Timing guidance pulley marks

[Capt Bob]

I installed a new Perma-Tune 911SC903 ignition module and new SC010 coil in my 1982 930 and need to adjust the timing as I have some hesitation and misfiring around 3,200 RPM and above.

Right now with the timing light my engine is set at Z1 to the slot on the fan housing, vacuum line hooked up, engine at 180 degrees and idling smoothly at 900 rpm.

I have read some of the postings and am not sure exactly where to lock down the timing on this engine. Should I adjust to 5 degrees advance?

Any recommendations would be much appreciated.

[stevie 77 930]

Typically, timing should be checked @4000- 4500 rpm (vacuum lines disconnected) with a range of 26-29 degrees of advance depending upon other tuning factors.

930 Ignition Timing

Ignition Timing

[Capt Bob]

Thanks for the info. I will check at idle and 4,000 RPM vacuum disconnected this weekend.

The current set up is 5 degrees after top dead center at 900 RPM engine up to temp aprox 190 deg vacuum hose connected. Just went for a test drive and the car ran perfectly 1.2 bar boost.

[dap930]

Capt,

The stock ignition advance may be a little too much advance for 1.2bar boost. It will probably be OK when it is cool outside, but during hot summer weather it could cause some issues. Some people are using a programmable MSD unit where they can dial in retard as boost levels increase. 20* - 22* is probably the most advance to use, but other factors such as intercooler efficiency and AFR at those boost levels have an effect. I an running 17* @ 1.2bar & 11.5AFR, but I have a twin plug setup and EFI. With twin plug you can run less advance because you get two flame fronts which gets combustion started quicker.

[Rawknees'Turbo]

Originally Posted by Capt Bob

Thanks for the info. I will check at idle and 4,000 RPM vacuum disconnected this weekend.

The current set up is 5 degrees after top dead center at 900 RPM engine up to temp aprox 190 deg vacuum hose connected. Just went for a test drive and the car ran perfectly 1.2 bar boost.

If that is so, then you have negative advance currently (5 degrees ignition retard) - good for quick warm-up as exhaust temps will be very high that way, but not good for warm performance.

[Capt Bob]

Thanks and yes it was cool the other night when I went out for a test drive, maybe around 45 degrees out. I do not want to cause any pre-combustion/heat damage and want to get the car tuned properly for all seasons.

My 930 is set up with a K28-11RS turbo with a Kokeln IC. I'm not sure what my air fuel ratio is at this point but will have to find a place in Virginia Beach to check it.