since lately you are talking a lot about the subject

Anyway, you have made it much clearer, and the PMS is not essential but you lose the times, anyway if you can clarify it to me, I would appreciate it, thank you.

Brief explanation of acronyms:

PMS = upper dead point of the piston, is the point where the crankshaft wrist has pushed the rod up and the piston has been stopped for a moment just before starting to go down.

PMI = lower dead point of the piston, it is the point where the piston has dropped to the end of his career (motor or does not give the same) staying stopped for a moment just before the crankshaft wrist and the connecting rod are pushing him up.

4 -stroke theoretical cycle:

We begin in admission, with the two closed valves (theoretically) and the piston in PMS. The intake valve opens and the piston descends causing a vacuum in the cylinder that aspires the air (diesel cycle) or the flammable mixture of air and fuel (Otto cycle).

Once the piston has reached PMI, the intake valve closes (theoretically) and the piston begins to climb with the two closed valves making the compression race.

At the end of the compression career, the piston is in PMS for the second time in its work cycle. With the two closed valves and a certain amount of air (diesel cycle) or explosive mixture of air and fuel (Otto cycle) already compressed large temperature arranged to be inflamed and perform the motor race.

It is at this time (theoretically) that causes fuel injection (diesel cycle) or sparkling jump in the spark plug (Otto cycle) causing combustion of compressed gases and increasing pressure on the piston's head.

The pressure is the one that pushes the piston towards the PMI in his motor career (combustion race). Once this point, the exhaust valve (theoretically) opens and the piston is directed to the PMS expelling the gases and burned from the cylinder and preparing for a new work cycle.

As you have been able to read, (it takes good note) in each work cycle the crankshaft tour 720º (two laps) and each piston ago two PMI and two PMS.

The moment we are looking for to hear the engine, is the combustion moment of the first cylinder, that is, the second PMS with the two closed valves. (since in the first one it is actually the crossing of valves in which Escape has not finished closing and admission begins to open)

This moment is easily found if you know

how The opposite (both cams steal their taitas).

In an OHV engine (block camshaft and valves in cylinder head) this is known by tantling the tachies, if you are at the point you are looking for, the two sneakers of the first cylinder have slack while those in the room are slightly pressing the valves slightly.

An issue that will always serve you: turning an engine in its direction, the first valve that will open while both closed is escape and then admission.

This serves to determine the direction of rotation of a four -stroke engine (which in the case of cars is normally right from the distribution side).

I recommend that you visit the page www.todomecanica.com and download the savapantallas of Deutz.

I send you the link:
www.todomecanica.com/deutz-egine-screesaver.html

are 42 megabytes, but it is the best assembly animation and work cycle (practical) of an indirect gas injection engine (Otto cycle) of four cylinders online, Dohc 16V 16V distribution, and trees drag per chain per chain that I have seen (and I have seen quite).

You can also monopolize knowledge on that website, although I am not a moderator I am a user.