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Degreeing cams

Discussion in 'Technical Q&A' started by fatbillybob, May 2, 2007.

  1. fatbillybob

    fatbillybob Two Time F1 World Champ
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    O.K. here it is. There is much controversy and holy war over degreeing cams. These are 2 ways of degreeing a 4 cam Ferrari motor that work for all engines and the little tricks that make Ferraris special. This was done engine out on a 348. I assume some knowledge and hope this fills in the blanks for those interested. This is not the only way and there are other degree wheels etc. that can make things easier or harder depending on your point of view. Some of this is a repeat from the previous thread on cam set-up so that all the basics are in one thread. Enjoy and feel free to chime in.
     
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  3. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #2 fatbillybob, May 2, 2007
    Last edited by a moderator: Sep 7, 2017
    Specs: WSM lists Intake open @14* closed @ 53* Exhaust opens @ 53* closed @ 10*
    States .020”
    From this you can calculate Intake Duration of 247.00 degrees (14*+53*+180*) and
    The Exhaust Duration is 243.00 degrees (53*+10*+180*). Overlap of 24.00 degrees (14*+10*). The Inlet Cam has an Installed Centerline of 109.50 degrees ATDC [(14*+53*+180*)/2] –14*=109.5. The exhaust cam has an Installed Centerline of 111.50 degrees BTDC [(53*+10*+180*)/2] – 10*= 111.50*.
    These are the basic facts you need to degree your cam by either of 2 popular methods. Why 2 methods? You can use either method but the reason for using one of two methods is because of Ferrari uncertainty in how it lists specifications and interpretations from italian to english and issues with post 355 cars using hydralic lifters which cannot be removed easily and replaced with a zero lash solid lifter like a 350 chevy motor.
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  4. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #3 fatbillybob, May 2, 2007
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    So looking at the cam profile you see the lobe centerline which is the point of maximum valve lift. You see the opening and closing ramp which can be different thus an asymetrical cam profile or the same for a symetrical lobe. The lash ramp is also called the clearance ramp. The valve tappet surface to the lash ramp is the valve lash or clearance. This is here to compensate for expansion of the engine parts when the motor is hot ideally resulting in zero lash at full operating temperature.

    Cams can be timed by just using the timing marks but you may be off a few degrees which can effect how the engine runs in a negative way. By degreeing cams you remove as much guesswork as possible as to the perfect running of the car as Ferrari intended.
    Cams can be degreed by the “open/close” method or the Lobe centerline method. We will go through both methods timing the 348 DOHC motor. These concepts work for all motors.
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  5. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #4 fatbillybob, May 2, 2007
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    You will need these items:
    This is a homemade TDC plate of just ¼”x6”x2” steel bar stock with a hole for the threaded rod to touch the piston top and holes the dimension of the cam cover studs to anchor the bar.
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  6. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #5 fatbillybob, May 2, 2007
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    Here you can see the TDC plate and three large nusts on each cam cover stud to raise the plate high enough so it will not be hit by the cam lobes as they rotate.
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  8. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #6 fatbillybob, May 2, 2007
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  9. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #7 fatbillybob, May 2, 2007
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  10. snj5

    snj5 F1 World Champ

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    #8 snj5, May 2, 2007
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  11. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #9 fatbillybob, May 2, 2007
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    You need a degree wheel. Summitracing.com makes their own and it fits the 348 crank snout without modification. Remove the damper and bolt the degree wheel right on the end of the snout. I have already found approximate TDC within 5 degrees or so. My pointer is at 9 o’clock out of convenience so my wheel O* TDC is at 9 o’clock too. If you hold the wheel here and impact wrench the crank bolt tight with 2 quick pulses of the air gun it is tight enough to not move and tight enough to move the crank clockwise and counter clockwise with no issue.

    Both methods of degreeing cams demand that you find TDC (top dead center) of a piston on the 1-4 bank. It does not matter which piston but usually the #1 piston is used. Once this bank is timed you must find TDC on the 5-8 bank in the same manner. I use #8 because it is closest to the degree wheel.

