Quote:
Originally Posted by Tom Vaught
The video explains basic air/fuel values for different mixtures.
It said nothing about what each carb circuit did, when it did it, how it did it, and what the effect would be on the total air/fuel curve that the engine sees in the different modes of operation.
The video DOES tell you how to understand the air/fuel numbers that are being displayed on your AEM X-series Universal Exhaust Gas Oxygen (UGEO) gauge.
In simple terms: it is a cold day outside, the front door is wide open, you go into the bathroom and close the door. Yep it might be warmer in the bathroom vs being in front of the open front door (but you really did not fix the problem. You avoided the problem or did not understand the problem where the fix was to close the open front door.
That applies to your adjusting the idle mixture screws trying to tune the midrange circuits on the carburetor.
Idle circuits are for IDLE and Off-idle fueling requirements when the throttle blades are barely open. Not when you are cruising down the road at higher throttle blade angles.
Hope that helps.
Again, My recommendation, send the carb to Dick Bonesky and you will be a lot happier.
Then you can read the air/fuel ratio numbers when the carb is tuned correctly for your engine.
Tom Vaught
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Thanks for taking the time to respond and for the explanation. I didn’t say it up front, but my main goal is to achieve the best overall performance from my 389 that I can without modifying anything, i.e. not disassembling things and sending them off. Besides looking at the carbs and adjustments I can do to them, I’m also exploring adjustments of ignition timing that I can make that might improve performance. I’m not looking for monumental gains here, my thoughts in all this are, if I can improve performance in any way,
no matter how slight, by making adjustments only, then it’s a win. The other prominent goal is that I learn things along the way. I will also mention that my center carb was recently restored by Mike Wasson at Pontiac Tri-Power.