What's going on with this motor?
 

I did a DOD delete on a 2017 gmc with a 5.3 l83. After about a month of driving, small amount of smoke was noticed coming from the tail pipe. I remove the valve covers and discovered the valve springs on one side of the motor appeared to have oil baked on the springs and the driver side did not.. springs for cyl. 5 and 7 being the worse. The valve seals are also toasted at these locations. The spark plugs for cyl. 3,5 and 7 appeared to be discolored as if they got hot and turning the gold appearance of the spark plug base to a lite grayish color.
any idea of what could cause this??

As for the work done to the truck, ls7 (gm performance) lifters, new trays, new brian tooley springs and seals. Texas speed cam, new ngk spark plugs, lingenfelter dod plugs and vvt lock out. Also long tubed headers installed.
truck was also tuned, there are zero codes (CEL), The fuel trim for that side are higher, however the tuner doesn't seem concerned after asking him about it. I did a comparison test of cyl. 5 with results around 210
https://cimg8.ibsrv.net/gimg/ls1tech...1a4cf1e6ae.jpg
These are arranged how they came off the heads,

It certainly got hot on that bank. Was there ever an issue with the coolant system at anytime?

No issues, othere then the motor noise associated with bad dod lifters

Even now the truck doesn't run hot, also the exhaust temp (at the header near the head) are the same, cyl. 5 might be a 50* higher difference.

How much do you want to bet that the head gasket was flipped on that bank?

It's possible..Pretty evident the valve seals weren't doing their job up front on that bank and the oil looks cooked to me.

Wouldn't this cause over heating issues, amongst other issues?

I agree, the cause seems to be unknown

Here's the thing: ONE half of the engine seems to be running too hot.

I'd be willing to wager that yes, the engine was running hotter than normal, but you didn't realize it because of the factory gauge strategy.
Factory gauges on these trucks ARE NOT ACCURATE. They go to the middle of the gauge (215 degrees) once they get to about 180-190 degrees, then stay there until about 225-230. I've watched this on a scanner.
Your gauge was probably reading the same level, even though the engine AS A WHOLE - at the thermostat outlet - was probably running about 15-20 degrees hotter.
But that one bank was getting a lot hotter, and it was hotter towards the rear, which is exactly what would happen if the gasket was flipped.

If both gaskets were flipped, you'd have overheating issues pretty quickly.

If this is the case, I'd be really suspicious of the cylinder head/ block surfaces.

that does make sense, we did also use HPT to monitor engine temp, as well external temperature "gun". I will look for the location of the tab on the lower edge of the head gasket, to see if indeed the gasket is flipped..

It looks like you had a ton of oil collect in that cylinder head, these engines aren't the best for pull over performance. Did you do any work to the heads when they were off? A flipped head gasket could explain the issue, or there could have been some holes that werent manufactured correctly........we all know that could never happen. :)

Hows the PCV system?