No compression and no spark?

I need help with a problem. I have a 90 300zx non turbo automatic. I was stopped the other day at a red light. I left the light normally and my car just stalled out. I was only doing about 10 or 15 mph at about 2k rpm's. I pulled over and tried to crank it but I got nothing. I sounded like the gear on the started was stripped just a winding sound but all of my belt where still turning. When I got it home I checked everything and found out I wasn't getting any spark but I was getting fuel and also my timing belt was loose. When I checked the timing I found out that the bolt on the auto tensioner pulley had broken in half. The belt was still in perfect condition and nothing had happened to anything else. I replaced the bolt and put the belt back on and made sure all 5 marks for the timing where lined up. After I put everything back together I tried cranking the engine but with the same results. The engine will turn and the crank turns including the timing belt but it still wont start. I checked to make sure the pistons are going up and down and they are I checked the left side came through the oil opening and it spins. Then I did a compression test on the four front cylinders and I'm getting no compression at all I mean the needle doesn't even move. I know the gauge works fine because I checked that. To make a long story short I'm showing no compression at all and getting no spark at all. I swapped the engine about 6 month's ago with a 94 Infinity J30 with 64'000 miles on it and up until now it was running strong, no hesitation no knock no noises at all. There was no sign that anything was going to happen and when it did I didn't hear any noises from the engine. I know its an interference engine but I would think if something messed up inside I would have heard a noise or that I should show some type of compression. Please I need some insight on this. This sucks a lot. I would appreciate some help.

No compression at all would be indicative of something drastically wrong with your valvetrain. It doesn't make sense though that the engine would still turn freely if the valves are sticking open. Mate, I'd take the head off so I can see whats going on. Chances are you're gonna hafta get the head worked anyway,

The spark is a little odd though, you sure you're grounding the spark plug when you're cranking the engine? That still to this day gets me when im not thinking straight :)
Anyway, if none of the sparkies are firing, could be the power transistor, could be the ecu. It doesn't make sense that they both screw up at the same time though. I'll sleep on it and see if i can figure out what could have happened.

-Mike

I'm glad Mike is here... 'cus I would have nothing to say! Sucks about your Z, Damar! I always check out what problems everyone is having 'cus it may happen to me! I also have a '90 NA with AT and have had alomost every problem in the book of what can go wrong with a Z... but never that! Good luck!

Mike thanks for your help I do appreciate it. I took everything apart again and the two cam gears on the right side spin freely. I'm not supposed to be able to turn them by hand all the way around. The gears on the left side are still tight but no compression. I'm thinking maybe most of the valves on the right side just went on strike and stopped liking me. So I'm just going to take the heads of and check it out. I got a couple prices on head work and found the cheapest to be $400.00 for both, $60.00 to resurface both, $70.00 to pressure test both, and $10.00 for each intake valve and $13.00 for each exhaust valve. So the conclusion I came up with is just to buy the valves and do it myself. It wont be fun but hey I'll save a lot of money. In the mean time I'll just drive my other vehicle but it has a 454 and only gets 4 to 5 miles per gallon. I'm just in a no win situation. Money, money, money. There is still one thing I don't understand. Why am I not getting any spark is it just bad luck that both happened at the same time or does the damaged to the heads have something to do with it. Oh well I guess I'll find out. Thanks.