Neon stopped while my son was driving. Found that timing belt had broken due to a frozen water pump. Replaced pump and belt and reassembled. No start. Disassembled and turned cam 180 degrees. Still didn't start. Checked compression which was low and found used head. My question, if crank is at TDC how do I know the cam is at TDC or 180 degrees out?

 

you can check by using the compression guage , screw it in no 1 cylinder and turn crank while having the the cam lined up in its marks. , its either gonna be in the compression stroke or exhaust stroke , you want the compression stroke. but be aware i believe these motors to be interference engines wich means u may have already done damage . be careful not to bend valves trying to re time . so u may wanna just be very safe here and pull the valve cover and verify on no 1 cyl that both valves are closed and the marks line up for the cam , witch means you are the compression stroke then you should rotate the crank till you get tdc or compression from no 1 cyl.

 

If the belt broke while driving, there is a 99% chance the piston and valves smashed into each other.