A. Yes if it was increasing the overlap. B. Different models react to different levels. Generally the more highly tuned the more they react. 2V 308 you couldn't tell. A 355 would be noticeable to a very astute driver. You couldn't tune it well. C. I have never tested for that but I doubt 10 degrees would crash valves in any Ferrari with stock pistons. Some of the old 250's and 275 comp motors had tall enough pistons and steep enough ramps 10 degrees could do it. D. Depends on driver and model of car but is detectable during tuning on a 4 or 5 valve down to 3 degres, maybe 2.
Some of the 250 and 330 race engine I have built run 2.5 MM valve to piston clearance on the exhaust side with race cams... throw in chain stretch and valve float and things get intimate quickly. There was one Cat eating TR in town here that the owner refused to have the belts done on. When the engine finally came out (3 Cats and 11 yrs or some fool number like that).... 4 degrees on one exhaust cam. The folks that warrantied those Cats were not too inclined to give deals on that major. Brians photo's should end all debate on this issue!
Hehehehe.....the pro stock engines I used to build, we'd set up piston to valve clearance at .020" on the intakes and around .060" on the exhaust. But we also had 1300 lbs open pressure on the springs! As long as the driver wasn't a total DSPO, we never had a problem except for springs getting killed every run.
Well, if you've never done this before, my suggestion would be to find someone near you who has experience doing this, and have them work with you. It involves locking the cams, removing the cam gears, and re-aligning the pins that lock the cam gears. This must be done the right way, and cam gear bolts torqued properly, etc. or you have big problems. Also, setting the cam gears properly can be a time-consuming trial and error process to get the pin combinations correct to get the timing spot-on, so you need to be prepared with plenty of patience. I'm sure the pros know the shortcuts and how to set them up more quickly, but we amateurs can't rely on years of experience that we don't have. Look at the shop manual for your car, and if you are not 100% sure of what you are doing, my recommendation is DON'T do it. Either get experienced help or take the car to a qualified mechanic and have it done right. The risks associated with doing it wrong are just too great. YMMV, but that's my $.02.
You detorque the bolt at the front of the cam, and remove. You find the pin holding the pulley in synch with the cam and pull it out You then move the cam to the correct timing measurement with a dial indicator with engine at indicated TDC (correct measurement if found in WSM) You then reassemble the belts and pulley and find a hole where the pin will fit You then torque the cam bolt back in place. (*) it may take a couple of tries to get the pully and cam in such an orrentation where the pin fits perfectly.
Nice avatar, Herr Goebbels!! BTW- here is one of my favorite quotes from Joseph Goebbels...it fits right in here alot of times, huh?: "If you tell a lie big enough and keep repeating it, people will eventually come to believe it."
I Understand that is it risky to attempt working on your own car. But I enjoy it, and willing to take the time to learn, and accept the risks. I guess one more story tell to the grand kids. I don't plan to know everything when attempting this, but I will figure it out.
"most" late model, 4-vale engines(injected as a whole...?), have rewference/"roughing in' marks as mentioned earluier. Principale perpose is-as stated-is to keep collisions during final "dialing in"/degree timing.. Carg and CIS cars are are slight oxymoron.."where the intake valve opens and the exhaust valve closes," as oppossed to when the "intake closes and the exhaust opens"...an opnion argued by many... ...none the less... the factory, typically, sets a chisel mark AT THE REAR END OF THE HEAD/LAST CAM CAP AND THE CAMSHAFT upon FINAL cam timing, While these are NOT to be regarded as "god" references, usually, they are to be found to be far more accurate than the ones found at the "FRONT OF THE HEAD/1ST CAM CAP" The vernier holes found on the front of dinp/daytona/P6 cam sprockets have an adjustment of 1.5 degrees /hole for adjustment...within a degree "or so" is FINE... even build sheets typically show that the second set is advanced a degree early to compoensate for chain stretch and so forth...the criticality of a clearance shim exactly at .050 is/cannot be stressed as to importance with respect to accuracy of timing... Racing piston manufacturers will typically call out a clearance of .100 min clearance between valve and [pistons...race cars will do to .050", and really recision, money is npo object can and do get as close as .020-.030"..btu that is, as I said, where time, money, and resources are limitless and winning is all that matters... Not much of a safety net at those clearances.
Well, good luck, and let us know how it goes. Again, IMHO, this ain't the place to be experimenting and learning from your mistakes. Be darn sure that you have the engine at exactly TDC on the intake stroke of #1. If your cams move on you when you are doing this (which happened to me), you will need to get them back where you started from. Noting the position of the reference marks on the cam and cap (digital pics come in very handy here) can help you get back to your starting point, if needed. Again, this is just me, YMMV, but I would not start this process if you've never done it before and without someone who has done it helping out. It is just too easy to screw things up. I'm not afraid to tackle most projects, but Murphy's Law will come into play when you do this one, and having an experienced person with you can make all the difference between getting it done or having it towed to a mechanic to bail you out. Again, that's just my $.02. p.s. When you degree the cams, make absolutely sure that you are using the correct timing specs for your car. They differ between US and Euro, 2V and 4V, carb and injected. If you use the wrong set of specs, you're toast.
On working with the 'pro-wheel' I think, once its set on the engine, you really shouldn't touch the degree wheel because it could easily be 'off'. To set the wheel, I used the method as described earlier, which is the piston-stop way. Further, a measurement should be done twice and in 1 go. This means no coffee or telephone! Good luck.
One other thing. About the markings on the camshaft. With all comments made on the subject one could argue those factory workers were drunk when putting them on. You know the Egyptian builders from ancient time commented this way on fellow workers. And guess what, the pyramids are still there and this Ferrari engine probably ran many miles! I would say put those timing belts on and have a couple of beers in the cooler?
True and I have seen Ferrari motors coming out of the factory missing head nuts, having loose cam caps and missing wrist pin clips. Sorry but something about me, I just can't perpetuate the factory F-ups.
I almost regret to post this for the backlash but... I have had 6000+ miles of blissful and carefree driving since setting the cams on the factory marks. Emissions not an issue where I live. Carb car if that could matter? In all likelihood I have the stock cam sprocket (gasp). And, then most likely I also have sodium filled valves (double gasp). Perhaps blissful ignorance, although now better informed as a result of this thread. Am I in the wrong? Is so, how should I make amends?
Everyone has different standards. Combine that with the fact that most have no idea how good their car can be when it runs right. Did a major service on a 275 4cam a number of years ago. The guy had owned it for 20 or more years. The guy came back a week later ecstatic because his car had never run that well. He drove it 20 years without knowing how good it could run. What is the point in having a Ferrari that runs half assed?
My 348 had a clutch shaft lockring not staked by the factory. It failed of course and FNA could care less.