    When turning the crank try to stay in the driven direction which is clockwise. If you go counter clockwise it is o.k. but it creates slack in the timing system that needs to be taken up as you work. Your engine should be set-up for TDC by a degree wheel and dial guage even if you time with just the cam marks on cam cpas. This should be set-up already just to proeprly place the timing belt. So you should know your TDC if you are starting to degree cams.

    Finding TDC: Turn motor clockwise watch piston rise on the dial guage you can see the cam marks starting to line up then you know you have piston in compression. If you do not see the cam marks coming you are off one cycle keep turning. When you see the rise “peeking”… stop. Zero your dial guage. Crank the motor CW so the dial guage reads .050” Lets say it says 12* on the pointer/ degree wheel. Crank the motor CCW so the dial guage reads say .090 the other way. You need to overshoot in the CCW direction because you need to take up the timing slack. Now crank CW to .050 again. Lets say it says –10* on the pointer/ degree wheel. –10 + 12 = 2. You have now taken readings on either side of approximate TDC.2/1= positive 1*. Therefore, True TDC is at 1 on the degree wheel. Now crank the motor CW until 1 shows at TDC on the degree wheel and the cam timing marks should be nearly spot on. You can see the dial guage register maximum and you have ensured that you have taken all slack out of the timing system. You can now bend the pointer to read 0* TDC and from here on this will be your true TDC referrence point.
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  13. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #10 fatbillybob, May 2, 2007
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    Now we get to the good stuff!

    Degreeing cams by the “opening/closing” method: You are now at TDC and the cam marks are almost spot on. Set-up dial guage and holder bar onto the third row of cam cover studs and set-up dial guage pointer on edge of #1 intake valve tappet. Make sure dial guage is in line with tappet opening and closing. The tip of my pointer is bent to touch the tappet surface while the guage is parallel to the valve bucket movement. A nipple usually unscrews off the tip of the guage pin and I just screwed in welding rod for a custom bended extension.
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  14. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #11 fatbillybob, May 2, 2007
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    Crank motor CW and watch the cam move from the base circle causing no movement of the dial guage to the clearance lash ramp causing no movement to just the beginning of the opening ramp. At the start of valve opening the degree wheel reads 28* in my case.
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  15. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #12 fatbillybob, May 2, 2007
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    As I continue to crank CW the valve closes. When is just starts to end all of its movement at the end of the closing ramp that number is 106* on my degree wheel.

    The Ferrari specs are 14* and 53*. What’s wrong? Nothing! Ferrari must be giving their specs in camshaft degrees which are ½ crank degrees. So my intake is opening and closing At 14/53 per the manual. This means the cam marks in my car are spot on for the 1-4 intake cam. Each cam manufactuer and car manufacturer list their specs differently. So you need to figure out what they are doing so that your numbers make sence. Going through the same exercise with the exhaust cam means moving the dial guage rig and setting up on the exhuast cam #1 tappet and doing the same thing. Again my cam marks are spot on. To degree the cams on the 5-8 bank you must find TDC on any 5-8 piston. I choose #8 because it is closest to the degree wheel. #8 TDC happens to be 90 degree off from TDC of the 1-4 bank… this is a V-8 motor and that is the Ferrari layout.
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  16. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #13 fatbillybob, May 2, 2007
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    This time I used a heavy block of steel laying on the header to support the dail guage assembly. I was lazy. TDC 5-8 is established. You crank the motor CW again reading the intake cam with open 14 close 53 and then do the same thing on the exhaust cam with 53 opening and 10 close. Again my cam marks are spot on. I basically have done all this work just to prove that my cam marks in my engine are perfect.

