Weber 32/34 DMTL Fuel Starvation/Flat Spot

Ok so been on this for nearly 3 weeks now and can not figure it out.
Mk1 Clipper with 1.8 Auto engine and box in it and a 32/34 dmtl weber (virtually new)

Car runs and idles perfectly, smells all good so all seems well.
Whenever i try and accelerate between 850 (approx idle) and 2000 rpm i get a massive flat spot which pretty much cuts the engine out.
Seems to me like a fuel starvation problem.
Bypassed the fuel seperator to see if it was that, no difference.
Had the timing checked, its bang on. Dizzy runs a constant advance system as far as i can tell? Works fine and timing marks all line up so cant see it being a timing issue.
All vacuum pipes are connected right, the base plate is near enough new and in good condition and the carb itself is in generally mint condition.
Someone has mentioned about the accelerator pump maybe being an issue? It seems to work pretty much as it should, although there isnt any fuel coming from the jet on the first bit of my acceleration? possible problem or?
There is a tiny slight leak on the exhaust manifold because when i pour water over it the engine dies down a little bit but i dont for one minute think its enough to cause the problems im having?
Ive got pretty good mechanical knowledge and have had no luck whatsoever with this, ive gotta be missing something obvious?
I remember the Pierburg having a similar issue which i think i resolved by adjusting the mixture but im 95% sure the mixture and idle are fine on this at the moment?

HELP Alex

pictures:

Is the flange that the webber sits on new or make sure there is no air getting in.

Timing could be out, is it set via a timing gun? I did the same and my car drove trebble, dogging down when pulling away you had to rev it go to get going.
Run the car and advance the timing (losen clamp and turn the dissy anticlockwise, you might need to change the tick over as well) till the car starts to "pink" under load (30 mph and slowly flooring it in 5th) Will take a few attemps to get it right, start, stop get out turn the dissy again drive a bit, etc.
If you make where the dissy is to start with if it does not work you can always go back to where it was.

Another idea…

Spotted you have a swirl pot fitted..

http://sciroccoregisterforum.co.uk/carforum/viewtopic.php?f=12&t=15397

I bypassed the swirl pot/vapour seperator last night and had no luck still, no difference.
Really running out of ideas !

Have a play with the timing (moving the dissy), I wished I never borrowed a timing gun as I wasted a couple of hours changing the timing to "by the book" then back to how it drives better.

Cheers for the ideas mate. I will have a play with the timing as a few people have suggested it too. Its set bang on the marks using a timing gun but I could always try advancing a bit more and see what happens.
Cheers 
Alex

As I said mark it up first, take a 13mm spanner losen the clamp, advance timing, nip the clamp back up, give it a try, becareful of the fan kicking in when working on the dissy clamp…
Let us know what happens..

Ok so had a play around with the timing this morning and cant say as it made a massive difference or almost any.
I did find that with the airbox off if i use my hand to cover the top of the carb almost fully then the problem pretty much goes away which indicates to me its deffinitely an air issue somewhere?

Have a read of this, could be the rubber gasket the carb sits on has a split in it.
http://vwgolfmk1.org.uk/forum/index.php?page=topicview&id=big-block-carb-engines_2%2Fstuttering_2