1956 Chevy Exhaust temperature

[mike1954]

I was playing with my infrared thermometer.
I shot the temp on the exhaust manifold where it meets the head. One bank was a little hotter than the other. Did not seem like that big of a deal. The number one cylinder and the number eight cylinder were a lot cooler than the rest. #1 305 deg, #3 544 deg, #5 566, # 7 531 # 2 453 deg, #4 468 deg, #6 420 deg, #8 240 deg.
I took the readings several times with similar result.
Engine was at operating temp. Seems to run ok. Has a little stumble off idle.
I do not understand the temperature variation.
Any ideas??