    Lets talk about problems with this method and Ferrari. First the American car makers are known to use zero lash on the tappet to clearance ramp gap. They also use the number of degrees on either side of .050” to establish cam duration and degrees of opening and closing on the cam. You see if they started the “opening” number of degrees as soon as the transition of the “clearance ramp and opening ramp” and “closed” degrees at the transition of the “closing ramp and clearance ramp” it is very hard to see this small change on the dial guage but if done this way the full cam duration is known. This is also called the advertised duration of a cam in American cam terms. Ferrari does two funny things on my motor. First in the manual they refer to .020” number with no explanation. In fact they say, “bring the valve clearance of no1 and 5 to 0.5mm (.020”). It this what they want or is this a bad Italian translation? Here is how I figured it out. First my valve clearance is .020” on the intake. Using .020” valve lash and the procedure described above reading the dial guage at the transition of the “clearance ramp and opening ramp” and transition of the “closing ramp and clearance ramp” gives perfect results. I tried to do the same degreeing procedure with the lash set at zero by using my feeler guage to close the lash.
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  17. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #14 fatbillybob, May 2, 2007
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    The result is that the opening and closing come much too early and if Ferrari wanted to use zero lash the manual specs would be different. I further explored the .020” number assuming that Ferrari chose to use a duration and degree specs based on and .020” opening and closing rather than the American .050”. When the degree proceedure is done with opening/closing A .020” again the numbers come up completely wrong. Therefore, Ferrari cam numbers based on full duration with tappets at the installed clearance. Still I have questions because my numbers were perfect and my exhaust clearance is set to .035” not .020. So when Ferrari also quotes .020 I have no idea what they mean.

    As you can see this method has questions or problems because of poor documentation by Ferrari. We can completely avoid these issues by using method 2 degreeing cams by the lobe centerline method. But we have to assume that the Ferrari 348 cam lobe is symetrical. If the lobe is asymetrical then you must time by the open/close method.

    Next installment the "lobe centerline method" of degreeing cams and avoiding all these problems.
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  18. spider348

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    Fatbillybob, thank you. A couple of dumb questions.
    1. How did you establish the correct Ferrari 14 and 53 degree requirement from your degree wheel reading of 28 and 106 degrees? I am not clear how this correlates.
    2. Appears you were able to correctly degree your cams with the respective valve shim clearance at the standard factory specification. There was no need to shim to a specified clearance amount such as the 0.5mm you reference? As you point out, I do not fully understand the factory manuals instructions.
    Look forward to your next installment.
    Thank you again, John.
     
  19. Artvonne

    Artvonne F1 Veteran

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    With the accuracy established, it would appear the 348 has much more accuracy to its index marks than the 308s of the 70's vintage. Neither one of my two are even accurate as to TDC marking. My later car indicates 3 degrees retarded after the indicator plate was shoved over as far as it will go in its slots. Imagine what this does when your trying to set maximum ignition timing advance, and the flywheel marks your using are off 5 degrees retarded to start with!

    With all four cams degreed, the rear intake cam index marks on #21645 are about 3/32" behind the alignment mark, or, about 20 degrees off! The other three cams are much closer but none are right on. And trust me, I checked and quadruple checked, its right. And thats after I took out the 5 degrees the TDC mark was retarded. So while you can probably get away with just setting up all your marks on the later model cars, the early ones could throw you some real curve balls and youll maybe wonder why your car runs funny. If you can at least go through this procedure once to verify everything, and know that all those index marks are correct to begin with, or make your own new marks for future reference, at least then you will know. After that you can just throw on belts and skip all this degreeing BS if you want. You can also pass along this data with the car to the next owner, saving them the trouble of going through it.

    I locate TDC a bit differently. I use a piston stop in the spark plug hole that physically contacts the piston, and gently bring the piston up to it until the motor stops. You dont force or jam anything, its all done very gently. These tools came in the tool kits in older vintage cars, and its how you find TDC on other engines such as OB motors and some aircraft, so its not like some crude way of doing things. I try to find a point that stops the motor about 10 degrees either side of TDC, mark it, roll it around backwards, mark it, and split the difference on the degree wheel. If your flywheel TDC indicator is not perfectly aligned, you need to alter it to the new position, or make a new reference mark if you want true accuracy.
     
  20. ernie

    ernie Two Time F1 World Champ
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    YES SIR!!!! That's my boy! great write up chubby!

    Ah ..... it's great to be a stooge, ain't it. :D

    As the fat one has just shown, the cam marks on the 348s are just about dead nuts on, if not perfect. I got into a tiff about this years back with someone, when explaining the belt change on a 348. I have long said that, for a ROAD car, all you really need to do is find TDC, and then set the cam marks up to the marks on the cam caps. Again this is the quick and easy way to do it. I was told this by a very old school Ferrari mechanic.

    Why do I advise this?

