Which is the correct A/F ratio ?

[RICK LAKE]

Stephan427SC Steve There is a idea A/F ratio for making the most torque from a motor and making the most HP from a motor. Under full throttle you are looking for 12.7-13.2 for the max power range on most motors. At Cruise a 14.0- 14.3 is a safe ratio. You can run leaner if you want but may start to burn down the motor over time. The best thing would be to find a good dyno shop and let them setup the car. If the motor has forged pistons you can run a little leaner, if cast you are looking for trouble. Reading the spark plugs will help. Have you air balanced all 8 webers for flow? What camshaft are you running. Does it have a 113-115 LSA to stop reversion of the motor? You might want to setup a base line and record each change. start at idle and check the A/F ratio every 250 rpms and record. Do 1 change at a time and retest. Will take time. If you get lost go back to last step. Timing will also effect power the motor produces. Some motors like alot of timing, others like a little, this also depends on the gas and qualitity. Good luck on your learning curve. Rick

[olddog]

Afr at idle typically was a bit rich 14.2ish with a carb. However you need to understand that the cam matters. Large valve overlap causes unburned air fuel to be pulled into the exhaust. A wide band O2 will see this air and report a false lean afr. So the O2 is working correctly, but you have to understand the what is happening or it will lead you astray.


So the person who told you to set it too lean, either understands this and knows your engine, or doesn't know know didly. I'll let you figure out which.