On my '79 244 DL the idle recently became rough. I checked the distributor cap and rotor and it is charred on the inside at the base of the metal pegs. Also there was some charring in the sockets on top where the plugs connect. On the inside the charred part started to make a depression. It was just before the peg. So I am pretty sure the timing is off. I changed the cap and rotor already and I am changing the timing belt, altenator belts, and the a/c belt. They need it. And I was thinking what else should I replace while I am doing this? Also I was thinking that I should check the distributer its self. What should I look for?....Thanks in advance..Paul.

You didn't mention mileage nor how long since the last major service, so here's the really major service (100k) items you haven't yet done:

Things to replace:
Spark plugs, properly gapped. Flame trap. Filters (air, oil, fuel). Change the oil religiously, every 3 months or 5k miles. O2 sensor (get the generic Bosch part from a major autoparts store). Drain & replace coolant, power steering fluid (should be red like burgandy wine), brake fluid (should be crystal clear; replace by bleeding if not), washer fluid.

These are controversial but I've had good results from changing:
Manual transmission oil (and overdrive filter) or automatic transmission fluid. Consider changing the differential oil. All vacuum lines and connectors: amazing improvement!

Things to inspect:
Check all wires in engine compartment for insulation failures. Clean all electrical connectors to components, wiring bundles, and ground points. Suspension, especially rear springs and all bushings. Make sure the oil breather box is not clogged. Check all seals for leakage. Check valve clearance (on a warm engine, plan on a couple of hours and expect to swear a lot. I also replaced the rubber tips on the end of the valves: much less valve noise. Sounds like a different engine!) Clean all light bulb connections. Clean the fuse connectors. Inspect relay solder pads (inside the relay box) for cracks and failures: search the FAQ and archives.

General service:
Grease door hinges, lock strike plates, hood latch strike plate, electric window motors, hood hinges. Clean the sunroof tracks and actuator (if you're lucky enough to have a sunroof). Clean and oil the power antenna.

That will keep you busy for a while. I've done all these things at various times for my cars. All have been rewarding -- some astonishingly so. My '82 244 has over 325k miles. It has more pep and drives better now than it ever has during my 5 years of ownership.
--
-- Bruce / '82 244 (315k miles!), '86 745, '87 760Ti, '94 854

i am not entirely familiar with how the '79 engine is set up (b21?), but i would replace the front crankshaft seal since it is easy and right there, did mine with a $1.19 piece of PVC pipe end from ACE hardware (no endorsment) and it pressed right in. possible even do the water pump too, depending on how old it is.

just some thoughts!
Good luck!
Chuck