    I'll tell you why. Because when most people get their cams adjusted the clearances between the shims and the cam are "ball parked". Meaning, that when Ferrari gives the specs for the intake cam of between 20 - 25, if the gap is let's say 23 most will call it a day. After all the clearances fall between the two spec values. They don't go the extra mile to get the cam clearances dead nuts exact. Which is what you need, and what is a pain in the ass to do. It's a pain because the value printed on the back of the shims are NOT exact. You MUST use a micrometer to find EXACTLY what the thickness is, of EACH shim, in order to get the clearance perfect. Trust me on this, unless you have buck loads of shims at your disposal your are not going to get the clearances of each and every valve perfect.

    Some of you may still not be understanding this and I'll explain more.

    Hear is the deal, even though you may have timed your cams PERFECT, it does not mean that ALL the valves are opening the EXACT same amount. If your cam gaps are "ball parked" they are all not opening the same amount, nor are they opening/closing at the same time. The reason is because of the tiny difference in the cam clearances. In order to extract every last ounce of power from the engine everything must doing the EXACT same thing. Now lets say the clearance for the valves goes something like 20, 20, 21, 23, 20, 24, 22, 20. They all fall within the factory specs of 20-25 but they are all not opening and closing at the same time. The valves that measure 20-21 are opening before the valves that measure 23-24. This is because there is less space between the cam lob and the shim/tappet, so the cam lob comes into contact with the shim sooner. Like wise, on the valve that are 23-24, the valve will close sooner because the cam lob loose full contact with the shim sooner, because there is more space in between the cam and the tappet. Then we have the area of cylinder compression and valve leak down, which is a whole other subject. Or even the tuning of the injectors, yes injectors can be tuned to spray the exact same amount, which NO Ferrari dealer I have ever seen does.

    Soooooooooooooo................

    Unless you are going to make sure that EVERYTHING is EXACTLY right on your 348 engine, why waist all of your time to find out what FatBillyBob just proved? That the marks on the cams and cam caps, in his 348, are right on the money. Maybe you should do it the first time, just so that you know. But other wise, in my opinion, for a road going car that is not going to be professionally raced, why waist all of that time?

    As for me, I'm keeping it simple. Finding TDC, setting the cam marks up, and forgetting about it.

    Again chubby, AWESOME write up! I can't wait for the second method!

    You gotta love the Brotherhood. Stooges rule!
     
  21. fatbillybob

    fatbillybob Two Time F1 World Champ
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    First no question is dumb. Its dumb not to ask it. Anyway the cam turns at 1/2 the crankshaft speed. So on the summitracing degree wheel it just lists degrees as shown. The Ferrari spec is 14/53* at the cam. Therefore you need to half the degrees you see on the degreewheel since crankshaft turns twice the cam. Some other makers degreewheels account for this and will show the crankshaft degrees on the wheel on the outside and camshaft degrees on the inside.

    Agreed. I don't understand the factory 0.5mm issue either. But not to worry. First, all cam marks line up, second my degree wheel at installed valve lash work, and the third check will be in my next instalment the "lobe centerline" method. So I will confirm cam timing 3 ways.
     
  22. fatbillybob

    fatbillybob Two Time F1 World Champ
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    I had a 78 308gts and still have a mondial QV cab. Those marks are as good as the 348 in my case. I think the older the cars are the more they have been molested. Guys have broken belts and rebuilt parts, decked heads, shimmed cams, shaved heads, altered cam profiles sometimes on purpose and sometimes unintentionally. All kinds of things can make these cam marks not valid including factory stupidity. I have seen very few like 1-2 cars of all the ones I have doen be off the mark. I may not have enough experience. Making new marks under your conditions is a great idea. I also think contray to some other experts on FC that marks alone can be very accurate. But really if you are degreeing to get TDC then confimring timing with a degree wheel is easy as I have shown here. The hard part is adjusting if you are off. Lets take a 25.5" camshaft and 360 degrees means that if your cam had 360 marks each mark would be 1* = 0.25mm That is huge! Even an old guy with bifocals can see a quarter mm. So just using science of only being able to read 1/2 of an increment means your accuracy from marks alone can be 1/2* for a 1" diameter camshaft! If the shaft is bigger in diameter it is even easier!

