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dsiegel360 dsiegel360 is offline
Doug Siegel
Join Date: Oct 2007
Location: Bloomington, IN
Posts: 314
Originally Posted by fredmeister View Post
Great thread guys.....
I am having similar issues with pinging last nite since I changed from a 0.8bar boost spring to a 1.0bar spring.
My car is a 79 930 with the dual port can, the boost retard is open to atmosphere. Vacuum side is connected as normal.
Checked timing and here is what I have which confuses me:
at idle of 1000rpm..... timing = (neg) 7 degrees BTDC VACUUM PORT CONNECTED
at idle of 1000rpm..... timing = (neg) 29 degrees BTDC VACUUM PORT DISCONNECTED
Honestly I was shocked because I thought that the 29 was aweful high at idle because as I rev to 4000rpm (NOT DONE AS YET, SO CANNOT REPORT RESULTS) I expect the mechanical advance to go even higher.
Now the safe limit from other posts I have read under full boost and high revs indicates 26-28 degrees max timing BTDC......I wonder what it will be when I run it up to 4000rpm with vacuum disconnected.
1) In short, how much more advance does the mechanical advance add by itself?
2) Are my mechanical advance weights frozen at idle to explain the above results so far?
When I told Brian Leask that I was ready to go to a 1 bar spring, he suggested purchasing a modified fuel head from IA. He said that I'd need the 20% extra fuel otherwise full boost enrichment would prove lean. I have the PLX afr gauge, thus I can tell you that at 1 bar WOT, I ain't lean. Along with the fuel head, I had to buy the rpm activated solenoid from Brian. Of course, the adjustable WUR is part of the equation too. I'm sure lots of people run 1 bar without the extra fuel, but I wonder what kind of readings they are getting, if any at all. I assume that with a 1 bar spring, an afr gauge is a must.
Old 04-10-2008, 08:19 PM
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