I am doing a swap from 2.0 to an AAZ and do not have a bell housing to mark TDC. I have everything lined up without a reference for tdc on for the fly wheel. Still have the Jetta fly wheel on it. What Im looking for is a way to reference something on the block to set TDC.
Thats a challenge. One way to go about it get a degree wheel from a hot rod shop and attach it to the crank. Line up to the existing flywheel mark, then turn the crank the appropriate degrees(7 degrees?) to back figure the offset out and make a new mark on the flywheel with a good paint marker.
The key/notch on the crank snout will be at TDC as referenced from the oil pan but hard to measure that with any accuracy
What are you trying to do, make the correct TDC mark for viewing in the bell-housing once that is installed? Or are you trying to find TDC for some other purpose prior to installing the bell housing? If the latter then use one of the many methods for finding TDC that have been outlined in various prior threads. My personal favorite is using clear hose in the injector or glow plug hole combined with liquid to see when the piston is ascending/descending and the exact point of transition (TDC). If the former, then I'd wait until the engine and bell-housing are mated and combine your favorite method of finding TDC with a hammer blow to a punch through the bell housing hole.