Does popping mean lean or rich?
The popping is a result of the air/fuel mixture becoming very lean when the throttle is closed and the engine is rotating well above idle speed. It is also necessary that the exhaust system have rather open mufflers.
Why does a lean engine pop on deceleration?
The exhaust gas temperature of a lean engine is substantially higher than one that is running on the rich side ( an EGT probe will show this). Therefore, the high EGT serves to heat the pipe more and the gases themselves become a much better source of re-ignition.
Can a lean condition be indicated by popping?
Most times a lean condition WILL be indicated by popping, but not always. TW This is exactly correct! If you think about the mechanics of what is going on upon decel, it makes perfect sense:
What causes a CARB to pop on deceleration?
You start out with an engine that is turning high RPM with a carb that is open, flowing freely. Next, you close that slide. This has the effect of creating a tremendous vaccuum in the intake manifold (CHOKE!). This vaccuum does curious things: 1. It pulls air and fuel from wherever it can–including the idle and low speed jetting in the carb.
What should I do about popping on deceleration?
Turn the screw till fastest idle. Turn the screw in from there until it stumbles and remember where that happened (think of it like a clock). Now turn the screw back where you had it and turn it out till it stumbles and remember where that happened. Now turn the screw half way between the two points.
The exhaust gas temperature of a lean engine is substantially higher than one that is running on the rich side ( an EGT probe will show this). Therefore, the high EGT serves to heat the pipe more and the gases themselves become a much better source of re-ignition.
You start out with an engine that is turning high RPM with a carb that is open, flowing freely. Next, you close that slide. This has the effect of creating a tremendous vaccuum in the intake manifold (CHOKE!). This vaccuum does curious things: 1. It pulls air and fuel from wherever it can–including the idle and low speed jetting in the carb.
Turn the screw till fastest idle. Turn the screw in from there until it stumbles and remember where that happened (think of it like a clock). Now turn the screw back where you had it and turn it out till it stumbles and remember where that happened. Now turn the screw half way between the two points.
What happens when you tune the acceleration enrichment?
Before you start tuning the acceleration enrichment, make sure your VE tables are dialed in. Adding a correctly tuned amount of acceleration enrichment to an incorrectly tuned fuel table is still going to result in an incorrect amount of fuel.