I noticed yesterday that the car was running a little rough... thought i should see what it could be when i got home. Lo and behold the car died in the middle of the normanby fiveways (lucky it was late or there would have been heaps of traffic)

got towed home. Thought it was the points, so had a look and changed them. the sparkplugs seem alright, all wires are connected, battery is ok. Still wont start.
It sometimes gets to chugging stage, but that doesnt last long. Just tried to start it again now and it wont even chug and a strange popping sound comes from the hole that the red arrow is pointing to. (i have the pdfs for the dcn, but they dont show the 40dcn and therefore i cannot locate that hole to find out what it is)

anyone have any ideas what it could be? Any help or suggestions are muchly appreciated.

(all this just has to happen the day before i need the car to get to exams.... isnt that always the way!)

i cant see those screw exactly in the Haynes manual (yeah only DCNF's) but they would be darn close to where either your mixture screw or air bypass screw would live.

There "should" be exactly the same hole on the other side of the carb
Have a look

See anything different???

Has one of these screws fallen out???

The good news is that 99% it will be a tuning problem
Missing screw or blocked idle jet.
Cause you are running only one carb a blocked idle will knock out 2 cylinders.

Do you know where the idles are???

it has the same hole on the other side but that also has no screw, and the idle screw is on the other side there is only one.

I wish I lived closer to come and help out. I ain't a genius but two heads are better than one.

Sorry I got no solutions, just check all your vitals, but it sounds like you know what you are doing there. Check your condenser, maybe even get someone to block that hole with a finger while you try and start it.

Good luck Starbuggy!!

Do you know where your mixture screws and air by pass screws are???

Is there thread inside these holes???

:alien

knowing nothing about the dcn or dcnf I would say it would either be a air bypass jet hole, or it is a hole left over from machining the internal ports, and should normally be blocked off. Try covering/blocking it with anything and seeing if it starts.

there isn't any thread in them, they seem to be a inlet or outlet for something. the hole as far as i can see moves to the left after 15mm. i know where the mixture screw is but not the air bipass screws are. i don't think there are any. where is the best and cheepest place to get the webber checked out in brisbane??

cheaper webers don't have air bypass screws. They might be ports that should be blocked. Try blocking them.

found the air bypass screw, its near the float at the back, there seems to be more oil than usaual around the air filter base??
could the reason its not starting be the ignition coil, as it turns over but does not fire, and when it did it took a long time ( holding the key on) to start, the idle was very rough, as if it was only firing on a few cylinders??

found the air bypass screw, its near the float at the back, there seems to be more oil than usaual around the air filter base??
could the reason its not starting be the ignition coil, as it turns over but does not fire, and when it did it took a long time ( holding the key on) to start, the idle was very rough, as if it was only firing on a few cylinders?? noticed small amount of vapour or smoke from the oil filler when i try to start it.

It does have fuel in the carb? right.

I ran out of fuel on the weekend, sounded like that too, chug chug, stop!

Ignition ON, take dissy cap off, turn engine so points gap is closed. With a small insulated screw driver, open points, taking not to short out aginst anything with screwdriver shaft. Should have fat bluish spark between points when opening. All well here? Ok then put cap back on, remove a spark plug lead and hold about 5 mm from a clean earth point, rotate engine: should have fat spark there... that should give you satisfaction that the ignition is ok.
Then start looking for vacuum leaks and fuel blockages. My guess is that the idle or main jet in carby is blocked. Had that happen once and had to drive 80km by continuously pumping accelerator and using fuel from pump circuit to get home. Has a painful right ankle for days!