I am using the lifting pins on my SU HD6 carburetors to test the air/fuel mix and make adjustments. However, I read contradictory comments on test implications.
The original Jaguar maintenance manual says the results of lifting the FRONT carb pin gives information about the REAR carb mix, and vice versa.
By contrast, an article on the sucarb website says “the indications given by lifting a pin apply primarily to the carburetor in which the pin belongs and it is on this carburetor than any adjustment should be made”
Rattling around in my head is the conclusion that both versions are correct, with the two versions having different lift distances causing different results.
Lifting the carb’s piston only 1/32" simply leans out that particular carb a bit…but, lifting it as much as 1/4" …as some manuals suggest…reduces the venturi vacuum so much that this forces the engine to run on only the other carb. So, both methods can be used…you just have to adjust the appropriate carb depending on which method is used.