Well, my friend's 1987 325ic had a blown head gasket, we took everything apart, degreased the whole thing, replaced the head gasket as well as all the other gaskets and seals, drivebelt and tensioner, and new bosch platinum spark plugs and oil filter (mann). The engine cranks hard and healthy but it wont start. Any suggestions would be appreciated.

Note: I previously replaced the drive belt on my 1991 325ic, so as far as I know I did not mess up the timing, I had both at TDC when I took the old belt off and I didn't turn the crank so hopefully that is not the issue. Would there be a horrible noise if it was a timing issue (like pistons hitting valves, etc)?