Timing Belt 1986 Caddy

It doesn't even have a timing belt and if it did, changing the valve timing certainly wouldn't help your problem.

I have no idea if that will solve your emissions problems and neither do they. The car would have to be tested and different things tried while it's hooked to the emissions machine. There are a number of different ways it can fail. There are 4 different gases that are tested.

No, it doesn't. There is no test for timing. It only measures the amounts of 4 different gases out of the exhaust.

You failed for 3 different things that I can see. Yes, your ignition timing is set too far advanced but you also have too much HC, and a check engine light on. You need some serious diagnostics.

Your check engine light is on. You WILL NOT pass until the reason for that light is repaired. Changing the ignition timing may also make the other readings much worse.
Unless you have a timing light and a way to read the exhaust emissions simultaneously, you'll likely make your problem much worse.

Here are the timing instructions anyway

SET IGNITION TIMING

The ignition timing marks are located on the engine front cover. A slot on the balancer indicates engine top dead center.

1. With engine RUNNING at operating temperature, choke fully open and air conditioning off, ground the diagnostic terminal of the ALDL terminal.
2. With the use of a timing light or meter, set timing at specified RPM, by loosening the distributor clamp bolt and rotating the distributor until specified timing is obtained.
3. Tighten the distributor clamp bolt and recheck timing to make sure the distributor was not moved during tightening.
4. With the engine still running, unground the diagnostic terminal.
5. Make carburetor adjustments as required.

If u change the oil and go get it checked your hc will be lower