Where is the engine timing mark on an Chevy Astro 43L?

The Chevy Astro 4.3L (specifically the Vortec 4300) engine's timing mark location isn't easily described in a single sentence because it depends on what part you're looking at (crankshaft or camshaft) and whether you're using a timing light or the timing cover. There's not a single, universally obvious "mark."

To accurately find the timing marks, you need a repair manual specific to your year and model Astro van. The manual will have detailed diagrams showing the location of the timing marks on both the crankshaft and camshaft, as well as the proper alignment procedure.

Generally speaking:

* Crankshaft: You'll find a mark (often a notch or pointer) on the harmonic balancer (the pulley at the front of the crankshaft). The repair manual will tell you where this mark needs to align.

* Camshaft: The camshaft may have marks on the gear itself, or a pointer on the timing chain cover that aligns with a mark on the chain or the camshaft gear. Again, consult your manual for precise location and alignment.

Without a repair manual, attempting to adjust the timing is risky. You could seriously damage the engine. The location of the marks varies slightly between engine variations and years. A Haynes or Chilton manual, or a factory service manual, are essential for this job.