Okay so my free 91 EF 4 door is finally apart and it turns out that cylinder 3's exhaust valve has managed to somehow lose a piece of itself!

The valve cover is covered in gunk/sludge and the rocker arms are a dirty reddish color. Probably overheated/poor maintenance.

I noticed that the valves have an enormous amount of carbon build up. What the heck would cause this? Poor maintenance? bad gas? It literally looks like baked on crusties.....

Also since I have my Si head can I simply bolt on the Si head and reuse the D15 cam and the crappy DPFI manifold? I don't have an auto D16A ecu handy and I want to get the car going for as cheap as possible.

Suggestions would really help.

Thanks