I am changing the cam in a 95 302 and when I pulled the valve covers I noticed that the left head has dark oil stains and the right one has light stains.Does anyone know why this happened. I'm thinking the left head was running hotter.The engine has 168,000 miles on it and has only used synthetic oil.

 

Has the right head ever been changed to your knowledge. The left head looks more like what I'd expect for a motor with 168k miles on it while the right head looks newer.
What does the bottom of the lower intake look like, does it more closely resemble the left or right head?

 

I've had the truck since it was new,this is the first time the engine has been opened up. BTW how did you add a pic of your truck in the top left corner of your post.

 

Strange. The PCV valve is in the passenger valve cover so it's possible you are getting some burnt oil residue back flowing into it if... the PCV valve is bad.

As for the pic go to your profile(user CP) and add an avatar pic. Note the pic has to e scaled down first.

 

Interesting...

I think Conanski is onto something. Probably has SOMETHING to do with the PCV and the way air is being evacuated. That right head is super clean for sure!