Afr Readings On Mi16

[craig_007 1]

I just installed a wideband AEM afr gauge on my car.

 

The car is runing on bike carbs and I'm just curious as to what mains people have run in the past.

 

The carbs were initially set up by bogg bros but not on there rollers.Anyway my first flat out run in 4th gear showed a AFR reading of 11.7,I knew this was on the rich side so I have rejetted.

 

The jets that were fitted originally were 160s (1.6mm)

 

I've dropped the main jet down to a 140(although this is a Dyno jet 140 so is slighty larger than 1.4mm)

 

My afr reading is now 13.7 on full load in 4th,Whats your thoughts on this ?

 

Also what is the easiest way of setting up part throttle,Is it a case of selecting a gear(say 3rd) hold the revs at around 3k and noting the reading ?

 

Must say though,Car seems to go a hell of alot better with the smaller main jets,Must having been over fuelling and causing a loss of performance !

[RossD 43]

It will vary from engine to engine, but usually low 13's and maybe down as far as high 12's should be ok for full throttle AFR. My TU 8v engine runs about 13.1 or so at full throttle. The only real way to tell is to get it on a dyno.

Edited May 17, 2010 by RossD

[petert 558]

13.7 is a bit too lean for full load. Try and richen to between 12.7:1 to 13:1, all the way from 2000 to redline at full throttle.

 

I'm not sure how you'll then lean them out for part throttle, but you should be aiming for high 13's to low 14's. Then 14.7 at cruise.