is it a really bad smell? if it isnt your every day oil burning smell then i would take off the oil filler cap and if the smell gets worse/originates from there, you more than likely have an oil pressure issue (not enough oil reaching the head) and your actually "burning" the cams. This happened to me once when i made a stupid mistake, put an n/a sump on as a quick fix, but was in a rush and forgot the pickup was longer, so crushed it and fried the head. Chunks of my cams where missing..