friend and i just finished a ls/vtec swap into a crx and we checked the compression in all the cylinders. the first through the third are all at 195 psi, but the fourth is showing 120 psi. the b18b block/head was fine before the head swap..... would the cause of this low compression reading be caused from a bad valve stem seal?

 

your valves should be closed which means that the valve/valve seat it self would have to be leaking, the it will all leak out via the manifold. i would be looking some where else ie valve backlash, dirt under the seat not allowing it to close, worn rings etc.do the old favorite of putting a teaspoon of oil down the sparkplug hole and redo comp test. if comp goes up it's something in the rings if not then look at your valves.