For those of you that have been following my story of trying to get the 73 450sl timed to factory spec. It has now been achived.
Vacuum,vacuum , vacuum,
Putting all new vac lines on the car I still could not get 5*atdc. I checked vac at manifold 13#s, check vac at throttle body 8#s. Pulled vac line of HVAC cross-over valve, WOW idle went way up. Check vac again, now 19#s at manifold and 14#s at throttle body. I still could not get the vac retard on dist.. to work. I found that the vac line was too small. so I installed smaller line and wa la, the vac retard works. Adjusted timing to 5*atdc. Runs great,no miss and just purrs.

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Stable:
1973 450sl
1978 red diamond ice vette
1975 steel blue convertable vette
2002 steel blue dakota quad.