308 camshaft alignment question

Hi I have carried out a cam pulley and cam belt replacement. I have spent ages adjusting the new cam pulleys to get the cams to line up with the alignment marks. The left hand pair of camshafts are exactly aligned but the right hand pair are out of alignment by the thickness of the alignment mark, ie pretty close probably 0.5 to 1mm out. Both the right cams are the same amount out. Question, is this as close as you would expect and therefore acceptable or do the marks have to be exactly aligned?

 

I'm sure it will run, but it won't be optimal. You really need to degree the cams to be sure they are in the right position. There are lots of threads about how to do it.

 

On the front of the camshaft pulleys you will see a series of holes drilled into the sprocket These are fixed with 2 HT pins.

Take these out and rotate the cam so the marks line up exactly with those on the cam cover, then replace the pins in the next or best available holes.

They must line up...all of them.

You can use a degree wheel but not worth it in my opinion, the Ferrari alignment marks are pretty accurate even with the normal running shims in situ

Tony

 

Gents,

You might want to read some cam degreeing threads here. Those are just 'assembly marks.' They are NOT 'Tuning Mark's.'

There is some 'less than optimal' advice in this thread.

Please read more as sometimes those marks are 'dead on' and sometimes 'off by a mile.'

 

When you replace worn belts with new belts, the cam pulley teeth may not align with the new belt teeth. That's perfectly normal and is due to belt wear. The slight shifting involved has no impact on the actual timing of the engine. It is normal for some "shifting" of the cams to be required to get the new belt teeth to properly engage if the old belt is worn.

BUT again, this has no impact on the operational cam timing. For example, if you place the cams/crank using a degree wheel to ensure everything is as precisely correct as it can be, you will likely find that the teeth on the pulleys/new cam belt will not align and that a slight shift of the cams is necessary for the belt to drop into position. That's just the normal tolerance for the assembly.

Contrari-wise, if you check the alignment of everything with the old (worn) belt, you will probably find the same thing - the "alignment" is out by a slight amount.

 

I noticed that you have 2v 308. I would not worry too much about cam timing. Just get the timing marks right and you will be good enough.

 

WTF are you talking about. He is changing the timing belts not race preparing the engine. The marks on the cams / flywheel are factory set, if the marks all aligned on dismantling to change the pulley and belts then they must be aligned on re-assembly......

Ever wondered what the vernier scale on those cam sprockets was for!!!

 

The marks get you close and yes, the engine will run without doing a cam degreeing, but if ya want the engine to run really well, the degreeing is needed. It's recommended and in the shop manual.

 

This is what you might end up with "dialed in". This is a 1978 2V motor.
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If you want to, I have helped Ron @ superformance rebuild 12 engines over the years and everytime we have used a degree wheel the factory marks are always spot on. 99 dino engines as well!!

Race preparing the engine using different cams, HC pistons etc etc... then yes

 

Agreed. If it's worth doing, it's worth doing right.

 

I am using new superformance cam pulleys, new tensioner bearings and new belts

 

Tony is right, I heard from one of the Ferrari engine rebuilder said that the assembly marking is about 99% accurate as if you we're to degree it. If this is the case then there,s no need to degree your cam.

 

Tim, Thanx.

Rifledriver has pics of cams equally bad and 'perfectly timed' posted here as well. But one has to run a search to find them. They are years old.

Driving a hand-made Ferrari and employing blind acceptance just doesn't make sense.

 

It makes me nuts that Ferraris need dialing in but it's just how it is with them. The guys that claim the marks are accurate must have seen the only ones that are or have lower standards than me. On the car pictured, only one mark (of four) was correct.

I doubt the timing instructions would be in the manuals if they weren't necessary. Time is money and fiddling with cam timing takes a lot of time that is hard to bill for. It's a lot cheaper to just line'em up and let'er buck.

 

See 2NA's pics above. There are more pics here that look just like that.

