Speed of knocking noise - the cam timing gear is TWICE the size of the crankshaft gear, because of this all valvetrain noise will repeat TWICE as often as bottom-end noise. So rule here is, if you hear a slow, rhythmic 'crisp' pounding then it's being generated from the bottom-end of the motor; OTOH if the sound is repeating quickly, it's most likely upper-engine valvetrain related (lifters or rocker arms). Mathematically, if the motor is idling at 650-rpm (stock) then a bottom-end bearing knock will repeat about every 1/10th of a second; valvetrain noise will 'clack' twice as fast, or about every 1/20th of a second.
You have some very useful information here, and I agree with what you're trying to do. I disagree with some of your basis, however.
You are correct that the cam gear is TWICE the size of the crank gear, but that also means the camshaft revolves Half the speed of the crank.
Mathematically, this is a 4-stroke engine which means the intake valve for a given cylinder only opens every other crank revolution, but you don't have to take MY word for it.
Diagnosing Engine Sounds.
in General SS
Posted
You have some very useful information here, and I agree with what you're trying to do. I disagree with some of your basis, however.
You are correct that the cam gear is TWICE the size of the crank gear, but that also means the camshaft revolves Half the speed of the crank.
Mathematically, this is a 4-stroke engine which means the intake valve for a given cylinder only opens every other crank revolution, but you don't have to take MY word for it.
http://en.wikipedia.org/wiki/Four_stroke_engine<br class="Apple-interchange-newline">