    As to your method of finding TDC...Yes your method works too. In my pictures above you see that my pushrod is threaded. It is threaded because sometimes I just use that wing nut you see and another nut on the threaded shaft to use my TDC plate as a piston stop. The emthod I use depends on how I feel that day. I never use use whistles or any of the other gimmicky ways. It is either piston stop or dial guage for me.
     
  23. Mark 328

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    FBB:
    That is a great detailed write-up and I (we) really appreciate you taking the time to write it up.
    For setting the valve timing, I agree that everything should be rotated CW (as the engine rotates), but for finding TDC, wouldn't there be less “slack error” if the crankshaft is rotated the engine CW to the degree wheel mark on one side & CCW to the other?
    In your description, the crank is rotated CW to each mark; this would have the piston (and resulting slack) pushing down on one side and up on the other. It seems like it would be more accurate (from a slack impact minimization point of view) to be pushing the piston-up on both sides of TDC? This is how Paul described it using the piston stop method.

    Mark
     
  24. Motob

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    The Ferrari specs are for degrees of rotation of the crankshaft, not the cam. These specs are only valid with both the intake and exhaust valve clearances set at .020" (.5mm)

    Brian B.
     
  25. fatbillybob

    fatbillybob Two Time F1 World Champ
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    Yes I hear you. I do not know. First the method I describe is they way it is done in the industry so I did not invent it. And Paul's piston stop method is an accepted industry way to do it too. I suspect the reason for the difference as you describe is that in the dial guage method we are only moving .050" off "predicted TDC". Moving only .050" ccw would barely take up the slack as you say with a very narrow range of degrees on the degreewheel. So you need to make up for that by going ccw like .090". Also, I think you want TDC in the driven direction cw. This accounts for all the wear in your engine. I acutally like this method better for exactly the reason you state. I think there is more accuracy this way. The piston stop method will move the degree wheel over a much larger range of degrees then divide by 2 = TDC. This works because of the larger range. Large range minimizes the effect of the tiny slack. So really either way works. The only other comment I can make is that the TDC I found has caused all my cam marks to line up spot on. I am sure the piston stop method would have been perfect too.
     
  26. fatbillybob

    fatbillybob Two Time F1 World Champ
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    You could read the workshop manual this way but that is not what my motor proves. Set clearnaces on the inlet side .020" makes sence as this is an installed target. This does not make sence on the exhaust since the installed clearance is .030-.040" depending if cat or non-cat 348 although .020" could be installed just for timing. I doubt Ferrari would do more work to change it back to the installed target lash after degreeing. I hear what you are saying and had to prove this for myself. Tappet clearnace on the exhaust at .020" changed the degree readings off Ferrari specs just like when I verified that zeroing the clearance did it too. I am not sure how you can get degrees of rotation at the crank vs. the cam. It does not make sence because the cam degress would then be 8 and 22.5 on the intake for example. This is way out of the range of any motor I know of. You can read the Ferrari specs at the crank on "some" degree wheels that are so marked to account for the fact that the camshaft rotates at 1/2 the crank speed. I think Lunati makes their wheels like this. Two things tell me I am correct. First all the factory marks line up which would not happen if I read Ferrari specs from the crank with a generic degree wheel. Second the "lobe centerline" method will prove it. In my next installment. This is discussed in my problems section above and is subject to much argument. But it really does not matter since the lobe centerline method takes tappet issues completely out of the equation as well as reading based on Cam or Crank. Stay tuned!
     
  27. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    FBB -- I think you misspoke some units (and magnitudes) in your last post -- the intake side is in the 0.2mm range and a typical exhaust tappet clearance is 0.3 ~0.4 mm (not .030"~.040") so the 0.5 mm measurement spacing is still a little larger.

    IMO, using zero clearance (by sticking a feeler gauge in) and then measuring between the 0.5 mm lift points is what the Designer was trying to say in the text (and would do because it's easier ;) and is mathematically equivalent to the "set to 0.5mm clearance and measure between any detected motion" method), but it got slightly changed in the translation.

    However, I understand your report that all seemed OK at the operational clearances. If you can put data together describing the measurement method used, beginning, center, and end events, please do -- it's interesting work and I appreciate your making the posts.
     
  28. fatbillybob

    fatbillybob Two Time F1 World Champ
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