Duke,
I won't get into the required octane bit right now, because I don't have time to dig up, scan, and post the documentation. I wouldlike to discuss changing timing on the M103. I don't understand what you are talking about with vacuum advance.
The distributer is bolted to the front of the cam with no advance capability. Your thoughts on replacing the resistor that maps the EZL are interesting. I'll have to experiment with that. I got rid of my 90 300SEL, which was a bear to pass smog, but, I still have an 88 300SEL. The 88 has a problm just getting by on the 15mph and 25mph HC readings and my O2 is .5 %. I'm trying to figure out why some M103s fly through the test and others get bogged down in the HC category. NOX has never been a problem. About plugging the vacuum line to the EZL, you might get away with that on most year Federal cars, because the only thing that will trigger the MIL in Federal cars is the oxygen sensor. Not so with California cars, because you will trigger a code 16 and set the MIL. TRhis is also applicable to the M104 engines.
Warren,
If you are hearing sounds from places like the fan pulley, the bearings are probably about to grenade on you. As too your stumble, Folks in other threads have been very successful in curing cold idle problems by tweaking the screw on the back of the EHA. I haven't had a chance to experiment yet.
You have a luxurious $3000 car that still gets attention, costs you several hundred dollars, and you call it a money pit. Buy something like a new 04 Dodge Neon if you want to own a money pit. Yes, you have to keep putting money into that old car, but save your receipts for 5 years. Acturial tables show that the $13,000 Neon will cost you over $30,000 in the first 5 years of ownership. Many years ago a friend got a job that required a 60 mile or so commute for about a year. He started a car pool with 3 other guys. They all went out and bought new little economical rice burners. My friend bought a 65 Pontiac Bonneville for $500. They always wanted to use his car, because of the room and A/c, but they all shared as per the agreement. Afret the year was up, they had car payments, registration, maintenance, and insurance on cars they didn/t need. My friend sold his Pontiac to a low rider for $500. He had cheap registration, basic insurance, and a few hundred extra dollars in fuel costs.
Peter