Hello to you all, this is my first post. I was going to do a search on this subject but couldn't find a way to do so...so hear it goes. I have a '90 GT with a mildly modified 306 with Edelbrock Performer RPM alum. heads (#6025 with 2.02/1.60 valves)) with a Performer RPM 2 manifold, B303 cam & 1.72 roller rockers (stud mounted). I recently removed the intake manifold to replace the lower intake's gasket because there was a slight leak at the front/center of the manifold. While the intake was off I pulled the valve covers to clean & replace gaskets too. This is when I found a valve spring shim that had broken in two!! Luckily I was able to find both pieces & they matched up perfectly so I know there isn't any other pieces floating around in my motor...whew!! I'm still going to change the oil & possibly pull the pan just to make 100% sure though. I'm going to have to pull the rocker arms to find which valve spring has the missing shim & replace it, so I figured this was a good time to readjust my valves. I did this once before myself, but that was about 12 years ago & I've lost the documentation that explained exactly how to properly adjust valves (w/ hydraulic lifters) with the heads still on the engine. I watched a couple how to videos online but didn't see any that went about it the way I was told to adjust them all those years ago...which did work by the way. I remember starting with the engine at TDC adjusting intake & exhaust valves on certain cylinders (sorry can't remember which), turning the engine over 180 degrees & adjusting intake/exhaust on a couple other specific cylinders & lastly, turning the motor over another 90 degrees and adjusting the valves remaining. Does that sound familiar to anyone? The how to videos I pulled up recently started at TDC adjusted #1 cylinder, then turned motor 90 degrees & adjusted the next cylinder in the firing order, then another 90 degrees & onto the next cylinder in the firing order sequence, etc. However, I don't remember turning the motor over that many times. What exactly is the proper way? Any help would be greatly appreciated! Sorry for the lengthy post!