Chevy 350, zero compression. engine not starting
Just received a rebuilt long block from a local mechanic. 1972 block, 96 vortec heads. hydraulic lifters, roller rockers. Prelubed it by using an old diff till oil came out of each rod. installed diff, and tried to start. not even a cough. checked compression in cylinders 1, 3, and 2, zero compression. pulled the valve covers and rechecked the hydraulic lifters on cylinder one by going to TDC and making sure both valves were closed. backed off till loose, tightened to zero play and then preloaded 1/2 turn. Also plugged in my air compressor into the spark plug hole using my compression tester adapter and heard no leaks. Any clues guys? Did the mechanic install the timing chain incorrectly maybe? How can I tell? arghhhhhh......