very simple, finding TDC on the standard way , as I described extensively before. By finding the point where the piston is on its top in rising. I could also try the piston stop way, as it is very simple as well. But I would expect that to give the same reading as to what I already did. The way you describe is much more sensitive, as the dial has to be perfectly aligned for the same amount of valve bucket rise as asked by the manual. But as it is another way, I will have to try it to be sure what is going on.
Nowhere in recent posts did I explain how to find TDC. You have a serious misunderstanding of the entire process and I strongly suggest you have someone qualified do it for you. Best of luck.
Oh, but you can find TDC the way you described. Or at least get very close. If you know the degrees at which valve lift is say 0.050, which can be found in the manual (or comparable heights and degrees), you know where on the degree wheel you are, and you then can calculate at what point TDC is. Only thing is that you have to assume that degreeing in the first place was not necessary, as any faults are taken into the equation as well. But that method could be used to compare the degrees off, between my TDC and the calculated TDC. If my intake opens 20 degrees later then in the manual, and my TDC is 20 degrees off as well, I at least know that my TDC is correct they way I found it already. So I thought it was a clever way to check my TDC. Not to pinpoint the exact location, but at least I would know that my measurements were right. But I understand that it was not your intention to suggest that. I would really benefit from someone pointing out what I did wrong in finding TDC as I so extensively already described above. As I clearly have no idea what I am doing (here), as I have a serious misunderstanding of the entire process I just heard. I am very curious how someone qualified would find TDC other than the 2 methods widely used (dial gauge and piston stop). I would assume that he would already know what went wrong when he read my TDC-finding actions. Finding TDC is not really rocketscience to be honest, so my mistake must be very stupid, surely. Too bad nobody has seen it.
There is exactly 2 methods to find TDC: 1) Use a dial indicator which body threads into the spark plug hole (Hill makes a great tool). Rotate the crank until the piston contacts the probe of the indicator. As the piston comes up, watch the indicator, as soon as the values start to decrease you are at TDC (change in value). Note, the 355 motor has 1 degree of dwell so if you want true TDC you need to split the dwell in half. 2) Use a dead stop threaded into the spark plug hole. Turn crank one direction until you hit stop. Mark angle. Turn crank the opposite direction until you hit stop again. mark angle. The difference in the two angles is TDC (measure angles via degree wheel on crank)
Thanks. I have done the dial way, will now find a way to do the piston stop way. Variaton on that is a combination of the 2, where a rod is inserted in the spark plug hole, and travels up till it reaches the dial indicator, and its hand starts to move. Note the degrees, and turn CCW to the same point (different stroke of piston) where it also hits the dial gauge. Add those numbers, divide by 2, and that is the number your TDC is off from true tdc. Adjust the wheel and measure again. And I think that is what I will be trying tonight.
No, you are over thinking it. The dial indicator will stop once the piston reaches TDC. You continue to rotate the crank for 1 degree and the dial will not move. After 1 degree it will move again. The 1 degree is the dwell. So, just find were TDC starts, find where it ends, split the difference (1/2 degree). You are only looking at the piston and the crank at this point so belt slack does not come in - really does not matter which way you rotate crank.
I know it's one degree because I have measured it. But, it could be slightly different from motor to motor based on manufacturing tolerances.
Ok, new info. On bank nr 2 (5-8 ) I have found TDC. I first lined the marks up on the cam and housing, as a start. But I noticed that the intake lobe on valve nr 1 was already pushing the bucket down a little. That is odd, should not do that as far as I know of engines (but hey, I need someone qualified to figure that out as well). Looks like the marks are on the wrong side!! So I turned another 360 degrees, and found TDC again. Just a little fact, TDC on nr 1 and nr 8 on a 355 engine are only 90% apart, and my TDC's were also. Could it be that my TDC was right after all? So I continued , with the cam marks NOT visible as they wer ein the wrong cycle. I then measured the degrees at which the intake valve opens and closes, and hey, only 2 resp. 1 degree off of the 56 and 108 degrees. My conclusion: the cams are timed more or less correctly, but the marks are way, way off. On nr 5-8 even almost 360 degrees. How is that possible??? I will post some pics of the cams tomorrow at both TDC's so you all can judge for yourselves that at enlined marks, the lobes are not in the correct position..
I have degreed the 5-8 intake cam, as said nairly spot on to my TDC. Hard to believe that is a coincidence. Will read the chapter in the WSM tomorrow It is bedtime over here, will post some pics tomorrow of lobe positions at TDC and at factory marks. I hope you all will respond. Thanks sofar.
