I have a question about setting the timing on my 1.8 ignition with the L-jetronic. The Haynes manual says to disconnect all vacuum hoses when setting the correct timing. Maybe a dumb question but I don't want to mess this up, I assume they mean just the two vacuum hoses on the distributor, right?

Correct. Disconnect and plug both vacuum lines on the distributor.

Okay, thanks!

At the prescribed elevated rpm, too. I get it as close as possible, then tweak it a bit to what the engine is telling me it likes best (usually just a tad more advance), then reset idle speed screw accordingly.

The L-jetronic needs to be adjusted at 900 rpm, right? I bought a fancy timing light that will tell me the dwell angle and rpm too so I should be able to set it just perfect.

the truth is your distributor (if its original) is an emissions device.
the vacuum can that is.

the retard side of the can uses engine vacuum at idle to pull back the distributor and further retard the timing. lowers NOX and hydrocarbons.

the advance side if it is an EC-B engine and has the hose connected up to the throttle body is a fuel economy device at cruise.

so what you are doing by disconnecting the hoses at the distributor and plugging them is neutralizing the effects and going for a "pure" tune of idle at 7.5 BTDC.

you get it to idle nice and steady. usually around 950 +/-.

then reconnect the hoses. the idle will change. often less and less steady.
then do a final tweak of the idle screw on the throttle body.

@StarBear knows the trick because he has done it a million times for 50 years!!!
he sets a bit high with the hoses off in anticipation.

make sure your valves have been adjusted first before you do all this.
i guess you know that.

the timing marks on the fan can be a bit obscured by time.
put a dap of paint or texta on the 7.5 BTDC mark once you have located it.