1987 BLAZER 5.0L WITH TIMING SET AT 0 AS PER SPECS VEHICLE WILL COUGH AND SPIT UNDER [...] TIMING TO 12 BTDC ENGINE RUNS [...] VERIFIED CAM AND CRANK TIMING INSTALLED NEW CHAIN WHILE THERE,TIMING MARKS LINE [...] OK .ONLY OPTIONS I CAN THINK OF OUR WORN CAMSHA... Login to read more.