I'll try and make a long story short. I converted a '95 Firebird to an '02 Firehawk with a complete donor car. I moved over everything, literally. In the process I (along with a friend who has been through numerous LS motors and is an auto mechanic for a living) put a heads cam package on the LS1 with 50,000 miles. The package was Torquer 2 112+2 (which we degreed another +2 after reading about numerous power gains on here), 5.3 heads stage 2.5 with dual springs, hardened pushrods 7.4", dual chain timing chain, ls6 oil pump and ARP rod bolts. We put the motor together at least 4 years ago, which I am sure has not helped the situation but its a project car.

On initial start up I read through numerous posts on how to fire up the engine for the first time. I went through all of the regular stuff and eventually gave it a crank. It sounded somewhat promising but would not run. Gave me a few sputters and the longest rough idle was maybe 6 seconds. We decided there may be a fuel problem so we used a little starting fluid to see if the motor would try and run on that (as we have with countless other motors including LS motors) to be sure there was a fuel issue. It did the same thing as before. After hours of research about crank and cam sensors and PCM issues, I decided to run a compression test. The first cylinder I checked (5) showed 240 PSI. The next (3) showed 160 PSI. A buddy mentioned from cranking and not running, some cylinder walls may be washed out with fuel, so I did not want to crank the motor over any more and run the rings on washed walls therefore I did not check the other cylinders. I pulled the intake checked the cam sensor and wiring, looked in the intake ports which looked brand new still, put new gaskets on the intake, bench tested the stock injectors and 4 of them were dripping not spraying, even after seafoam soaking. Cleaned all the fuel lines (after I had pulled the tank and found a corroded rubber line from the pump which I imagine sent some stuff through the lines and injectors) and put in different injectors. Squirted oil in the cylinders through the spark plug holes and put it all back together for another compression test.

Put the compression gauge on cylinder 1 (which had been 160 PSI) and it showed 0. I figured the gauge may be messing up so I put it on cylinder 3 (which had shown 240 PSI). It showed 240 PSI again. So i put it on cylinder 5 and it also showed 0. I tried 3 and 5 again and still 0, needle on gauge not moving at all. Both cylinders showing 0 noticeably did not create compression against the starter. Cylinder 3 was pushing air through the spark plug hole and 1 5 and 7 were not. On the other side cylinder 4 and 6 were pushing air and 2 and 8 were not. I pulled the valve covers and everything is moving nicely. On initial start up I had cranked the car with fuel and spark unplugged to build oil pressure until oil flowed through each pushrod and pumped up the lifters. I pulled the rockers off of cylinder 1 so the valves would be closed, and removed the push rod and cranked again, still no air movement through spark plug hole even with thumb blocking the entire hole.

I'm really sorry for the long post but I am curious if anybody has any Idea what may have happened here. Clearly I am going to have to pull the heads because something has happened, but I wanted to pick some brains about what may have caused this. I assume either the valves are bent or these select pistons have been damaged enough to have absolute zero compression. But all of these pistons damaged at once? And if the valves were bent, shouldn't I assume a timing issue would bend valves on all cylinders not just some? Any insight would definitely help as I have had a very confusing and frustrating few days.