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356-930 356-930 is offline
Acceleration Junkie
 
Join Date: Aug 2007
Location: Laguna Beach, CA
Posts: 263
Garage
Quote:
Originally Posted by beepbeep View Post
I dunno how your dizzy advance/retard is configured (there are plethora of combinations depending on which market car was sold for, Cali and Japan being the most complicated) but you could re-route retard to give you more advance prior to boost?

I did just that on my SAAB og900 daily driver...I connected retard line on plenum itself instead of pipe going off the throttle housing (which gives no vaccum on idle). That gave me much more poke off boost. I'm running on E85 though so knock is more or less impossible.
My stock 930 dizzy is a dumb 2-port device. Vacuum on both ports retards timing (because vacuum on the boost retard port has no effect). Positive pressure on both ports also retards timing (because positive pressure on the "vacuum advance" port has no effect). Confusing huh? In the case of a dizzy, dumb is a good thing.
I used to run the engine 22-deg BTDC, no vacuum advance (same effect as plumbing retard line on plenum) and still not enough timing to wake the engine up below boost. It liked 27-deg BTDC at idle but it wouldn’t really idle, misfired above 2000 rpm unless under load and EGT got too high.
To optimize these early 930’s performance, a crank fired ignition and computer controlled timing has my vote. And, if I get to vote twice, add EFI. (This said, IMO, an early 930 is a wonderful power plant including all it's limitations.)
Lastly, I apologize for being so far off the topic.
Old 06-22-2008, 11:39 AM
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