Cam Timing and its significance on performance

Well now, this is extremely interesting and timely. I've been following the F40 thread and it's been making me nervous.

Two weekends ago I spent ALL DAY Saturday (and I mean all day) and half of Sunday dialling in-the cams on my 355.

The reason it took so long is partly because it's the first time I've ever done this job, and partly because I refused to believe that the timing marks inside the cam-cover could be so perfectly aligned (based on the conventional wisdom on this site).

I double, triple and quadruple checked both cams and both banks and sure enough the timing notches were absolutely spot-on.

Net result of 15 hours work ? NOTHING. I left the cams where they were. I made this decision after talking to a couple of Engineers in my Co. that design camshafts for a living, they basically confirmed what Ferrarifixer wrote, i.e. you couldn't measure on an engine dyno if 1 cam was a degree or two out. All you're doing is moving power and torque curves marginally, but the area below the curve basically stays the same. The only way to make a significant difference is to change the actual shape of the lobe.

Despite all this, I don't feel like I wasted my time and am happy KNOWING it's OK.

For interest, here are some pics I took...

& BTW, I took the measurements with old & new belts for the sake of comparison & it made no difference.

 

My experience mirrors Dave's. Many, many cam timing marks are spot on, some are not. I too have experienced marks over a width or two off from where they should be. But then my sample is only 25 years long. Many US spec cars have a different exhaust cam timing spec of 4 or 5 degrees. If run at the std spec you will get check engine lights and a overheated cat within blocks. With the diameter of the camshaft being what it is do you really believe that you can eyeball the 2 or 3 degree difference it takes for those problems to manifest themselves? I agree you can get away with a lot on cars that don't have the OBD monitoring systems that US cars have but at the same time that does not mean that it makes no difference.

Ferrari does not have an obsession with cam timing in order to make the dealers a greater profit. Frankly Ferrari does not really care about their dealers. Dave and I have learned that after many years of dealing with them. They are obsessed with it because it does make a difference and in this case I have to go with them because I suspect the combined wisdom and experience of that company on the subject of tuning motors beats mine all to hell.

 

From an engineering point of view, I suppose that some of these seen errors are a possibility of an accumulation of errors in manufacturing i.e.: - The grind of the camshaft relative to the holes in the end of camshaft and the holes in the pulley relative to the markings on the pulley. Although I would have thought it would be quite small, accumulative errors can mount up very fast.

We have had to make components in the past that require a peripheral marking that is relative to a radial feature and we usually make a fixture up to drop these items on to. Bearing in mind that there will always be a couple of thou clearance on the pins in a fixture like this, it’s always possible to take the clearance out by twisting one way or another. In the case of the pulleys on the Ferrari engines, I would find it hard to imagine that with decent fixtures an error of more than 1-2 degrees would be possible but it would all depend on the accuracy of the jig that is used to stamp the marking.

(Or maybe how many bottles of Chianti that they guy on the press had at lunchtime! )

Paul

 

The error is in the cam itself. You have to understand it is Ferrari policy that those marks are primarily for assembly, not for timing so they are not always very careful about making them.

In the factory at the engine build department they degree in every cam on every motor. They know the marks are not a good way to do it or they would do it themselves. Also for many but not all Ferrari motors built since about the Testarossa the back of the cam has a mark put on it by the original engine assembler as a true timing mark that has been determined as correct by degreeing in the cams. It is placed there so that in the event that the engine needs an intervention of some nature after testing, the motor can just be reassembled to the hand made marks. Quite accurate if none of the timing components have been changed. Those guys know that the cam marks made during the manufacture of the cams are not to be relied upon. They are under a lot of pressure to keep the units rolling out and if a headgasket for example needs to be changed after the dyno run they dont have time to completely retime the motor.

 

I was just wondering one point..Why in the 360 manuel..does it say to remove the rear most end caps on the camcovers, and use those marks to time the engine by?

Also..I have found that when doing the first time belt service on any newer Ferrari that I have done (348/355/456/550/..when using a dial indicator to find excat TDC I have never found any of the marks to be out of alignment with the marks on the caps...I do check everything with a degree wheel..but I have never had one that is off the mark. Maybe I just haven't done enough of them..but I really can't see Ferrari's manufacutring proccess to allow for that much of a difference..maybe I'm wrong...I could see it on an older engine absolutly..but the newer cars...

 

Further down in the same chapter they show you how to do it with a degree wheel. You also have to know that some of the most important information is what is not in Ferrari manuals.

How would you know if the mark was off by 5 degrees, you can't see it.

Just using 360's as an example Ferrari saw fit to drag Dave's and my butt's over to Maranello for the product training school. It was 4 1/2 days long. Out of that time about 2/3 of one day was spent familarizing us with the then new SD2. About another 1/3 to 1/2 of a day was spent on general topics, new information of various types not specific to the 360. That leaves a little over 3 days for the 360. Almost one full day, somewhere around 25-30% of that time was spent with a motor on a stand doing hands on training of cam timing.

So all you guys can do it any way you want but that is how important cam timing is to Ferrari. And last I heard they had a couple of world championships under their belt.

