befu

iTrader: (2)

Hello. Basically running a stock L31 truck long block with a marine cam, dual plane aluminum intake and quadrajet carbs. Wondering what a/f ratios I should be looking at on my innovate gauge? Idling, coming up on plane, cruise and WOT?

Lots of info on here for blown or big block or aluminum heads, but this is a pretty stock carbed small block. Is 12.5 +/- .5 still valid on a motor like this? I have only checked on motor at a idle right now, but it was idling around 15 until I blipped the throttle and It dropped down some. I have to send this national carb back again as the accelerator pump does not spray a steady stream, kinda spurts and spits. National carbs, different nightmare all together there and a story for a different thread.

Trash

An AFR of 15 at idle is a little too lean for my taste. Not that you are necessarily hurting anything, but it has been my experience that no-load idle the motor prefers AFRs 14.0 or richer. For idle I would target 13.5-14.0. For most other operating bands I target 12.8-13.2 and will target 12.5 or richer in the upper load/rpm spectrum. Heavy acceleration regions I'd target 12.5 or richer. This has worked from my experience. I'm sure others will chime in.

If you simply targeted 12.5+/- .5 as you stated I believe you would safely operate the motor. Ultimately performance data (rpm, mph etc) will tell you what the engine likes best in your application.

Hope that helps.