I had to replace my cracked 706 heads.(2005 silverado with 5.3) I found a set of reconditioned 243's and had .025 milled off of them. while I was in there I swapped out the cam for a comp 212/218. Got it all back together and got a BlackBear data logged tune. Truck runs awesome. But I get a pretty good puff of Grey/Blue smoke at start up and oil consumption of 1 1/2 quarts in a 1000 miles. The puff of smoke is random. Any Ideas what went wrong? No oil consumption before the swap. I went to change the pcv valve but it doesn't have one???

 

Could be a bad valve guide seal or a worn valve guide.

 

X2 Not all shops do good work when reconditioning.

 

Pull the plugs the dirtiest one will be where you oil is being used at

 

^ this
When you find the culprit, pull the valve springs and check the seals.