Question on 575 cam timing section B3.02 camshafts provides timing data Intake start before TDC (AA) -7 ± 1° end after BDC (CA) +56 ±1° Exhaust start before BDC (AS) +36 ± 1° end before TDC (CS) +13 ± 1° From this it appears that the exhaust closes well before TDC and intake does not open until 7 degrees after TDC as measured by degree wheel on crank. But then Checking timing • Fit tools AM 105165/21 and AM 105165/20, modified as previously described, onto the engine. • The reference marks for the shaft timing must be aligned with the relative caps. The pulleys must be temporarily fitted with the belts tensioned ( A 3.03). • Position bank 1-6 cylinder no. 1 piston at T.D.C. during combustion and secure the base (I) of a dial gauge (L) on the head, intake side, with the feeler pin resting on the upper surface of the bucket of one of the two cylinder no. 1 side valves. Image Unavailable, Please Login • Reset the dial gauge indicator (L): in this position, the buckets can rotate freely in their housing. • Have the crankshaft rotate clockwise (ca. 360°) thereby approaching the crossover phase, and check to ensure that the dial gauge (L) is still showing zero, before the crankcase starts opening the valves. • Rotate the crankshaft until you read the T.D.C. on the dial gauge (X) • In this condition, the dial gauges (L) and (X) and the goniometer on the crankshaft must indicate “zero”. • Rotate the crankshaft in a clockwise direction until the dial gauge (X) reaches a value of 2.43 mm (corresponding to 18° after the T.D.C.) • The dial gauge (L) must now show a value between 1.44 to 1.59 mm. • Anchor the dial gauge base onto the exhaust side of cylinder no. 1, with the feeler pin resting on the upper level of the bucket of one of the two exhaust valves. • Rotate the crankshaft further until the dial gauge pointer (L) has stabilized on a certain value and the bucket is free to rotate in its seating. Under this condition, the dial gauge will indicate a value range of 1.51 to 1.66 mm. From this it appears that intake does indeed not open until after TDC, but the exhaust closes after TDC. Can someone clarify for me? thanks
and if the 575 is similar to the 550 I would have expected what john cribb measured for a 550 Image Unavailable, Please Login
The only way I see to make camshaft numbers agree with cribb data (which is what most engines usually look like) is for the numbers given are for camshaft degrees which are 1/2 crank. And the end of Exhaust should be end AFTER TDC And then the "zero " point for the L dial gage is actually around 0.7 mm lift to start with. Then there is a crossover phase.
But the directions to move gage to exhaust side and rotate crank past 18 ° and get a reading of 1.51 to 1.66 mm makes no sense to me.
Ferrari's timing method is measured on the ramps of the cam, not the top or bottom of the cam, where cam profile is changing so slowly it is difficult to get an accurate reading. The cam timing at top is the true timing, and using the ramp method Ferrari recommends is more accurate than trying to guess where the cam lobes peak.
Terry do you understand moving the gage to exhaust side, and going past 18° and getting minimum 1.51 mm of cam bucket movement. At 18° past TDC there is likely less than 0.2 mm left for exhaust travel. I think I will set all marks dead on, rotate crank and watch intake open and close and the do same for exhaust and see if those numbers make sense
Ferraris cam timing numbers are always in crankshaft degrees. In the old days (before hydraulic lifters), they would have you set the valve clearances at .5mm and the cam timing numbers would match up with the moment the cam actually just touched (started to open the valve) or as it lifted off (started to closed the valve). They did this because at .5mm of clearance the lifters would not touch the cams until they were at an accurate point on the ramps for cam timing. Now since they have hydraulic lifters, you cannot tell when the cams are just opening the valve, so they have the complicated process with the dial gauges to make sure that you are on an accurate point on the ramps for measurement and are taking the clearance inside the hydraulic lifter into account. Have you tried following the instructions in the manual to see how close your cams are to the specs in the manual? I would try it a few times to get a good idea of how it should be done before making any changes. Unless someone has already messed with the cam timing, it should be very close to the specs in the manual. You can look at Ferrari workshop manuals of other cars with hydraulic lifters (355, 360, 550) to get an idea of how the procedure is done. Some of them are a little different, but all have to take the play in the lifters into account.
But looking at the procedure, something doesn't seem quite right. It will be interesting to see if you still have zero lift on the intake cam at TDC, and see if it actually starts opening at 7 deg after TDC. With the solid lifter cars, I am used to seeing the intake valve open before TDC and the exhaust close after TDC.
That is interesting. I looked at a 612 WSM and the procedure/cam timing specs are the same as the 575. Basically they want equal lift (1.5mm) on both intake exhaust lifters on either side of 18 degrees after TDC. On a 550, and most other Ferraris, they want equal lift on the cams on either side of TDC. I don't understand why they have the crazy retarded cam specs/timing method. Perhaps someone well versed in 575/612 cam timing will chime in?
Some excellent first hand info here, I have nothing to add as have not got to this stage yet, but it is a thread I will be revisiting when I am, to pick up some tips.
