Hitchcocks Forum

Hi chaps, I need some help on setting the carb on my WD/CO. I have the correct carb 276AC/1A set up to the correct spec but for some reason it chokes the engine when it runs. There are plumes of black smoke from the exhaust so is running rich but I can't get it to run right untill I turn the petrol tap off. When the tap is off, within about 15 seconds the engine picks up and runs much better untill the fuel in the bowl has been used. I have no leeks apparant and at first I thought the float needle wasn't seating so I stripped it and rebedded the needle in with some metal polish. I checked the needle was seating by filling the bowl with petrol and it was perfect with no petrol escaping. So does anyone have an idea? I'm now thinking I better check the tickler isn't holding the float down or somthing like that.

Cheers, Chris.

From what you say the fuel level is to high,so does the float float and is the float setting/shut off position correct?
Also does the needle valve (operated by the float) shut the fuel off in this position?
Also what`s WD/CO ?
I`m new on here.

It took me ages to get my 276 working properly on the 51 Bullet but the major breakthrough came when I realised that the major issue was that the jet block and the body weren't mating closely enough. The problem arises when the big nut at the bottom of the body is over tightened and this crushes the bottom of the body but bells out the area where the jet block and the body meet. This gives the impression that the jet block is a tight fit in the body when in fact it is only a tight fit at the very bottom. A bit of engineer's blue will show you if there is a gap. The result is typically a carb that runs rich and there is no significant control from the air screw. The solution is to carefully scrape the bottom of the carb body to parallel it up and then to shim the jet block across using paper so that the holes that coincide with the body are a tight fit. This will get the carb working as it should again and allow adjustment at the air screw. This presumes of course that the float bowl isn't flooding but if it is there will likely be petrol pissing out all over the show.

Also look back on here to " leaking amal 276 carb" created on 24th Sept.

Another thought, do you have the correct float bowl? The neck that joins it to the carb can be specified at several different angles to suit down draught applications and other different angles of installation. I think yours should be completely flat, possibly coded AO (angle 0 degrees???) but they are not always stamped.
REgards, Mark

Thanks for the replies chaps, there is only one groove on my float needle for the float to lock into so I cant adjust that side of it. It seals tight when I do it manually but I think I need to go turn the taps on and see if floods and leaks. I don't think there is a issue with the jet block because when I shut the fuel off, it will run off the contents of the float bowl quite sweetly for about 40 seconds before id starves. The float bowl is the correct 1A bowl, I have about 5 others I could swap out for a trial. My other thought is that it maybe the union between float bowl and body, the parts ID states a shallow union which I think is whats fitted, but I could be wrong as I dont know how many depth unions were produced.

I'm going to have a search for the leaky carb post jaffa90 mentioned.

Cheers, Chris.

Sorry, I forgot to mention that the WD/CO is a Royal Enfield model WD/CO, its a Model CO built specifically for the war department in WW2. My CO is actually from a cancelled contract so is technicaly a civilian Export model CO.

The check for my diagnosis is can you make the carb too lean by unwinding the air screw? If there is no proper connection then then the idle screw will have little or no effect until it is completely out of the body then the motor will stall. If this is the case then you should check the.jet block / body fit. Remember the issue is with an airway not a fuel way so the fact that the bowl will run out is not relevant.