Nissan Repair: 1986 nissan 300zx timing belt, nissan 300zx, oil pump housing

Question
We have a 1986 300zx that was making a loud noise from the front of the engine. After taking the timing belt cover off we found the tensioner was 90% gone and the belt was very loose. The care ran before we took it apart and made no engine noise except for the tensioner and belt flapping. We followed the haynes manual and made sure both cam gears were at the marks on the rear timing cover and the crank grear mark was alligned with the notch on the oil pump housing. We installed the belt with the alligment lines on the corrisponding marks on the gears. We adjusted the tensioner so that there was a 1/2inch deflection between the cam gears when pushed by hand. I also counted the belt notches between the cam gears timing notches and there was 40. I was told there should be 40 if installed right. I then hand bared the engine over 10-12 crank revolutions and slowly lined up the TDC marks. They were all on except the passenger side was off a 1/4 of a tooth wich I was told is normal. We then hand barred it over allot to chak and double check the the TDC marks always lined up every 4 turns of the crank. after installing the lower belt cover, dampner and pully's I hand barred the engine over 10-20 times until the to cam gears were in line with the timing marks on the rear timing cover. I also noticed that the 0deg mark on the pully (the last notch on the left looking at the engine) was in-line with the pointer on the timing cover. I barred over the engine for about 20min to make sure all marks lines up at TDC. The whole time I was barring the engine there was no indication of any binding. Also we made sure the the dist rotor was at #1 plug wire at TDC. After re-installing all parts we went for a start up. There was alot of clattering and knoking noise and it ran really bad and stalled. I Pulled the top timing belt cover off and went to hand bar it over and it was really hard to turn. We lined all the marks again and checked the dist and was at #1 cylinder it was also lined up with a little tab at the base inside the distributor. We checked the belt deflection and it was still 1/2 inch between the cam gears. We re-installed averything and tried to start again. Still ran bad with clattering / knocking noise from what seems like the passenger side of the engine and even tried to move the distributor to see if it would make a difference. Still ran bad and died. took all top covers off againg and barred over the engine ( Very hard to turn by hand now ) untill the cam gears/ Distributor rotor and crank pully's all were at TDC. I am at a loss as to what our problem is. If all timing marks are alligned what could be the problem.

Answer
Hi Donovan -

Have you checked the compression? Perhaps somehow the engine was turned when the belt was not aligned properly and the valves interfered. Taking a compression test will verify.

Please go ahead and do that, and get back to me with the results -

Thanks
aloha
calvin