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RarlyL8 RarlyL8 is offline
Crotchety Old Bastard
 
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Join Date: Jan 2000
Location: Huntsville, AL
Posts: 13,525
Garage
As you have seen the 930 dizzy does not have a vacuum advance. It also does not have a boost retard. For the 2 pot units one pot is a vacuum retard (at idle) and while the second pot is actually a vacuum advance, but the performance function does not allow advance due to the signal being positive pressure. What you end up with is vac retard at idle, vac/mechnical advance at cruise, and mechanical advance only on boost.
You can test all of this with a vac pump, an air compressor, vac/boost gage and a timing light while your engine is running from 1000rpm - 4000rpm.
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RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8
Old 04-06-2008, 05:55 PM
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