Webcon UK Ltd

Steve Williams · New user Joined: 09 Dec 2007 Posts: 8

For a straightforward stock 2.0 litre Zetec Blacktop engine on DCOE 40s, lightweight flywheel and wide bore 4 into 1 exhaust:

DOCE 40s

Chokes: 36mm
Mains: 130
Emulsions: F2
Air Correctors: 160
Idles: 65F2
Pump Jets: 40

MartinEva · Site Admin Joined: 03 May 2007 Posts: 9

Steve. How does it go with the 40's? We use 45's in our kits and modify with a 5th progression hole to aid driveability.

Steve Williams · New user Joined: 09 Dec 2007 Posts: 8

At the moment I am still experimenting to get the best driveability. This combination is close to perfect, excellent pick-up, no hesitation when full throttle is applied at 1,500 rpm in 5th. gear, no stuttering, clean response anywhere from 2,000 rpm up. No spitting back on the overrun, no lean cuts, easy starting. At the moment the throttle response is carefree, whereas when I first acquired the car it was nerve-wracking. I never knew if it was going to cut or stumble on acceleration - not a good habit for a Westfield.

Just a very slight hesitation at a particular throttle/rpm combination, but this is hard to reproduce. I think I will need to put it on a rolling road to sort that one out, but I'm more than happy with it on the road.

My DCOEs have the standard 3 progression holes. I suspect I could reduce the size of the idle jet if I had one or two more drilled, but I am loathe to change things now they seem to be sorted.

My current idle jets started as 45F9s, but I have drilled them out to about 65F2. Once I've settled on the ideal size, I'll measure them with a vernier micrometer and get the closest matching original jets.

I have yet to check the emissions and consumption, but I'll need to do this on a rolling road with a gas analyser.

Hope this helps.

Steve Williams · New user Joined: 09 Dec 2007 Posts: 8

Martin,

I have been driving my Westfield with the jetting as given above, but, whilst the driveability is excellent, the fuel economy is pants - in the order of 20-22 mpg. Bear in mind that this engine will do 30-35 mpg in injected form in a Mondeo, which is 2 1/2 to 3 times the mass.

I find that the exhaust is very sooty, which also indicates an overly rich mixture. The question now is how best to modify the jetting to improve economy whilst retaining the driveability?

Initial mods will be to increase air corrector size back to 180 and emulsions to F16 or F9. If these do not do the job I will need to consider the 5 progression hole mod. Can I do this myself? If not, what is the turn-round time and cost?

Beyond that, if Webcon now have a sale, perhaps an exchange of the current 40s for a pair of 45s pre-drilled with the 5 progression holes and 36mm chokes would be an option?

If this is not economic then maybe it's time to say sod it and switch to injection.

Steve Williams · New user Joined: 09 Dec 2007 Posts: 8

More on this saga...

I recently serviced the DCOE 40s with a Weber service kit, and reset all the jets. I then had to reset all the jettings from scratch, but it was a very useful exercise.

I replaced the idles with the original 55F9, and set up as follows:

1. Synchronised the butterfly valves visually through the progression holes.
2. Opened idle mixture screws 1 1/2 turns.
3. 1/2 turn on the throttle stop screw.
4. Started engine.
5. Adjusted idle to @1000rpm using idle mixture screws.
6. Adjusted synchronisation between carbs.
7. Reduced idle rpm by adjusting throttle stop screw.
8. Raised idle by opening air bypass valve.

Ultimately I had the engine idling at 900rpm with the butterflies fully closed and only the air bypass valves supplying air. This entailed about 3 turns on the air bypass valves, and the idle mixture screws are about 1 turn open.

On very rapid throttle opening with no load, there is a hesitation, but this never occurs under load on the road.

So now I have restored the fuel economy whilst retaining the driveability. I think that originally the throttle stop screw was opening the butterflies too much at idle, and this was bringing the progression holes in too early. This adjustment appears to have solved that, but there is still some fine adjustment to be done I am sure, but it will take a rolling road session to resolve.