Taking advantage of the Edelbrock timing set's three-position crankshaft gear, we can restore proper camshaft centerline specs by ignoring the zero-offset (straight-up) keyway, as marked by the circular symbol, and installing the gear and chain so the square symbol aligns with the cam gear instead. The square symbol retards cam timing 4 degrees, while on the other side of the neutral round symbol, the unused triangular alignment mark yields 4 degrees of camshaft advance. After matching the square mark to the cam-gear dimple, a subsequent intake centerline check reveals 107.5 degrees. We're advanced 0.5 degree over the Isky spec. We could fine-tune the intake centerline and get exactly 108 by machining the three cam-gear bolt holes to accept 0.005-inch offset bushings. But frankly, the effort would not be noticeable, so we'll let it be. Once incorrect timing-chain installation has been ruled out, root causes of cam phasing discrepancies are machining variations on the crankshaft snout keyway, crank gear, timing chain, or cam gear or camshaft dowel and bolt positioning. Regardless, we're glad we checked it.