?

What does the main jet look like - similar to the needle jet on mine ? or short like an AMAC / AMAL one ? The current needle jet comes up about level with the gauze in the carby body. Is it just the size of hole in the side of the bottom screw ? (a 90 would be about .32")

[Doug]

Ian,

No needle, just a plain jet under a diffuser (fine wire mesh). There was a optional B&B carb with needle (automatic) offered in 1929 E/F29 handbook, but do not have the info in hand to check model and statistics for the carburetor. I am not sure, but I think the needle version of the B&B was around in 1928; just that Douglas was not offering it.

I was able to take some quick choke measurements before dashing off to the airport (waiting to board now.) The 350EW is 11/16 and the 600EW is 3/4 inch. You can bore out the body, in fact that is what I did. However that was years ago based on the recommendation of another 600EW owner. If someone else out there can confirm, that would probably be a good thing. The handbook does not give the choke size. Nor does the B&B handbook I have. It just lists four different models that year based on valve (slide) size.

-Doug

[Ian]

Hi - thanks Doug. Looks as though I may have an original 350 carb modified to have a needle - the wire mesh is there but has a hole in it for the needle to go through. If someone has an original that they could post photos off that would be great given Doug is on a plane ! I would like to see what the slides and the main jet look like. In the interim I guess I will go ahead bore it and set it up with the needle.