* Camshaft sprockets: The camshaft sprockets have two marks each, one for the intake valve and one for the exhaust valve. The intake valve mark is a small dot, while the exhaust valve mark is a small line.
* Injection pump sprocket: The injection pump sprocket has two marks as well, one for the fuel injection timing and the other is the engine stop timing.
* Front cover: There is a pointer attached to the front cover of the engine. This pointer must line up with a mark on the crankshaft pulley to set the engine to top dead center (TDC).
To install the injector pump, follow these steps:
1. Remove the valve cover and the timing belt.
2. Turn the crankshaft until the TDC pointer is aligned with the mark on the crankshaft pulley.
3. Install the injection pump so that the injection timing mark on the pump sprocket aligns with the mark on the camshaft sprocket for the cylinder that is at TDC.
4. Install the timing belt and the valve cover.
5. Start the engine and check the timing with a timing light.
Note: The injection timing for the Isuzu DA640 engine can be adjusted slightly to improve performance. Adjusting the timing requires special tools and is best left to a qualified technician.
