vacum problems on advancing timing
 

73 450SL do not have any vacum to advance the timing? Car cranks and idles good but when you give it more gas it cuts out and back fires. Put in new plugs , new gas filter, cleaned gas tank. Just thinks it needs vacum to advane the timing . Help

you must have a crack in the main vacuum line , rear of manifold I think?

It sure could be a vacume problem. I have a '74 450 SL and when I bought it the vacume advance cell was frozen and did not move. The symptom was good idle but no acceleration at all. Once up to speed it ran ok. This car is powered by vacume . The transmission uses vacume, all the door locks, trunk lock, gas cap cover, cruise control, heater and air conditioner vents. Did I leave anything out??? I would suspect vacume leaks first and I would recommend buying a small hand held vacume pump to test all your lines. One last thing, there is a vacume storage canister used to keep the door locks working when the motor is shut off and some one way valves to keep the vacume from leaking out when the motor is off. Once you resolve your problems you are going to love driving your Mercedes..........Dan