What happened to gasoline in the mid 1970s?
Another fallacy. There is no such thing as "unburned hydrocarbons". Hydrocarbons are a byproduct of BURNING fuel. Spent, burned fuel. Hydrocarbons cannot be emitted without fuel being burned. So the correct term would be "unburned fuel".
This is where my opinion differs greatly from that of the "exhaust police". I recently commented about this in another thread.
The way "fuel sniffers" have been programmed since the beginning is, they check for hydrocarbon emissions. If hydrocarbon emissions are more than "whatever" amount is allotted for a given car, or year, or "however" they regulate it, the vehicle fails.
I think this premise is incorrect. It's my belief the MORE hydrocarbons emitted, the more EFFICIENT an engine can be. Take hot rodders, for instance. Most hot rodders keep their mills tuned to the Nth degree. That means advanced timing, correct heat range plugs in good condition, perfect tuneup and so on.
I've always thought the sniffer should check for UNBURNED FUEL. In this way, it would be checking for total efficiency. To me, it makes more sense to use more of the available energy in the fuel. The way it is now, it set up so that the least amount of energy used from fuel nets you the "cleanest" results.
So which way is "more clean" ultimately? ........AND is it REALLY a big enough difference to give a damn about?