 

First off let me say I am not a crusader to change anyones mind on this subject!
I have to pack for my trip up to Canada, so I will chime in at length later this week.
Cam timing means everything to a race engine builder. It was stated earlier in this thread that only changing the profile on the lobe will make a differance. That would be the case if it was a single cam, no so with 4 cams that can be set individually. Lobe seperation between the exhaust and intake cams will make a substancial differance in performance. The key is to set the cam timing to each individuals driving habbits. Yes to some degree it is moving the power curve from here to there. How many have tried to see if the entire cam profile is as stated in the Ferrari manual? I have yet to find one that meets the specs, and here in is the "consumer acceptable" level of quality.
The Factory race cars are a differant story. The old TdF, SWB and GTO that Dr. Bodin used to own and race had a whole story to go with the cams. For each track they were raced, there was differant cam setting. Francios Sicard shared with me pages of cam settings for these cars, as it was my job to keep these cars glued together. Bob had boxes of GTO cams that I put in the lathe and degreed each of them to find out what the duration and lift each of them had. These were origional cams from back when consumer acceptable was not a know term at Ferrari, and yet were quite differant one to another.
There is a whole story about Brian and my experiance at the factory regarding cam timing. After we sat in that class on cam timing (maybe it was before, I do not remember), we toured the assembly line and watched the timing being set BEFORE the cams were stamped at the ends. Short version of the story, we called the trainer back and had the engine I watched being timed, rechecked. This is one engine that now has multiple stamps on the cams! The factory method of finding TDC is turn the engine over until the dial gauge hits the highest point, goes past, then turn the engine back to high point. There is NO 1MM before and after drop, no positive stop method used, nothing! More on this later when I have my laptop with.
One would have to do back to back pre delivery drives to know that 20% of the new cars were DOGS, 60% were good runners and 20% were rockets! Cam timing is the differance between most of these.
There is a customer / friend that I did many thousand miles of track time with in a 360. This was a 99 and when the miles racked up he got another car to replace the first. The new car was a 02 if I remember correctly and fell well short, seat of the pants, to the performance of the 99. Our tech rep from FNA was a friend of his and under warranty authorised me to find out why. First was the cats in the headers were a good bit of restriction on the later car. The rep made us do dyno runs between any changes. Cam timing the engine in the car added a substancial benifit. I will try to see if I still have the dyno sheets so it isnt just a putz saying this. I also have a CD with the pics of the 355 I wrote about earlier regarding the marks being off. As Brian said, it is not all the time that the marks are off, but some of the time is bad enough to justify degreeing the cams all of the time.
Dave

 

If you're referring to MY 355CH...and remember, I have no idea what I'm talking about, the dealer told me that he set the cam timing to something other than "standard" as this setting was found to be better by people who race those cars. Different isn't necessarily incorrectly, but whether or not it's true or if it had any negative or positive difference I'm not able to say. Certainly, if you are talking about my car, and you've changed the timing from what it was, I definitely can't feel any difference.

 

Good point....might be timely to have a dyno run on the car, AHG

 

Like Dave said, I'm not on a campaign here either. All I am relating here is Ferrari's unambiguous position on timing of cams and my experiences with same. Frankly it does not matter to me if you degree cams, replace timing belts, adjust valves or even change motor oil, all I can say is that Dave and I and quite a few other people we know are making a fair bit of money sorting out cars that have been serviced by another standard.

 

You are far from a putz Dave.

 

Guys, what's going on ?

This seems to be a case of "violent agreement"
1. Everybody agrees that CHECKING the cam timing with a DTI is a good thing.
2. Some people believe the majority of cam-side marks are accurate (at least on the newer engines).
3. Some people believe the timing marks are a coarse guide only, not to be trusted.

Points 2 & 3 are taken care of by point 1.

For sure, many "so-called" specialists lock-up the cam pulleys and just change the belt like-for-like. And just take the money.

You guys have my total respect for your knowledge and experience. If I didn't roll-my-own I would bring my car to any of you guys.

Although my marks were spot-on, I'm glad I did the check and would do it again.

Can we get back to talking the importance of cam timing and forget who-does-what ? I'm really interested to get some data on the table. If we weren't scattered all-over the planet I'd invite you all around for a beer & you could laugh at my pathetic garage.

In the meantime, I'm off to paint my subframe...

Rob.

 

Oh...well you already know what I think of his workmanship. That doesn't change the fact that I could feel no difference, so I wonder what difference it REALLY makes, or if it would be something that only a dyno would pick up, and a mere few HP.

I guess you'll have your chance to undo all your good work again next week and return the car to it's previously shonky state, hey?

 

From the engineering standpoint, this is cool stuff to ponder. I believe that back in the day when the Offenhauser pretty much ruled big-time American open-wheel racing (mostly on dirt tracks), mechanics were known to advance or retard the timing of the intake cam to compensate for track conditions. Advancing would give more grunt down low, and when the tracks got slick, retarding the intake would apparently raise the usable torque band somewhat. Anyone else familiar with this???

 

Well, you may have a point there Phil.

In October 2003 at Sandown my best time was 1.25.96.
I had a major service in October 2004, including new spark plugs etc, noticed I had lost my "waah", put Michelin Pilot Sport Cups on and went back to Sandown the following week, expecting to better my previous best time.
I was slower by over 2 secs which is a lot...1.28.22.

I thought it must have been the tyres which I did not like or my driving!!!

The car did feel flat, and my nephew who also drive my car said the same thing to me.

What should I do next?

Regards,

AHG

PS: I did a 1.26.23 in my Standard E46 SMG M3 in August 2004, so I believe I should be achieving 25's in my 355 F1.

PPS: My test day at Winton last month also yielded somewhat disappointing times, 1.40...could only get under 1.40 with Aircon's Hoosiers.