You can use a technique to set injection pump timing without the TDC mark, which is through the valve. In the paragraphs below, I will explain that in detail.
Under normal conditions, there is always a TDC mark on the flywheel, timing gear or other places, depending on the manufacturer’s design.
But in case the TDC mark is no longer visible, or you can’t find it, then this article will help you to set your injection timing even without the TDC mark
The initial action you must take is to remove the valve cover. If the valve cover is together, you can remove it wholly, but if it is a single valve cover, you can remove only the cylinder number 1 and 6 valve covers.
It would help if you disconnected your battery terminal so that mistakenly the engine would not rotate suddenly.
You can use a socket or a wrench to rotate the engine manually. You need to rotate the engine until valve number 1 is closed, both the intake and exhaust valves.
Then your number 6 cylinder valves are open at the overlap position.
But if it is 4 cylinder engine, then you are to use cylinder numbers 1 and 4. But in this example, I am using 6 cylinders, so I am using cylinders 1 and 6.
At this, your engine is at TDC; even without the TDC mark, you can rest assured that your engine is at the TDC.
To set the injection pump, you need to look for the injection pump timing. Some injection pump has a timing gear driven by the injection pump. The timing mark is usually on the gear.
To ensure the injection pump timing and engine timing, I will advise you to remove the timing cover or the front cover, which will give you adequate access to the timing gear.
After removing the timing gear, you can set your injection pump timing.
But if the injection pump does not have a timing mark, you can still set the injection pump timing.
Since you have gotten your engine TDC, you need to manually rotate the engine Injection pump until the number one is about to inject, then install it.
In some rotary injection systems, there is a key that you will use to lock the injection pump so that it will not rotate away from your setting until you install it.
If you can follow the above prompt, you should be able to set your injection pump timing without the TDC mark.
Your valve will give you an accurate TDC setting which is accurate enough to start your engine.
I hope you enjoy this simple explanation of how to set your injection pump timing without the TDC mark.