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1974 450SL, Dark_Blue/Parchment
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The 5 degree ATDC is an attempt to reduce emissions during idle. It is not neccessary to set the timing that way. In fact it is turned off whenever a/c is on or if coolant is over 100C.
Your car will run better if you set timing at 5 to 8 BTDC with the vacuum line to distributor disconnected and plugged. Reconnect vac after setting. At idle, you will now be at tdc - 5 BTDC Timing should then advance to about 27 BTDC when you rev to 3000rpm. If it doesn't, then there is a problem with centrifugal advance (internal weights)
Would this be advisable for a 74 as well?
 

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'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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I assume it would be exactly the same for a 74 as it had the same original specs as the 73
Right! Set at 5-8 BTDC (with vacuum line disconnected and plugged) and then check to see that you get advance to somewhere around 27BTDC when you rev briefly to 3000rpm.
 
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Registered
1974 450SL, Dark_Blue/Parchment
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263 Posts
I assume it would be exactly the same for a 74 as it had the same original specs as the 73

Right! Set at 5-8 BTDC and then check to see that you get advance to somewhere around 27BTDC when you rev briefly to 3000rpm.
Thanks Gentlemen, think I’ll go out and try it right now! (y)
 
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