Originally Posted By: chrisri
How to enforce it? Simply really. You have annual MOT/ vehicle inspection /registration were technician can detect any faults with vehicle, including emission devices.
Even simple visual inspection is sufficient- vehicles with working DPF will emit zero soot/ smoke even at throttle.
It's my understanding that California actually does a fairly stringent visual inspection in addition to using a tailpipe sniffer or other quantitative methods as part of emissions inspections-or at least on cars for which emissions testing apply(I think 1974 is the cut-off year).
There are threads on the MG forum that deal with passing CA smog checks, as some emissions parts are are no longer available. The smog pump is a big one, and there are folks who run it with a hollow body as they can't get a replacement for a seized one. One common trick is to lean the car out pretty dramatically for the test to get CO and VOCs down(and hopefully you have a functioning EGR valve, which is also tied into the AIR system, to help keep NOx down).
One of the other issues is that the catalytic converter must be within 3" of the manufacturer location. CA-compliant cats are expensive and not very good, so I know of more than one person who runs a straight pipe through their factory cat and then puts the "real" one under the car(the factory location is right under the carburetor, a bad place if the carb diaphragm tears and it decides to start puking gas out as sometimes happens).
Of course, even doing common modifications like adjusting the timing curve in the distributor are technically illegal. Once again, I'm going to refer specifically to MGs because that's what I know. In any case, the go-to guy for Lucas distributors told me that the late cars have about 20º of mechanical advance at the cam(40º at the crank) plus a 15º vacuum can. With the base timing at 15º, you get 55º total advance at low load, high speed cruising and 70º under high speed and heavy loads. Advancing the timing that much gives the gas more time to burn which should theoretically lower emissions, but it can lead to pinging and overall poor performance. My car has the '63-67 distributor curve which, among other things, gives 10º of mechanical at the cam(20º crank) and is set to 32º maximum mechanical advance(vacuum disconnected). This is a "sweet spot" for the engine. In any case, replicating the advance of an earlier engine would be tampering with emissions equipment, but I don't see the average inspector mapping the timing or even checking the maximum advance(the latter is easy enough to do with a dial back light).
One last thing-I remember someone talking about getting "chatty" with the inspector and the inspector suddenly clamming up and directing the guy inside to wait. The inspector took about 45 minutes on the car. Apparently it's not uncommon for CARB(California Air Resource Board) to send guys out with older cars that have a minor issue, then cite the inspectors for missing it. They often are "chatty" apparently, and the inspector gave the car extra scrutiny because there "had to be something wrong." The car passed perfectly, but there again apparently the guys doing this really DO take the visual inspection seriously.
