I had a valve spring break on my 454 and took it to a machine shop and had it repaired. During the process, I went ahead and changed the head gaskets on both sides. Now after hitching everything back up, I cannot get the car to start. When I do a compression check, it shows no compression. The gaskets are on there good and tight. The only other thing I could think of was the valve lash being adjusted improperly. I am getting fuel and fire but no compression.