Be very careful, this was a job I could not do. Lucky I caused no harm. I think out of the car I would have been more successful!
Ok, more info. I hope you all can help me with this, much appreciated. Been working on cars for over 15 years, but this problem is new to me (last project was a Porsche 928 gearbox + torque tube which I had to put new bearings and seals in). By the way, at thgis point I am only checking the present situation with the old belts and tensioners. I have not fitted new ones yet. The following pics show the situation when the nr 8 piston is SUPPOSED to be around TDC, as the markings line up. (not true TDC I know, but should be very near normally). But as you can see, the outlet valves are having FULL lift!!!! The cam lobes are fully depressing the valve buckets, full lift. Full lift on a valve, with the piston on TDC is not possible. Would mean collision! SO, the markings cannot show TDC in this case, they show a completely different point on the stroke of the piston. Vice versa, when TDC is MEASURED with a dial indicator, it is not on those markings, but like 35 cam degrees off of the marks. Other important point, when the 8 piston is on its markings as in the picture, the nr 1 piston on the other bank is only 4-5 mm off its markings. Should be 45 cam degrees (say 2 cm) , as that is the Ferrari crankshaft layaout (90 crank degrees). So is it possible that the markings on this camshaft are not for the nr 1 and 8 cilinders, but for other cilinders? Like 2 and 7? Anybody ever experienced this? The check I did yesterday on opening and closing of the inlet valve nr 1 while using my MEASURED TDC, was nearly spot on to the Ferrari data (32 and 112 degrees, I found 34 and around 110). Ok, any thoughts on what is happening please!! Image Unavailable, Please Login Image Unavailable, Please Login
The rod is still in there after the measuring with a dial, now it is resting against the side. When I measured for TDC it was straight in the middle of the hole and connected to the dial. And isn't it so that for timing bank 5-8 TDC on 8 has to be found? Not on 1. Or am I wrong?
if that is true, would it be possible that my cams have been switched? I mean right side cams on left bank and vice versa? Then the markings would be out for sure. Question is, would that fit and work? The basic form of the cam should not differ much I would think?
I think you are missing this: the factory marks are for the entire engine, both banks when cylinder 1 is at TDC.
"the factory marks are for the entire engine, both banks when cylinder 1 is at TDC" Ok, now we are getting somewhere! Thanks for finding my mistake. I have done twin cams before, but no quad cam, so there I made a mistake on the meaning of the marks on the right hand bank. So I went to work again: I set nr 1 to Measured TDC and the lines on the other bank almost lined up, very, very close. Only 9 degrees on the crankshaft, so that sounds good. Explains also why the opening and closing of the inlet valve on #8 was almost to factory spec, as that one is nearly spot on. Now there can be 2 conclusions : - Measured TDC on # 1 is correct as valve opening/closing of #8 is correct, and RH Bank marks (more or less) do line up. - As Measured TDC on #1 is correct as concluded above, the marks are way off on that LH bank. Would the engine run when marks are 5mm off on the cam ? Or would it run, but not very nice?
Several people have told you that your method of finding TDC is flawed. Your timing marks are close, but don't line up all that well. If you cannot see the correlation you should probably get someone who knows what they're doing to do the work.
I really do not get it. What is wrong with my way of finding TDC? No one has told me what is wrong specifically, other than that it is not good and that I should seek professional help with finding TDC. What is so special about this engine that the normal ways of finding it do not work? I have made one mistake, and that was that I did not know that on TDC of 1-4 , both the markings on 1-4 as well as 5-8 should line up. I thought that I needed TDC on 8 seperately for the markings on 5-8. Other than that, I really do not see what I did wrong. There are several ways of finding TDC, and there are several ways of checking the cams on degreeing. I know that on the 355 some prefer the lobe centre line. I know how to do that. I know I have to check for 103 degrees and 110 degrees for inlet and exhaust. I have the tools, and have done it before on twincams. Look, I really appreciate it when people take their time to explain or help. But if that help consists of "go see specialist" then I am not really helped. I like to learn, and in this case it is no different. I really want to know what I am doing wrong. Otherwise I cannot learn. And see it this way, if I made a mistake, other people can learn as well from that mistake as long as it is explained... So please...
What I don't understand is 103 and 110 degrees. The timing is set as a relation to TDC and the intake has an advance of 16 degrees and the exhaust has a retardation of 16 degrees. And, you measure the side lifter of the intake as the center is retarded 10 degrees.
