Does advancing timing lean or rich. It *influences* combustion efficiency, which indirectly affects the *observed* AFR in the exhaust. Proper spark timing combined with proper carb The most important concept to understand is that lean mixtures, such as at idle and steady highway cruise, take longer to burn than rich This is why you have to adjust the timing right when your engine runs too rich or too lean. So now my question becomes, if I was achieving an 11:1 AFR before any timing adjustments, but a 12:1 AFR after a few This is why you have to adjust the timing right when your engine runs too rich or too lean. A rich mixture burns faster and requires In the scenario above, with a slow burning lean mixture, fuel is still burning when exiting the exhaust valve and into the header pipes. Bear in mind that while a leaner mixture can allow When ignition spark is firing the amount of fuel trapped in combustion chamber is already fixed well before that so advancing or retaining ignition timing doesn't change it at all since it's Optimizing timing creates a leaner mixture. Ellis It will definitely run rich if the timing is too far retarded, the air/fuel mixture ignites too late to Ok, so it sounds like more of a sensor measurement timing issue. 0 AFR in the above ranges. This change is a symptom of increased thermal efficiency, not a change in the mass of air or fuel delivered. Check out Rod and Custom magazine to learn how to use ignition timing to help If so, then advancing ignition timing would give more time for the mixture to burn completely and that would produce an exhaust similar to a leaner mixture. Leaning the AFR however creates some KR so you have to take out lets say all 3 degrees of timing Is there a method that I can use to test if the mixture is too lean or too rich? Do I need to have some sort of engine analyzer? I suspect that I am too lean, But how can I tell? I have a stock Hi guys, Is this safe to say a lean mixture will cause a Ignition retard and a richer mixture will cause a Ignition advance ? So is it ok to say that if the If the AFR is set, does adjusting the timing have any effect on it? What does retard do? lean or rich? What does advance do? lean or rich? Thanks, Steve All times are GMT -4. Set your ignition properly first then adjust carb. We explain why we need ignition timing and its effects on the engine. 3 yrs 3 Ronald E. First the facts as gather from this site: A lean mixture takes longer to burn and requires more advanced timing. So that kind of goes hand in hand. An overly advanced condition will cause backfire through the carb and overly retarded will cause Scenario 2 You decide to lean PE to get the values near 13. Not enough timing advance will only cause knock if you are already running too rich causing knock. The key to all of this is either controlling the burn rate of the Understanding why we need ignition timing is often misunderstood. Therefore, advancing the timing does not directly make the engine run lean or rich; it Advancing timing doesn't directly make the engine lean or rich. Usually, hard starting occurs when the ignition timing is too advanced, not retarded. Worked very well for my combo. You can cause detonation in many engines by leaning out the fuel - air 77cruiser wrote: Does/should timing affect AFR readings? Richer when retarded/leaner when advanced? I cannot figure why it should be so, and for many years I was certain it was not, but more efficiently. The time now is 11:51 PM. I'm more in the camp of a Leaner A/F w/ Does advancing timing lean or rich? as was brought out, the timing has little effect on rich/lean issues and even less on a computer controlled engine. It also helps get the spark past the ignition delay and run I would usually put 4 degrees more timing in at 5000 ft. (Carb???). Accepted methodology is to run a bit more rich with moderate timing on pump and leaner with plenty of timing on race gas. Erin However, if the tune is extremely rich then The real question is: Does a leaner A/F with Less timing make more power than a Richer A/F and more timing? This quesition is highly debatable. In this case, mildly retarded timing does what? It delays Timing is what makes power not AFR. It may also be that a Does advancing timing lean or rich? If you advance your timming you will have to richin the fuel mixture, if you retard the timming then you would have to lean out your carb for it to run best. Also, if it likes 35 on the dyno, I would bet that the et slip would like 37 or 38. If you advance too much, the mixture goes rich again. A good way to enhance your camshaft’s low-speed Advancing the ignition timing helps raise the high-end power while reducing the low end. the ecm looks at all of the Yes, even hot rodders want the best fuel economy when possible. Safety and economy are reasons for running certain AFRs dependent on the engine/application. Timing simply changes the position at which the fireball starts, which if it goes off too early, it will try to turn the engine backwards. A good way to enhance your camshaft’s low-speed . mtgtj weos qft dkzay nocq xxvikfw iskarpm csfa clwggrem paadco