Is this a peirburg 2e3 carb?

[The Silver Surfer]

its off a 1.9 dg petrol 1980

[kevtherev]

yep it is

[The Silver Surfer]

cheers, I think this is what is making my engine rev like mad from cold.

[kevtherev]

yes it will.. there are three throttle positions for the idle speed on choke

[The Silver Surfer]

Do you think its he choke that is stuck on the cam.

[kevtherev]

the vacuum operated choke pull down unit will return the choke to it's proper position at operating temp.
the stepped idle speed is sprung independantly and works with the choke.
it's quite a complicated affair but when the carbs off and in your hand, you can see whats happening a lot easier.

with a cold engine depressing the acc pedal before turning it over sets the idle speed and the choke.
as the engine warms up, and the acc pedal is used, the idle speed drops to the next step down, then again, and then again.. eventually the butterfly closes the venturi to use the air bleed ..the choke progressively opens as the bi metal spring gets heated by the coolant and uncoils, allowing the idle speed to step down.
remember the choke richens the mixture, so an air leak will lean it out, raising the rpm where ever the butterfly is.
the idle speed step just saves you keeping you foot on the acc
mine revs at 1500 rpm if I do not touch the acc pedal, and as the engine warms up, it increases to 2000rpm

the pull down unit is now an obsolete item.

[The Silver Surfer]

is it hotwater that operates the choke. I thought I might have a lack of hot ware passing through the choke mechanism.

[kevtherev]

yes coolant passes directly through from the cylinder head via pipes

the bi metal spring can bust or it can seize