Just put a weber and electric fuel pump on the freshly rebuilt engine...
As soon as I start the car it just revs wildly with no sign of stopping so I have to switch off the car!!!
Can anyone help??
The mixture has been played with and so has the throttle screw.

idle screw screwed out way too far, throttle stuck open, or massive air leak through the manifold

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did I tell you that I won a trophy?

Sneaky air leak from exhaust gasket?
Covered the ram pipes slightly and she ran perfectly.......

Can the soft mount plates be done up too tight?
Could the engine breathers have anything to do with it?
The butterfly valve is closed and it just wants to rev to 5k and beyond!

Is the Weber still touching the body like yesterday, if so it's still sucking air at the bottom of the manifold gasket.
Actually since you did it up all tight before when it was kicked up, you probably now need a new gasket on there... it'll be distorted and leaking.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Got a hands clearance under the rams...Sledge hammer was enjoyable.
Is it worth trying to gasket sealant as a test before getting a new gasket??

Yes but not ordinary gasket sealant. Black silicone gasket maker will work, or Loctite 515 - I have used that a few times when I've taken the Weber manifold off and it's damaged the gasket surface.

It's probably leaking from the top now, not the bottom...

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Alright, I will try tomorrow and hope for the best!
If not, is there anywhere I can take it to sort it out? Ivan?
Need it running in the next week or two for my rego!

Is it a brand new weber? Or an oldschool webber?

If it is a new weber I would say the problem is right there. They are much more complicated than the old webbers. I bought a brand newy for my mini and kept reving up and wouldn't drop the revs quick enough. Couldn't tune it.

Swapped it with a mates old webber and It was fine.

Have you made sure the mixture/airbleed (whatever they are called)at the front of the webber are not adjusted way out??

But does sound like an airleak.

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Yeah its an old one I've rebuilt and rejetted... Did it myself which may be the problem to start with.....
Seemed very straight forward though?
I did put in new mixture screws so maybe I'll have to keep playing with them.

This is killing me!! I just want to drive it!
Could the soft mounts be giving me any trouble? Do them up stupidly tight?

Soft mounts don't need to be tight when new.

Personally on my road car I use a gasket instead, never had a problem in 20 years since I flung the old hard `soft' mounts.
But I run a 45 Dellorto, they may be less sensitive to flooding or frothing or whatever folklore says the need for soft mounts is.

[edit] for your initial idle mixture setting, screw both mixture screws in until they seat lightly then screw out 1-1/4 turns.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Could the soft mounts leak if they are TOO tight?

Not if new. But then they won't absorb engine vibration, which is their primary purpose.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.