Thread: Ignition Timing
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fredmeister fredmeister is offline
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Join Date: Oct 2002
Location: Baltimore, MD, USA
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Originally Posted by e170drvr View Post
Fred, Yes your post was clear on how you set up with the hoses. I'm guessing you have a 930/66 motor. If that is the case the ignition timing according to the factory workshop manual for 930/66 is 29 degrees +/- 1 degee BTDC vacuum hose disconnected. and then for checking again 930/66 2 degrees +/- 2 degrees BTDC at 900 +/- 50 rpm. What I was unclear on is say you measured 6 degrees retard with the hand pump you talked about. are you setting the timing at 35 degrees BTDC at 4000 rpm, with the knowledge that the boost pressure retard will pull it back to 29 degrees BTDC. I just think that might be a bit too much advance. But again the idle timing is supposed to be at 2 BTDC 900 RPM I think you said you are happy with that for off boost response. If you need any of this stuff from the workshop manual, I would be happy to send whatever you need.
What you described exactly. Those values are pretty close to what I remember now timing to.
I am not sure that 35 degree is too much at no boost conditions because I figure with the low cpmpression motor of 7 to 1 without boost pressure is probably ok. Dynamic compression is still lower than a normally aspirated 911SC wich I have heard run best power at around 35-36degrees advance. Once boost starts building then it retards back to be safe. So far I have been running this way for a year or so now and never detected knock. Though I am not sure I would be able to hear it anyway, and they say damage can be done without audible warning. I have removed plugs and never noticed burning or damage to them so I feel about 90% confident I am ok. The other 10% is what bothers me and I would like some more opinions from gurus off this site.
Appreciate the offer on manuals but I have the complete factory set already and have used it to check against what I could find among the 3 or 4 different factory curves for boost and dizzy advance.
You know my goal is to max hp against a non emission restricted car and without running on dyno and measuring everything to tune to the ragged edge (since I am just a working slob without major fundage) I just wanna get as close as I can myself out of my garage and not hurt my engine.
1979 930 Turbo....3.4L, 7.5to1 comp, SC cams, B&B intercooler, Snow Perf water/meth injection, Rarlyl8 headers, Garret GTX turbo, 36mm ported intakes, Innovate Auxbox/LM-1, custom Manually Adjustable wastegate housing (0.8-1.1bar),--running 0.7bar max
---"When you're racing it's life! Anything else either before or after, is just waiting"
Old 02-13-2009, 08:12 AM
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