Revs Rise As Brake Pedal Is Pumped.. Mi On Carbs..

[Stu 18]

Hi all,

 

Ive noticed of late that if i pump the brake pedal while stationary the revs rise up to around 2k then settle if i stop.. Its an Mi on carbs, with a colin satchel manifold with a servo take-off plumped in.

 

I considered an air leak, so bridged out the sunroof and such and went direct from the servo to the manifold which made no difference

[Cameron 16]

Sounds like an air leak in the servo, maybe a split diaphragm or something?