Thread: OZ Duster
View Single Post
  #24  
Old 08-25-2010, 07:17 AM
GregWeld's Avatar
GregWeld GregWeld is offline
Lateral-g Supporting Member
 
Join Date: Jul 2005
Location: Scottsdale, AriDzona
Posts: 20,741
Thanks: 504
Thanked 1,080 Times in 388 Posts
Default

Air fuel ratio is a relative game.... idle is one thing -- cruise part throttle low load is another - and Wide Open Throttle is another...

You're right 14.7:1 is perfect -- but maximum effort WOT requires mixtures around 12.8 or 12.5.... which is why I asked you - because you seemed to want to see 14.7 there and that would NOT be good.

Idle just needs to be what the motor wants -- which is what an idle adjustment screw is for -- you want this adjusted for "max" RPMs (without touching the throttle/idle adjustment) and vacuum. Some motors need a A/F ratio fatter to achieve that than others... so it just "is what it is".

Cruising - light throttle - light load - can even be leaner than 14.7 -- new fuel injected cars might even hit mid 15's. You can go to 14.7 and be "comfortable" with that.

WOT needs to be where the motor wants it (thus a dyno - to find what that is) but is typically mid to high 12's even in a modern EFI motor.

If the car runs well - doesn't buck - doesn't ping - idles fine -- then you're good to go.

TIMING will actually make a far larger difference in HP/TQ than a perfect fuel ratio.
Reply With Quote