Ok, bij deze..........
First off you must understand the basic idea of how a 4-stroke internal combustion engine operates. Hopefully you already understand this before you completely rip apart your engine! Bruce Andersons “Performance Handbook” has a very good section, which gives a detailed description of how and why valve timing is so important. For sanities sake I will not go into a step-by-step detail about the cam timing because it is covered in such detail in every manual out there. I would like to give an explanation of “what your trying to do” in normal language to hopefully clear up a bit of what the manuals don’t get across too clearly in my mind.
First it is necessary to “Rough time” the engine. Rough timing of the engine is accomplished by eyeballing the position of the camshafts in relationship to the crankshaft. First thing to do is to turn the crank to TDC. That means (in theory) that the #1 and #4 cylinders both have pistons at their full extension. So, how do you get the #1 cylinder to TDC? Simple, first Install the crankshaft pulley on the crankshaft. Notice that there is a dowel pin that dictates how the pulley goes on the end of the crankshaft. You can’t mess it up; it’ll only go on one way. Now, on the face of the pulley there are 3 marks, one of them has “Z1” marked next to it, that is your TDC mark. So, simply rotate the crank until the Z1 mark is matched up with the seam in the crankcase. (There is also a notch in the bottom of the fan shroud if you have it installed.) Once these are lined up your crankshaft and pistons #1 and #4 are now at TDC.
I found that the best way to figure out which stroke the cylinder is on (compression or firing) during this whole process is to install the distributor and use the rotor as a guide. To set the distributor to #1 firing stroke is easy. Simply set the crank to TDC, get the distributor shaft started in the hole (with new o-ring installed of course) and roughly point the rotor where the #1 spark plug wire would normally go into the distributor cap (if it were installed). The rotor should be pointing at something like a 45 deg. angle up and away from the engine. When you seat the distributor fully into the case, the worm gear on the crankshaft meshes with the gears on the distributor. It takes a bit of playing with it to get the rotor to point in the proper direction. The Pelican Parts Tech Article on Setting Static Timing gives a detailed description of how to set the distributor.
With the distributor rotor pointing as described, the engine is now at #1 TDC firing stroke. If you were to rotate the engine 360 deg. at the crankshaft, from this point, the rotor would now be pointing 180 deg. from where it was. And now the engine is on #4 TDC firing stroke and #1 in at TDC compression stroke. If you understand these two things than you can time an engine.
Once the cams are installed and have been sealed to the cam chain housing you need to get them roughly pointed in the right direction. (Image) On each cam there is either a number or a dot stamped on the face. This number or dot must point up. With the cams pointed up (chains not attached) and the crankshaft at TDC, your engine is now rough timed.
Now that the motor is rough timed, assemble the gear flanges with the woodruff keys on the cams and install the gears on the cams with the chains.
The cam gears are kept in position by the use of the little dowel pin that locks the gear flange with the gear. There are 17 holes around the circumference of the gear. When you are timing the cams, you are doing so using a method that measures the amount of overlap of one valve on each bank of cylinders. These measurements are taken with the use of a dial indicator on a special “Z” mount. (Fortunately you can pick up a dial indicator for around $30 or so and I believe Pelican carries the indicators and the Z mount. I would suggest buying a Metric dial indicator; it makes the process much easier without having to do conversions.)
You are attempting to set timing on one bank of cylinders at a time. Starting with the left bank, position the dial indicator with about 10mm. of preload so that the indicator needle is resting on the cylinder #1 intake valve cap. When you have the crank at TDC and the left banks camshaft pointed up, and the dial indicator set on the valve cap, you are ready to time the cam on the left bank. (You can either install the tensioners at this stage, which is what I did, or you can use a long screwdriver to keep pressure on the idler arm, which will keep the chain tight.)
With everything ready to go on the left bank, insert the small dowel pin into whichever hole is lined up (It’ll make sense when you see it) and hand tighten the large nut and washer. While you tighten the nut you don’t want the cam to move even the slightest bit. Once you think you have it set as best you can by eye, you turn the crankshaft exactly 360 deg. while watching your dial indicator. (In your manuals it will give you a certain value of overlap in millimeters for your specific motor and camshafts; for my 3.0 it is 1.55mm.) That’s what you are trying to get on the dial indicator. If, after spinning the motor exactly 360 deg., you get a reading higher or lower than what is called for, then the dowel pin will have to be removed and relocated to another hole. This is more less a trial and error process. It took me several times to get it down right. When you can rotate the crankshaft 360 deg. and get the exact value that is needed that bank is now timed properly! All you have to do is torque the nut and re-check to make sure nothing moved. Now you just move on to the right bank of cylinders and repeat the whole process.
(Remember that when the crank is set to “#1 TDC firing stroke”, if you rotate the engine 360 deg., that now even though the crank has made one complete revolution, you still need to turn it another 360 deg. to get back to your starting point of ”#1 TDC firing stroke”. It takes 720 deg. (two complete revolutions of the crankshaft) to get from #1 firing stroke to #1 firing stroke again because it is alternating with the #4 cylinder.)
Hmm, ik zie nergens staan dat je de klepspeling op 0,1 mm moet zetten, dat doe je dus voor cilinder #1 wanneer die op onsteken staat en andersom. Dus nokkenassen monteren met punt/getal omhoog, krukas op z1, klepspeling #1 0,1 mm, krukas 360 graden draaien, linker nokkenas op tijd zetten, klepspeling rechts stellen, 360 graden draaien, rechter nokkenas stellen, alles goed vast zetten. Tussendoor moet je natuurlijk wel de nokkenassen zodanig vastzetten dat ze bij het draaien van de krukas niet kunnen verdraaien.
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