I have a few questions about removing a 328 cylinder head. It would be great if you could help me on any of these ! 1- I have no signs of wear on the camshaft bearings. Should I (or do I need to) ream them after I put the head back in place? Can the procedure of removing and refitting make any difference? Since it has to be done with the head in place, and the engine is in the car, this could be a problem .... 2 - the WSM mentions on page B-37 the correct tightening order for the head nuts. What they don't mention is the order for the four central nuts. Should they be removed before or after the ones under the cams? 3 - On the same page it is mentioned that you should first torque to 4,5Kgm and then use the goniometer to turn each nut 120º. I understand that, but does it apply to all nuts including the central ones? The reason I ask is that on page B-39 they state "tighten cylinder heads to the prescribed torque(see pageM4). On page M4 the torque value is 10Kgm .... What am I missing ? 4 - Where do you buy the cam shims? I need to set the gap to 0,5mm to dial the cams so I need an assortement of shims, and I'm sure there is a cheaper place than from Ferrari or the usual suspects! Remember this is a 328, not a 308 Thanks, Rui
Ok, I have an answer for #2. Those bolts in the center of the head are not head nuts. They are not used to hold the head to the block, they are plugs. Anyone care to answer the others?
Rul- I think you have a misconception on degreeing the cams. The valve clearances are set to correct specifications for degreeing and the measurements are made at 0.5 mm of camshaft lift, not clearance. You use a dial gauge to measure the lift by setting the dial gauge to zero when the camshaft is not lifting (depressing) the valve and then rotating the camshaft or engine until 0.5mm lift is reached. The reason for this is there is a wide zone of camshaft rotation where the lift is zero, and you need a specific, unique rotation point to fix the timing of the camshaft. One of you pros chime in if I have this wrong. Taz Terry Phillips
wrong, they wanted to get away from the transition point of heal to lobe and take a reading up on the ramp where one degree of crank rotation will make a difference on valve opening amounts.
Dave- I thought that was what I said, but what the heck. Guess I did not explain it very well. Should have said there is a wide zone of camshaft rotation where there is no or little difference in valve lift. Your explanation is definitely clearer. Rui- Here is a source for valve shims. From what I see, all the QV engines used the same shims. http://www.newcoproducts.com/ferrari/valve-adjustment-shim-pack.htm Taz Terry Phillips
I have checked the Workshop manual again. On page B42 it says "Bring the valve clearances of cylinders #1 and #5 to 0,50mm. Using a comparator with tracer point on the plate accurately note the opening and closing instants of the valves" On page B51 it says "Opening points of inlet valves and (AA) and exhaust valve closes (CS) are marked on the flywheel to facilitate checks on timing (valve clearance 0,5mm) with the engine installed on the car" You do need to bring clearances, not lift, to 0,50mm and note the opening and closing points with that clearance
Rul- The "valve clearance" they are talking about is the clearance between the valve and the valve seat, which is lift. What Dave was talking about was the "valve clearance" or lift had to be high enough to get the cam off the flattened bottom of the lobe and up on side of the lobe where a more accurate reading could be taken. If you look in your workshop manual (yes, I have it, too), you will notice the clearance between the cam lobe and the valve shim is called "operating clearance" in at least two locations. "Operating clearance" between cam lobes and valve shims is used to provide the correct "valve clearances". "Valve clearance" is the distance between the valve and the valve seat, also called valve lift. To get perfect results, your intake valves should all be at the correct "operating clearance" of 0.20 mm and the exhausts at 0.30 mm. I am too lazy to calculate the difference in timing between 0.20 mm and 0.25 mm and between 0.30 mm and 0.35 mm "operating clearances", so have no idea how big an effect 0.05 mm makes. There is no way Ferrari was going to put in shims to give 0.50 mm "operating clearance" and then have to change out all the shims to get correct "operating clearances" after timing the camshafts. Read FBB's explanation of degreeing camshafts and the resultant Q&A and you will understand all. I think it will save you some money on a bunch of shims and keep you from timing your camshafts incorrectly. Your English is really excellent, by the way. Very fluent compared to my poor German. http://www.ferrarichat.com/forum/showthread.php?t=148917&highlight=degreeing+camshafts Taz Terry Phillips
Terry, for timing purposes the factory method is to set the clearance at .5mm, not lift. You are misinterpreting the manuals instructions. RGiante is correct.