I think that I would check and record the timing of all of the cam events: intake opening and closing, exhaust opening and closing at zero lift and at 1.5 mm lift to get a better idea of where things are now, before you make any changes. Then we might be able to figure out how the procedure in the Ferrari manual is supposed to work.
I have found the ferrari way to be very confusing. Maybe it is the italian to english. When I do this procedure I always make sure that when I finish the "assembly marks" are near perfect. This confirms that I haven't done anything stupid. Steve...how are you finding TDC?
How do you go about finding TDC? There is a dwell period at the top of the stroke where the crankshaft rotates, but the piston remains still. In order to set TDC on your degree wheel (goiniometer), you would rotate the crankshaft until you are 2mm before TDC and note the value on the degree wheel, then rotate to 2mm after TDC and note the value, If you are at TDC, there should be the same amount of degrees on either side of TDC with the piston down 2mm. If not, reset your pointer so that you have the same amount of degrees at 2mm on either side, and now you will be at TDC in the middle.
Brian, I do not want to cause a controversy but I am curious if what RifleDriver says below is true or false? What does Ferrari actually say or are they not officially saying? Is what RifleDriver says official or from a private conversation with a master tech in Italy or something? There are a few degrees of dwell in every motor so it should make a difference just like Ferrari uses the convoluted timing method on the ramps vs. a lobe centerline peak. I mean if we are going to do all this effort we should start from where Ferrari intends..."Ferrari TDC." This is a quote from RifleDriver: <<In every other vehicle or enviornment I have been exposed to TDC is defined and measured as the point halfway between when the piston arrives at its highest position and when the piston leaves its highest position, or the middle of the dwell period. Ferrari defines TDC as the exact point at which the piston arrives at it's highest position when the motor is turned in it's direction of rotation, and depending on a variety of variables those two places can be a couple of degrees different.>> https://www.ferrarichat.com/forum/threads/550-check-engine.34402/page-2#post-134486734
well, I rotate the crank until the dial caliper stops moving, and if I relax my pull sometimes it backs off, so I gently pull some more to get back to the min dial gage reading,. I will try the 2 mm method tomorrow and see if there is a difference from how I do it.
2 mm drop on tdc each side of my tdc was 16 degrees dead nuts intake is 14 ° before TDC to 112 ° after BDC exactly what I think the camshaft numbers call out I need to set up exhaust side now before I can check lift on either side of TDC
FBB, I have not taken the Ferrari class on cam timing. I have always used a piston stop tool with a degree wheel in order to find TDC. I am not surprised that Ferrari has their own way of defining TDC,and am sure that what RifleDriver has said is true. The difference between using the halfway point at TDC and Ferraris method is probably negligable, depending on how you do it (from being dead on as stevepaa found with his car, to maybe 1-1.5 degrees). It's the other crazy method as described in the 575 manual that I have a hard time with. From the cam timing specs that they initially specify to the method of rotating the crank 18 degrees ATDC (2.43mm) and then looking for 1.5mm lift on the cam.
Hmmm, so it looks like the Ferrari cam timing specs are not in crankshaft degrees, and the -7 degrees BTDC is actually not a negative valude?
Yes, the cam numbers are camshaft degrees, and the -7 should be +7 ±1 before TDC meaning14° crankshaft before TDC
set up exhaust opens at 59 ° crankshaft before BDC closes at 66 ° crankshaft after TDC this close to Cribb's 550 data for exhaust I think I would like it to open a few degrees earlier, maybe at 64 ° we just need some correct timing data from someone who has done a 575
Bizarre, I have never seen Ferrari use camshaft degrees for cam timing, only crankshaft degrees. I have yet to time a 575, so it will be an interesting experience. At the dealership, when we do a belt service, we just replace the belts, and make sure that the marks on the cam pulleys line up with the windows in the belt covers. Due to flat rate pay scales, there is not enough time allotted for the service to remove the cam covers and actually check the cam timing.
Image Unavailable, Please Login Steve, You are confusing the heck out of me. Nothing is in camshaft degrees or read off the cam or math done to convert to camshaft degrees. Everything I have ever done is read off the crank with a degree wheel in crankshaft degrees. When I see numbers Ferrari gives they are always in crankshaft degrees as far back as the 1970's when I 1st got into these cars. Your numbers also don't appear to be anywhere close to John's numbers. IMO if you are getting the numbers you got aren't the assembly marks way off? If so that would lend more credence to my statement. I only do this job a few times a year so I have to think about it everytime I do it. Last time was on 550 and I get what the ferrari manual states but it is really not important if you cam time the ferrari way since they never talk about using the timing diagram specs. But using the timing diagram is a nice check to see that things are where they are supposed to be as are using the assembly marks. Here is John's comparo on the 456/550/575. I have not done the 575 so don't understand why john uses the term "corrected" and I don't understand why intake open on the 575 would be 7* instead of -7* as the WSM states.
