Inliners International Forums General Discussion Engines Mixing Lump and Non Lump Ports and Other Head Stuf

One reason why the center pair of cylinders does not always run richer in an L6 is that the long rotation delay for the 1-2 and 5-6 pair produces a stronger vacuum signal than the "balanced" 3-4. Jaguar compensated for this in the XK-E with slightly richer jetting in the 3-4 SU.