Pagoda SL Group

W113 Pagoda SL Group => Electrical and Instruments => Topic started by: mulrik on May 01, 2006, 14:24:21

Title: Ignition timing
Post by: mulrik on May 01, 2006, 14:24:21

I had my distributor calibrated a couple of years ago and the car has been running great with the factory spec ignition timing. However, I'm curios if anything can be gained (horsepower, fuel economy, torque) by advancing the timing at 3000 until it starts pinging and then back off 3-4 degrees to be on the save side. Note, my distributor is the 051 with ignition retard.
Thanks
Ulrik

'67 250 SL Papyrus White 113043-10-000023

Title: Re: Ignition timing
Post by: Benz Dr. on May 01, 2006, 19:19:50

These engines respond well to all the timing advance you can throw at them. Often though, damage can start well out of the hearing range of most people. 3 - 4 degrees lower than pinging you can hear is probably safe but that depends on how hard you drive or how fast you drive long with what octaine you run.
 Every engine has a sweet spot where all these things come together to produce maximum HP. A dyno test would tell you exactly where to set igintion and oter critical settings.

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org
  1 877 661 6061

Title: Re: Ignition timing
Post by: bjudd on May 02, 2006, 17:07:48

what is a dyno test?  cost?

thanks

bjudd
1969 280 SL 5 sp

Title: Re: Ignition timing
Post by: TheEngineer on May 02, 2006, 19:23:13

A dyno test is where you lash the car unto rollers that are connected to a Dynamometer. It measures RPM and torque at the rear wheels. You are actually driving the car "in place". Usually a computer gives you a printout and a read-out on a screen showing torque, HP and speed, sometimes fuel mixture. You can load the engine that way and adjust timing to suit. There are also places that advertise having a dyno, but it is only a drum your tires accelerate as you step on the pedal and it shuts off when you reach redline. It also gives HP but does not provide a steady state loading. It is less desirable for making adjustments, although it serves for comparison. Cost varies, I have seen it for free to $145 per run. I have played with timing. The start of pinging depends on the octane of fuel. I use regular and my timing is set to the book, i.e. 30º at 3000 and about 3º after TDC at idle. Engine runs really very sweet that way. Dyno indicated 156 HP. Keep in mind this never was a hot rod, but a touring car.

'69 280SL,Signal Red,113044-12-007537,tired engineer, West-Seattle,WA (http://www.sl113.org/forums/uploaded/theengineer/20051219121123_Drehstern.gif)