I was going to check the timing on my 240K but the pulley doesnt have the pointer/mark so how do I know when it's on the right position?

Yes I do have a timing gun.

Are you saying that the pulley doesn't have any markings on it (usually notches around the outside of the front surface - sometimes painted, sometimes not. They can be hard to see) or there's no pointer to line up against the notches.

If there's no pointer, then you can make up a temporary one with a piece of heavy wire (such as a few inches off an old coat hanger). Coil one end into a loop and fit it inder one of the bolts on the timing cover. Then adjust the other end (which you have sharpened to a point - to make a good pointer ) so that it points at your pulley.

Now, set your engine to TDC. Do this by doing the following: with No 1 spark plug out, and both valves for No 1 cylinder closed, raise the piston to its uppermost position. Use a drinking straw down the spark plug hole to tell when the piston is at TDC.

With the engine at TDC, then adjust the pointer you have made so that it points to the TDC mark (I think there are about 4 or 5 marks. One is 5 deg ATDC, one is TDC, then there will be a few BTDC marks as well). Once you have set TDC, then you can use your make-shift pointer to set the timing on your car (obviously, pit the spark plug back, and make sure you haven't left any spanners attached to the crank pulley bolt or anything like that.)

Note that if done properly, this method is actually more accurate than the factory markings, which after 30 years of abuse can be inaccurate.

If it's the markings that are missing off the pulley, then ignore all of the waffle above.

HTH

Yeah my pulley doesnt have a pointer but I have the BTDC marking