I am ass-deep in timing my cams now. Even making a tool to make it easier to do. It is harder than it needs to be.

If one assumes the cams were at factory spec before the belt change, or accepts the setting no matter how close/off they may be, l agree with your assessment it should run as well or poorly 'after' as it did 'before.'

Line the marks up and forget it. It will run like a car; maybe like a Ferrari.

Index the cams, Guarantee it will run like a Ferrari.

 

totally agree. Of all the engines I have helped rebuild, all of them did not need any further adjustment from the factory marks.

There is much more room for error in using the degree wheel. Get the calculations / spec wrong and you screw the whole engine up.

Fine on the bench with heads off but in situ you are asking for a whole heap of trouble unless you triple check your settings.

There is no blind acceptance involved, if the marks all aligned on removal why would they change on re-assembly!!

 

I disagree completely with the "assy mark" comments. I'll explain, I've run more then I can count camshafts thru profile acquisition. I.e. lift per degree while noting the the mark as well. Guess what, that mark is spot on to the specs in the WSM. There is also another bit of information and this is perhaps the most critical and comes down to metallurgy. The camshaft is hardened, so much so that trying to put a 'notch' or 'assy mark' is not going to happen without something going very wrong, either the chisel will shatter or the camshaft will.

 

I doubt the average person would even notice a cam being off 3 or 4 degrees. Those marks are Grand Canyon wide when talking cam degrees.

How far off in cam degrees was the mark in the pic? Do you recall?

 

Nobody said there isn't room for error. This is why everything gets repeated several times. If the marks were lined up on removal, the last job was possibly done by someone in a hurry. Hondas and minivans don't need dialing in.

 

Do you know for certain that it has it been done correctly? its so easy to make an error degree timing the camshafts, it may run poorer than it did before or worse still when the valves hit the pistons.

Unless you are 100% competent in using the DW confidently and have the original stock cam specifications to refer to, then huge errors can be made with dire consequences.

 

112 engines later.

most don't use the correct valve shims?

 

dialed in to what? Not being argumentative here. To me that is a result of 'stacking tolerances' i.e. degree the camshaft timing to the shim gap. That's not what the procedure is in the book.

I've taken the time over the last decade to have an accurate 3d engineering model of the V8 series of Ferrari engines and I'll say I'm impressed with the degree of accuracy and design behind these engines. The pic shown highlights what happens as things wear, the valve seat, valve length, shim gap, bearing gap tolerance.. etc.. Dwell is also less then 1* on the crank. belt stretch and slack, lash between the belts and gears. Thrust on the timing gear in the front cover will over time cause lash wear, this impacts the timing as well.

So by setting the timing to the valve events instead of cam marks will net different results. No surprise, but if it shows to be out far enough then I suspect something is worn out a bit more then should be, when tolerances are out in enough parts they stack up and create the disparity.

I'm not in anyway questioning your methods or knowledge, as you are very well aware the cost of setting things to factory spec on a fair number of these engines is cost prohibitive and could be impossible at it would require replacement of parts that don't exist new. So a balance is struck. I just contend from the engineering side that Ferrari had it spot on if it's setup to the marks and on an engine within spec.

 

I have no idea what you're talking about or how the mark is referenced in the WSM. The alignment (assembly) marks on the older cars are apparently made with a chisel before the cam is hardened and ground. I've seen one cam with two marks (pictured here) that were obviously hand chiseled. Neither mark was spot on.

The car will run, but it won't necessarily be right.

Remember, the camshafts turn at half the speed of the crankshaft. One degree on the cam is two degrees on the crank.
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This is the method described by Ferrari. It is reasonable to assume that camshaft lobe wear will move the timing marks a bit. This supports the argument for using the marks only for initial setup. If only wear was responsible for this inaccuracy one would expect all the marks to "drift" in the same direction as the cams wear. I've noticed both advanced and retarded conditions so that doesn't seem the case.