| Author | Message | ||
| Ben Lobenstein 90 TR (Benjet)
Intermediate Member Username: Benjet Post Number: 1189 Registered: 1-2001 |
The only thing I can throw in the mix at this point to help you is: >Open Spec. 16 deg. BTDC / Actual 14 BTDC Many WSMs have the EURO (Cat less) timing settings listed which IIRC are 16deg BTDC +/-1 degree. Very few WSMs list the USA Spec which again IIRC 13deg BTDC +/-1 degree. When we did mine, the tech KNEW that 16 wasn't right, but was scratching his head to recall the exact number - so he consulted the shop foreman and sure enough his WSM was different. My USA WSM has the Euro number (misprinted). So 14 is fine. (from my failing memory) - JRV, FerrariFixer, FerrariDR, anyone confirm? -Ben P.S. If the timing is to advanced you get fuel dumping out the exhuast and cats catch fire  | ||
| Jeff Green (Carguy)
Member Username: Carguy Post Number: 493 Registered: 10-2002 |
LOL....AND LOL AGAIN ! Yep...I think Tom Bakowsky has it figured out! Thanks for presenting the lighter side of this procedure Tom. This story sure has lots of twists and turns doesn't it. I will resort to the factory method as soon as my shims arrive. Till then let's all take a breather. There is one positive thing in all this, and that is I've learned a lot about TRs. As frustrated as it can get, I still don't regret it for a minute. Where else can one get an education in TR service for little money but lots of time? The way I see it I'll have a leg up on other owners who are still intimidated or view working of Ferraris as a mysterious craft. I think it is a craft, but based on learning from others, doing it yourself, and thinking things out when your in a tough spot. After this service I don't believe I would have very many problems doing it again. And this may help me to bargain for a better price on my next TR. I'll know EXACTLY what to look for, little clues and signs that mean the work was actually done or not. So no matter what, I am not disappointed, but lucky to be doing what I am. | ||
| Tom Bakowsky (Tbakowsky)
Member Username: Tbakowsky Post Number: 556 Registered: 9-2002 |
you guys are nuts!! :o) | ||
| Bill Sebestyen (Bill308)
Member Username: Bill308 Post Number: 524 Registered: 5-2001 |
Thanks Phil. I agree contact lines will vary between cylinders. For a "simple" cam timing, one is only dealing with one lobe on a cam and the balance of the remaining lobes are ignored. If one were to really search for perfection, each lobe would be independenly evaluated and any lobe registratiion problems would be either corrected by regrinding or some type of average reading would be applied to the number 1 and 7 cylinder cam lobes (for a 12-cylinder engine). | ||
| Phil Hughes (Ferrarifixer)
Junior Member Username: Ferrarifixer Post Number: 132 Registered: 7-2003 |
Jeff In your own words..."very close" is what you are. But if it's perfection you want....follow the manual to the letter. My view is that perfection is impossible, and you'll send yourself crazy trying to get there. Are you keeping a log of you man hours too, by the way. I'd love to see the bill for this one!! And Bill, no disrespect taken either way, but the assumption simply does not work. The information is based on all new parts with perfect 0.50mm. As the cam/shims wear, even microscopically, the initial point of contact varies greatly between cylinders. | ||
| Bill Sebestyen (Bill308)
Member Username: Bill308 Post Number: 521 Registered: 5-2001 |
Phil, With all due respect, if I understand Jeff's methodology, he is measuring his timing in a slightly different but fully equivalent way to actually having a 0.5 mm clearance. IMHO, the following timing cases are equivalent: 1. A clearance of 0.5 mm: timing event begins at cam-to-shim contact (threshold of first lifter movement) and ends at the moment of seating or loss of contact after rotation. 2. A clearance of 0.0 mm: timing event begins at a measured lift of 0.5 mm and ends when the measured lift reaches 0.5 mm after rotation. 3. A clearance of 0.1 mm: timing event begins at a measured lift of 0.4 mm and ends when the measured lift reaches 0.4 mm after rotation. 4. A clearance of x: timing event begins at a measured lift of 0.5-x mm, where 0<X<0.5 mm, and ends when the measured lift reaches 0.5-x mm after rotation. In all cases, the contact line of the cam and shim will be exactly the same at the beginning of the timing event and at the end of the timing event. All cases will yield exactly the same timing. All cases will work on any cam profile subject to a 0.5 mm timing clearance. Measurements of lift and clearance are equivalent provided they are perfomed with equal precision. The caveat remains for cases 2-4, the dial indicator axis must be parallel to the lifter axis and the dial indicator and mount must be solid. A restriction for case 4, clearance (x) my not be more than 0.5 mm nor less than 0.0 mm. The one advantage to case 1 is that you do not have to measure lift, but you do have to detect contact or the threshold of lift. This may be more nebulous than reading a lift value on the dial indicator. The advantage of cases 2-4 are that one can use the existing clearance and avoid the labor and parts needed to establish the 