Ignition/FIP Timing

[jcochran@cox.net]

Hi,
 When I received my recently restored 250SL I was not satisfied with the performance of the engine so I turned to this site (and others) for help and you guys/gals have been incredible in your level of knowledge/expertise and I really appreciate your help . The car is running 100% better now however to achieve satisfactory performance the ignition timing has to be advanced 20-30 degrees. The engine does not knock, accelerates well and has good driveability when advanced. Factory specs. are 8 degrees w/o vacuum so I am concerned as to why my car runs so well so far out of spec. Because the engine runs so smoothly I fell that mechanically the timing is correct which leads me to wonder if the FIP timing could be at the root of the problem. The F/A ratio is good, dwell angle is good, idling is good, etc. If I set the timing back to specs. the engine misses, has poor acceleration, etc. There is probably a simple explanation for this but I really would appreciate any advice or ideas that you can share.

Thanks,
Jim Cochran

[ja17]

Hello Jim,

Set the timing at 3,000 rpms. first 30 to 38 BTDC seems to be "the sweet spot"  and should be close to spec.  Idle timing is less critical. Many different mal-functions in the distributor can cause idle timing to be off. 

[ctaylor738]

Here is a very simple way to check the pump timing w/o removing the pump:

http://www.sl113.org/forums/index.php?topic=16056.0