Air/fuel ratio?
 

I recently had my car dynoed. This shop had all the bells and whistles for their DynoJet including an exhaust gas analyzer. The car dynoed well for me (280@5700/293@4000).

The printout included the A/F ratio for the entire run. In the usable rpm range the A/F stayed between 12.7-13. The dyno operator thought that the 12.7 area was a little fat and recommended maybe slightly smaller jets and/or power valve number.

I thought the 12.7-13 was about ideal for a carbureted car. Any opinion, recommendation, or other thoughts are appreciated.

Rev

Re: Air/fuel ratio?
 

I'll usually shoot for 13.0 on the low end of things. Stochiometric for gasolines is 14.7:1 (hottest point). Too bad you couldn't have re-jetted while you were on the dyno to see the effects of one jet change on both A/F and HP/TQ. A single jet size is 7% change so IMO it probably would have leaned you into the 13.0-13.4 range and I'd bet would have been worth a little HP.

Re: Air/fuel ratio?
 

Actually, I did go from #70 to #68 on the primary jets a week after the dyno pulls. I tested it on the Gtech, but really couldn't see a difference. Might have even dropped a couple hp. The plugs are a very light tan now which is about how I like them to look.

Seems like atmosphereic conditions make a lot of difference on the Gtech hp/torque runs though, so repeatability is always a question. They actually would have let me tune on the dyno for a price.

Rev