I'm getting exhaust coming from all the bottom valve cover bolt holes on both sides of the engine. If the bolts are in the holes it doesn't leak exhaust, but I forgot one while changing covers and found the problem. I don't think its crankcase pressure either. With the bolt out it sounds just like an exhuast leak. tap tap tap. The heads are TF High Port heads and have never had a problem with them in the past. Car still runs fine and has power. Whats the diagnosis?

 

Sounds like the hole is drilled through to the exhaust port. Not a big deal, just leave a bolt in there