The 182 is a twin carburettor engine. you may have one mixture a little different

If you are using a IR gun, you may not be hitting the same spot on both cylinders?

Also, the glow plug is higher on the left cylinder than it is on the right cylinder. This could make a slight difference.

In reality, the resolution of your temp gun is probably more than the difference you are reading so you may actually be chasing your tail.

8 degrees is nothing.