Please help and confirm what I have done. I have been given a no go 1990 240 wagon it was a broken belt, I removed the head to recondition it. I now have two options for finding tdc on the flywheel one is correct and the other will be 180 degrees out. I have removed the bottom reinforcement casting and watched the indents1 from the engine side go round, I have visually placed them more or less level with the ignition timing hole and then nudged no.1 piston up/back to tdc. On this stroke i intend to rebuild, is this correct.

If you want to find TDC on *ANY* engine - both valves are closed while the rotor is pointing towards cylinder #1 ..... the compresion cycle ..

It usual to reassemble the motor with No#1 on TDC before you fit the head, and NOT rotate it until the cam and cam drive is installed. There are, however, 'too late for that' cures, see below:

There should be marks on the front pulley, with a timing pin or scale to use a timing light, OR a replaceable bung over the flywheel and marks on the flywheel corresponding to TDC & 12deg BTDC.
or
TDC rotor method as given is imprecise, you use of a CLEAN, SOFT tool feeling for TDC via the plug hole or other visiual/touch means if you must, as long as you remember that the insert MUST NOT jam as the motor rotates.

The rotor pointing to No #1 is useful only if dizzy still in motor and connected thru' to the crankshaft, otherwise, you can nominate which position on the dizzy is cylinder #1 and go from there, thus being any multiple of 90deg error as you choose.

The EFI allows this without harm providing there is NO pickup synchronising the No #1 cylinder on the dizzy cap. IE Cap will HAVE to have either NO small turret on top near an output turret , or has small turret, but has NO connection in it and is NOT wired out to the rest of the ignition system as a sychroniser for the injectors to sequence individual injectors. Most older Bosch systems ( Vis: LH 2.2) use a common injector pulse every 360 degrees to all injectors, Imperfect, but adequate for most modest purposes. Only later, hi performance systems (or 6 cyl?) would have bothered with the even more expensive sequencial injector operation-them needing the synch pulse from the dizzy.

Even today, both ideas are in use, cheaper, low performance vehicles tend to use the common pulse systems, and vice versa. In the early days of EFI in Oz, we even had 6 cylinder cars with just 1 injector on the manifold! 3 guesses how good that was.

Yes I know that! however the head is off!!! It's the position off the flywheel signal pin which I cannot see' as the gearbox is on, so looking from the front towards the back of the flywheel how do you know when you are on tdc as regards the signal pins. I can see no mark indicating tdc when looking down behind the block after removing the inductive speed pick up sensor. There are two chances! as I said, if you rebuild the top end and you are 180 degrees out then it will never start as the signal pins will be sending the wrong information to the computer! on the wrong stroke The distributor is also out of the engine.

I'm sorry !I have just been out to the garage and hand turned the engine over by the crankshaft pulley and yes the white spot i painted on! is visible again. so providing install the head, belt,and dist. on tdc on no.1 everything should be okay.
Thank you

Congrats!!