Pilot jet adjusting screw

[Jurassic]

I recently bought an Amal mk2 repair kit from Burley. I didn't need it all, but it was a better price than bits bought individually. I thought I'd fit the bright new shiny pilot air screw in place of the "original?" well used existing screw which produced a reliable tick over at about 1250 revs set 11/2 turns out. Trying to set a good idle with the new screw was achievable only with it screwed fully in. Comparing them side by side showed that they varied greatly on the taper. Measured at the tip of the taper gave a reading of 2mm diameter for the original, and 1.5mm diameter for the new. This difference would give a vast change to the air/fuel mix. I have been in contact with the technical department at Burley/Amal querying whether there is more than one version of screw. They are only aware of the 2622/128 part number, and have been machining to this for the last 15 years. The drawing of this part specifies a taper of 10 degrees. Photographing both side by side and measuring the taper, gives my original at 10 degrees, and the new a bit steeper at 10.75 degrees. Of course depending on machining tolerances it could still be within limits. Burley are investigating. However if you've had to change the pilot jet from standard (25 in the body for a 34mm) it may be worth looking at the pilot screw.
Images posted below

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