Jumped 1 tooth on intake and 2 on exhaust?

At this point you should just put it at TDC #1 and see where all the marks are.

Keep it simple for now.

 

I don't really know the answer to your question but when the rear bank on my engine had a castastrophic breakdown it was only the intake valves which had contacted the pistons. I believe therefore that my belt jumped only on the intake cam pulley and the exhaust cam was still timed properly or at least not enough "out" to cause contact. I concluded that in my case the intake cam experienced some seizure or near seizure incident which caused the belt to skip on that cam pulley and then re-engage out of position thereby causing me to have a very bad day.

BTW my issue was not a loosely tensioned belt. It was under proper tension.

 

RD is telling you to start with basics i.e. the relative assembly marks at TDC. It is also possible that everything is close to correct for old stretched belts because assembly marks do not always equal the proper degree wheeled/dial gaged timing. Also, many cars have been set to assembly markings with belt change being done with cam lock tools, nail polish marks, and pinned cam cogs...so... there is error built in right there which can explain being off. You do not need a shim removal tool. In fact using one IMO is harder than removing the cams.

 

I'm going to disagree that the marks are important now. Since you have the cam covers off, who cares what the marks on the cam wheels say. You're on TDC, degree the cams, remove the cam wheels and set it up by the WSM. Then, rotate it around carefully by hand, check your clearances and if you need to reshim you can check the degree setting again.

I found two of my cams set one tooth off when I bought my car. I think it had to do with a shop doing a quick belt job maybe and let the cam slip, so they just moved the cam wheel so the ticks lined up, but didn't bother to check the cams by degree.

Just a note on how I do it. Once I get the cams in perfect degree setting setting, I take off the cam journal cap near the front of the engine, and use a piece of matchbook cover cardboard(thin) then put the cap back on and lock it in place. Don't need much torque on the cap, it just holds the cam in place while you line up the cam wheels, belt and crank then tighten everything down and set the belt tension. Once that's done, don't move the engine! Take the matchbook out from under the cam journal caps and put the cap back on with a touch of oil. You can rotate the engine now and recheck the degree. Lather, rinse repeat for the other bank.

 

Use a good quality dial indicator to set TDC and your assembly marks should tell you, in a farts time, if you skipped a tooth. Your numbers are way outa wack therefore I kinda don't trust your positive stop method. Belt slack will throw things off if it is not set up properly and rotated in the right direction. The engine should only be rotated in clockwise direction when you are doing this and make sure your dial guage on the shim bucket is parralel to its movement.

 

If the marks line up (even close) the belt didn't jump.

Don't outsmart yourself.

 

Tim (2NA) is right. I am another person worried about a jumped tooth (or two) and will be checking the marks soon. However, remember that the teeth are 12 degrees apart. If the marks are close but not perfectly aligned, you did not jump a tooth. 12 degrees is a long ways around that circumference.

 

Exactly.

Don't make it complicated.

Put it at TDC and look at the marks.

It ain't rocket science and the more complex you make it the more probable someone will screw it up.

 

Mark,

One alternative method that you might consider is degreeing of the maximum opening point of the cam, rather than start and finish. Several guys I know use this method and say it is completely dependable. The maximum opening point is easy to determine, and it should occur at the mid-point between the theoretical start and finish points on the model degree wheel. The maximum opening point is not dependent on the proper shimming to .050 per the manual. No matter how it is shimmed, the top is always the top.

I know it is unorthodox, and I'm putting on my flame suit as I'm sure others will flip out at the idea, but I've seen it done and helped do it, and it seems to work just fine. Plus, it saves the work of re-shimming the cams just to degree them, and then re-shimming them to set the proper lash. Instead, you set the lash, degree the cams, and you are good to go.

Steve

 

I completely disagree! It's totally sensible to use as many events as possible (opening plus a small amount, max minus a small amount, max, max minus the same small amount on the other side, closing plus a small amount) as a way to check your work (and as a way to make sure that the cam lobe matches the setting data that you are using). In the extreme, the complete profile of all the lobes should be measured and then "best-fit" onto the ideal profiles -- there's no gaurantee the cam itself is "perfect" (although their error is usually small).

 

I never change shims and time by in open and ex close times. It is simple to the extreme.

You are advocating timing at max lift. When is max lift? The information is not published. Most erroneously assume it is at the midway point between open and close times. Bad assumption because many are not. Good way to screw up something simple.

Ferrari designed and built the motors. They time them at the factory the same way they tell us to do it in the book, I have watched them. The goal most of us are trying for is to make the motor run the way they intended. If that is the goal there is no reason not to do it their way. If on the other hand someone is trying to improve on that and they have the knowledge, experience and resources to do that there are other methods that work well but those people do not need us to tell them how to do that.

 

Point well taken, Brian. The way it was explained to me, the cams we are working with are symetrically cut, that is, the ramps on both side of dead top are the same, going up and down, and the dead top is right in the middle. So full open, would indeed be midway between start and end of the cycle for that lobe. As Steve M pointed out, finding that point is pretty easy.

But, I do get your point about making sure that the car is set up as close as possible to the way it was intended to be from the factory. To be clear, I was not advocating that it was the way to go, just pointing out that it is an alternative method. And as Steve M mentioned, it can also be used as a way of checking your work as well.

 

Ferrari cams are not all ground that way.

 

I'm not that smart but you can calculate "installed centerline" which is max lift so the math will be correct and give you max lift so you don't have to guess at it with a dial gage. Here is a math example:

http://ferrarichat.com/forum/showpost.php?p=136687450&postcount=2

Both methods of cam timing work and there is no guesswork. The installed centerline method only works when the lobes are symetrical as you posted. On the 348 and the 550 they appear to be symetrical as my numbers match when using the centerline method or the opening method. Everyone knows how to do this on a chevy motor with 0.050 opening and reading a cam card etc... On ferraris often times I have to try and figure out interpretations of the specs. as I illuded to in the above antique post with my dinking around with what valve lash made the numbers work. To you they are crystal clear having gone to Ferrari school to fill in the blanks. For me reading the WSM in engltalian is like trying to find my a$$ with both hands.

 

FBB you are wrong. GET OVER IT.




There are many Ferrari cams where the max lift does not happen at lobe center.