You don't have too (although nothing wrong with doing that) -- any of these methods uses the exact same point (in theory) on the cam lobe "up on the ramp" that Dave mentioned: 1. Set the operating clearance to 0.5 mm (using the thinner shim than normal) -- the "event" occurs when motion at the bucket is first detected. 2. With the clearance at the normal operating clearance, measure this value "X" -- the "event" occurs when the bucket is deflected a distance of (0.5mm-X). 3. Set the operating clearance to 0 (using a shim thicker than normal) -- the "event" occurs when the bucket is deflected by 0.5 mm. As you can see, the trick is redefining when the "event" occurs so that you are at the exact same point on the cam lobe (regardless of what the actual clearance is).
Rul- You were right as the three pros have stated. Should not comment on things I have not actually done myself. Will learn one of these days. Taz Terry Phillips
That makes total sense to me! I particularly liked #2: if you have a 0,20mm clearance, check for the point at which you have a 0,30mm deflection. Save the need for a few more shims and the time to replace them but still do it right. Thanks Steve !
Thank you Rifledriver, davehelms and Steve Magnusson for clarifying things ! Don't worry Terry. I've only seen it done once on a 308 (using the 0,5mm clearance) and will do it myself on my 328 in a few days. It's great that we can all learn how to properly maintain our cars, and that includes me ! Thanks! I know about three works in German ... and one of them is Schumacher ! The only question remaining is how do you torque the heads? Do you use the manual procedure or do you torque them to 10Kgm? A friend suggested going step by step, like 4,5 - 6,5 - 10 ?
The only downside to describing it as it is in #2 is that it really takes a lot more subtle words (and their understanding) so it doesn't work as well as #1 when going thru a language translation nor when trying to write down a specific procedure -- using the #1 description does have less chance of confusion in both understanding and execution IMO so I can't fault them for using it. #1 can also work better with a "poor" mounting arrangement for the deflection measuring device (e.g., the dial indicator) since with #1 you are only trying to detect any initial motion; whereas, with #2 and #3, you are relying on actually having an accurate measurement of the deflection (i.e., if the mounting stand flexes = introduces error). They are really just three descriptions of the same general rule: At the given clearance, the "event" occurs when the shim/bucket deflection = (0.5mm - clearance) Of course, you need a couple of probably "difficult" paragraphs before that to try to explain the meaning of "event", so let's be glad they used #1
I don't know about Ferrari but when I worked on Fords, the torque process was to start at the center of the head and torque the bolts in increments, working your way to the outer ends. This way the head lays down flat and does not "cup" in the center. The step by step your friend suggested looks okay to me.
Can you give your reference to using the goniometer method again. I've got a copy of the 308QV/328 WSM 550/89, and it's got the tightening order shown on page B37, but I can't see anything about using the "angle" tightening method? Is yours a different print number reference?
I havnt yet bothered to sit down and inspect a whole cam (though I will probably check one just to satisfy myself), but when I was young (100 years ago), I recall a few wrenches telling how most domestic cams had lobes all over the place, that it wasnt unknown to find 20 degree discrepencies from + to - of spec (which is why good wrenches used degree wheels and tried to set for the average). And I recall hearing Ferrari were no better. Of course that was in the early 70's before I could drive, and probably refered to the earlier vintage 250 V-12 era when the cams were made out of recycled coat hangers. Or maybe it was those crotchety Chevy guys who have to dumb everything down to their level Have you seen any of this in Ferrari cams, anything worth watching for or worrying about? Or are they pretty accurate, and we can spend our time doing more usefull things like polishing cannon balls? IOW would it be wise to go through all 16 lobes and plot them all, or a waste of time? As to the emphasis to checking timing at .5 mm (.020"), would there be something I would miss if I were to watch for dial indication by subtracting valve clearance? IOW, do we need to physically set clearance to .020", or can we subtract the known clearance (.008" for example) from .020", and start measuring from .012"? Obviously I see the potential for a gross error if your math is wrong, backwards or whatever, and that would certainly be a good enough reason to use the testing clearance. But in my mind I see no difference as long as your careful, is there something I am not seeing here?
