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A few days after I purchased my TR3 in 2009, my mechanic gave me some helpful pointers on how to set the mixture. One thing he said, which went in one ear and out the other because of my inexperience, was "Always remember that the carb you are lifting is not the carb you are checking. If you lift the front, you adjust the rear."
In the ensuing couple of years, I have read and been told by many people that when you adjust the mixture, you lift the pin on a carb and you turn the adjusting nut ON THAT CARB.
But recently, I was reading a manual for a 1954 XK 120, with H6 SU carbs, and found following:
"Next check the mixture strength by starting the engine and raising the lifting pin of the FRONT CURBURETTER. ... If...
... (a) The engine speed increases and the engine continues to run at increased speed, this indicates that the mixture strength of the REAR CARBURETTER is too rich....
... (b) The engine speed increases and the engine then stops, this indicates that the mixture strength of the REAR CARBURETTER is too weak.
... (c) The engine speed increases momentarily and then decreases but the engine continues to run somewhat bumpily, then the mixture strength of the REAR CARBURETTER is correct.
Repeat the operation, lifting the REAR CARBURETTER piston and testing the mixture setting of the FRONT CARBURETTER."
In other words, When you lift the pin or piston on one carb, it is THE OTHER CARB THAT NEEDS ADJUSTING.
Any thoughts on this procedure?
In the ensuing couple of years, I have read and been told by many people that when you adjust the mixture, you lift the pin on a carb and you turn the adjusting nut ON THAT CARB.
But recently, I was reading a manual for a 1954 XK 120, with H6 SU carbs, and found following:
"Next check the mixture strength by starting the engine and raising the lifting pin of the FRONT CURBURETTER. ... If...
... (a) The engine speed increases and the engine continues to run at increased speed, this indicates that the mixture strength of the REAR CARBURETTER is too rich....
... (b) The engine speed increases and the engine then stops, this indicates that the mixture strength of the REAR CARBURETTER is too weak.
... (c) The engine speed increases momentarily and then decreases but the engine continues to run somewhat bumpily, then the mixture strength of the REAR CARBURETTER is correct.
Repeat the operation, lifting the REAR CARBURETTER piston and testing the mixture setting of the FRONT CARBURETTER."
In other words, When you lift the pin or piston on one carb, it is THE OTHER CARB THAT NEEDS ADJUSTING.
Any thoughts on this procedure?