Head temp differences, How big is too big? Options

[lapuwali]

I recently fit a CHT gauge, and originally put the sender under the #4 plug. Readings were in line with what I've read here: idled at 300dF, cruised at 325-350dF, touched 400dF under heavy load (lots of long uphill grades here).

I moved the sender to the #1 plug yesterday, and the temps are as much as 50dF lower across the board. Idles at 250dF, cruise about 300dF, never exceeds 350dF even pulling up a long hill.

I expected a difference, but not 50dF (20%!) between heads. I'm running Webers, so it's possible I have completely different mixtures for each cylinder. I presume cooler head temps would usually mean richer? This would be in line with plug colors (blacker on the 1/2 head, tanner on the 3/4 head). Hmmm....

[lapuwali]

There were several holes left in the tin from the carb conversion done by the PO, including the large one for the FI CHT (no present), and the one over the oil pressure switch. I taped up these holes and moved my CHT sender to the #3 plug, which Jake notes should run hotter than the #4, which was running at 300-350-400 (idle/cruise/load) over the course of several days. This morning, the temps were 280/330/380, so assuming outside temp differences aren't messing with things (I really need a dual gauge...), it looks like doing that cooled things down by 20-40dF, depending on how much hotter #3 had been running compared to #4 before.

Not all that scientific, but at least I did appear to reduce the temps a bit.