Had an intake manifold leak on 5.7 Vortec engine. Pulled dist and replaced gasket between manifold and head. Now, It does not want to start. Have fuel pressure, spark at the plugs (checked with timing light and pulled plug to verify with spark plug) and have compression poofing out plug hole when we checked. Wanted to check timing to see if on the money but don't see how. Mark is on harmonic balancer but there is no place to match it to on engine. Belt system and mounts cover every thing up. I would assume timing is computer controlled but there must be a way to verify it. I could be a notch off when we put the dist back in. Suggestions?