Opinions wanted ( analysis of the effects of spark advance va riation on vacuum)

[James Northrup]

during my trials and tribulations with a leaky weber carb during my youth i came across a race-performance tuning manual that had an interesting tidbit.. (interesting to me, though I was uninterested in economy)
basically it stated you will do well to run your idle jets as lean as mechanically possible and still keep an idle.  (less idle fuel is somehow less cost, whatever the fraction)
...since the engine is under no load at an idle state there isn't a significant issue with heat.  (not an economy consideration, unless you count the lack of damage as economically acceptable)
...the engine will warm up faster, however, as there is in fact more heat being generated  (extremely relevant to fuel economy)
...that this ploy would produce a pleasing snap crackle & pop sound at idle (no comment)

...and the lean/warm/starving idle is conducive to a crispy throttle response with the addition of richer mixture from the pumps and jets. (relevant to mild & wild driving alike, i was heartily interested in this tidbit)
im not even sure what open and closed loop are, however, so your answer is unclear to me, even if its perfectly succinct and interesting :-)
  cmillard at crutchfield.com wrote: No sir, I'm done open loop idle before (PowerEnrichment enabled via TPS %) to control the fueling.  I'm attempting to optimize spark - which by the only definition I feel I can monitor ( no EGT, no EGOR, no cylinder pressure sensor) it the vacuum level (-MAP)I'm trying to stay closed loop idle, just for a change. Please let me know if I'm unclear- Thanks,-Christian-----Original Message-----
From: James Northrup [mailto:james_northrup at yahoo.com] 
Sent: Friday, September 21, 2001 10:59 AM
To: gmecm at diy-efi.org
Subject: RE: Opinions wanted ( analysis of the effects of spark advance variation on vacuum)

are you also attempting to lean?    


---------------------------------
Do You Yahoo!?
Get email alerts & NEW webcam video instant messaging with Yahoo! Messenger.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.diy-efi.org/pipermail/gmecm/attachments/20010921/5d0f7c9b/attachment.html>