Timing chain was installed by myself (done 20 or so) so I'm comfortable that it is correct. Not my first engine rebuild so I am comfortable that all was assembled correctly. Rings were set as per the factory service manual, checked ring gap with a feeler gauge and filed for fit. Engine shop fitted the pistons and installed them on the rods for me.
Went to start the engine and it was blowing the gas back out the intake as well as pulling it in. I know hydraulics lifter should feel solid when working correctly but they don't bleed down when it sits overnight either.
The engine never even back fired. Has spark and fuel (another story with FITech). As I have stated it has no compression with the rockers on.