Holley Transition Circuit Tuning

crackedback said
When you say it goes lean, if you are using an AFR, don't sweat it so much. Going lean and pulling back is fine. Put a larger squirter on it and possibly change the pump cam to a more aggressive profile if the lean condition is problematic when mashing the throttle.

I've run my stuff at 15.5 cruise afr and higher. As long as the plugs are good and the engine isn't surging, tying up, overheating, etc. lean is mean...

Thanks! I hear ya. At slow cruise (barely off idle), AFRs were in the mid 16's and more importantly, the 340 wasn't liking it at all. It was not running well. On the power valve, it had a very slight lean bog when I leaned into it. Maybe that will go away once I sort out the idle circuit. But yeah, I've got plenty of pump cams and squirters to play with too. Right now, It's got a red cam and 31 squirter.

Mattax said
Some one hasn't said it yet??
The AFR number is just a number. Don't aim for AFR numbers. They are just a reference that can be helpful in seeing what a change is doing.
Yea sure the FSM in the very end of the 60s is concerned with AFR at idle because of the need to reduce CO - hence the lean idle mixes targetting 13.9 or 14.1 or whatever it says.

Thats a huge amount of initial timing unless the engine is something like very high overlap and somewhat lower compression. Over 240 at .050? With a cam like that 750-800 in gear is pretty good in my opinion, and with 12"Hg thats about where my engine is with roughly 230 degrees at .050. Except its timing is around 17 to 18*
What is the idle rpm in Park or N?

IFR of .027 and .070 IAB isn't crazy
Going from .027 to .030 should be a noticible change.

I'm definitely not aiming for an AFR in particular. I'm using those numbers just to see if the changes made are doing anything and where, and to confirm what I'm hearing,seeing, and feeling in the way it's running.

The engine definitely wants that much initial advance. Compression ratio is 9.6:1 and cam is 231@.050, .561" on a 108. RPM in P or N is maybe 25-50 higher. There's barely any rpm drop in gear. It surprised me too when I played with the timing, but anything lower than 20* and it was not as happy.

Thanks again for your help. I appreciate it.