Maybe your real lean on your car adjustments? If it is burning real rich it has bad fuel odor too. Is your breather on the valve piped back into your air cleaner? unburned fumes smell.
Just thinking of other items.
If I recall, I moved the idle mixture until the engine stumbled and the backed off either a half or quarter turn (according to Chilton's).
But twice in the last two weeks, I have noticed a black chalky substance directly behind the right tailpipe on the concrete. It looked like soot. Over-rich?
