I'm running Holley EFI, although I don't see that it matters really. Used a base tune and have been making the necessary changes over the past few months. Ilde quality sounds and feels great, but I feel it's a little rich. Just by smell. Old tune/engine never stunk up the garage with the door open. ANYHOW....to my question. Idle AFR is about 13.5. How much change is a good starting point? 13.7? 14? 14.7? Don't wanna go nuts and lean it out, but also don't wanna make tiny changes that won't actually affect anything.

I've read a lot and people seem to idle all over the place, but typically conversations seem to start with an AFR at idle around stoick/14.7

 

I would lean it out some, try 14.1 as a starting point. For a good idle need to run a little richer then stoich.

RBob.

 

Stoich on most pump gas with 10% ethanol is closer to 14.2 or so. I usually shoot for that

 

Cool, thanks. I'll give it a shot.

 

AFR value at idle is not trustworthy so just give the engine what it wants. The number will be what it will be.. The fuel smell can be helped by paying attention to injection end angle.

 

OK cool...I'll look at that. I'm learning. I've seen papers on "end angle" but honestly haven't dug too deep into it.

 

I use spark plugs and vacuum readings for idle as well. Overlap on cam can skew o2 readings. So plugs confirm whats goin on

 

I guess I should mention that if it is still batch fire then you have no control of injector end angle. Don't want to cause you to waste your time.

 

LOL, I'm glad you said that! I'm actually running "Paired" so I'm firing 2 at a time. Not true batch fire, but basically, yeah. I was thinking about what I know of end angle, and couldn't figure out how that was possible with multiple injectors firing like that. Never occurred to me that you could NOT in fact modify end angle. I just assumed I was missing something, being a tuning noob.