0.5 mm clearance. How many shims does the DIY'er have on hand to establish the timing clearance with precision? Shims are available in 0.05 mm marked increments so that means if the shim is correctly marked 3.00 mm (not all shims are marked correctly - ask me how I know) it can be anywhere between 2.975 and 3.025 mm. I personally have about 50-shims in storage from my valve clearance project of 3-years ago. It may take 10 shims marked 3.00 to obtain one falling into the 3.99-4.01 mm range. I measured all 50-60 shims with a quality Starette micrometer in 4-locations (not all shims are perfectly flat either) and averaged and recorded each one of them for future use. If you need 0ne 3.00 mm shim, how many are you going to order? In the end, results are often determined by one's skill with a feeler gage which I find to be more of an art and skill than a science. All cases require an accurate determination of the initial clearance. So why doesn't Ferrari specify a method consistent with cases 2-4? I don't know. Certainly the case 1 method doesn't require fitment of a dial indicator which is fragile and time consuming to set up properly. Perhaps Ferrari finds it easer to use a 0.5 mm clearance in a production or service environment where they have lots of shims to play with and presumably are quite adept at changing them? Maybe they want to keep you dependent on a dealer with a quantiy of shims on hand? Perhaps they really don't want to teach more than one method, even if they are equivalent. | ||
| Jeff Green (Carguy)
Member Username: Carguy Post Number: 490 Registered: 10-2002 |
Thanks Phil for your valuable advice. I "think" I understand what you mean about getting the 0.5 clearance prior to checking opening and closing events. But cannot the same measurement be duplicated by measuring the actual clearance, and then "plug in" the difference required to get to 0.5? My Intake clearance was 0.2mm, and I added in 0.3mm on the dial indicator to get a total of 0.5mm. So no valve movement readings were taking below this threshold. I can sorta visualize what you mean about the vagueness of the ramps and such. But I'm still not clear on why having actual clearance of 0.5 and a "compensated for" clearance duplicating 0.5 will not produce readings very close to each other. I may be wrong, but need to understand. Is there a difference of contact points between the cam & valve, using actual 0.5 versus calculated 0.5? They both share the same base point of measure, between cam and shim bucket. Either way, I guess I'd better order some shims right away, just to take things another step. I hope the rest of you TR guys out there are taking notes on this!!!! | ||
| Phil Hughes (Ferrarifixer)
Junior Member Username: Ferrarifixer Post Number: 130 Registered: 7-2003 |
Hi again Jeff I repeat...you CANNOT guess or measure the supposed timings if the clearance is not set EXACTLY to the 0.5mm gap. You are using an entirely different section of the camshaft to open your valve as with a larger gap it opens further/later into the opening ramp cycle, and closes earlier from a different part of the closing ramp. I was worried you would get in a knot over this, so please take a few deep breaths, kick the trash can/dog/garage door and start again! Remember, even when you've got No.1 and 7 doing what you require....just for self torture.....go and check a couple of other cylinders to see if they're the same.... The difference or revision I mentioned is to do with valve clearances, especially exhaust. I think there are two different recommendations, but can't remember if it's between different year Testaross"i", 512TR or 512M Further to my full clearance check recommendation, the way I do it, is to measure all clearances, then remove all the cams and simply pluck out the shims and do my calculations and changes with cams removed, then refit new cam seals and housing o rings, refit the cams and hey presto! The tricky bit is that when you remove the exhaust cams, the buckets try to fall out, so some rubber bands stretched betwen the various studs stops this.... | ||
| Bill Sebestyen (Bill308)
Member Username: Bill308 Post Number: 518 Registered: 5-2001 |
Jeff, I think the measurements you present validate your refined measurement procedure. Could you post a picture of your indicator setup? Do the cam-to-cam bearing cap lines match up as they are timed? Judging by your numbers, it looks like you are about 4-degrees retarded on the intake cam and about 1-degree retarded on the exhaust cam. The difference in duration on the intake cam numbers you measured may be because you are a little tight on your measured shim to cam clearance. Probably on the order of 0.002 inches. I have found 0.001 is about the limit of accuracy when making these measurements. The exhaust clearance appears to be nearly spot on but again maybe 0.001 inch tight. A tight clearance will show more duration when open. I would adjust the intake and leave the exhaust as close enough. As the cam belt streches, the cams will tend to retard. | ||
| Jeff Green (Carguy)
Member Username: Carguy Post Number: 489 Registered: 10-2002 |
To eliminate as many variables as possible I made a plate that bolts to the head, for mounting the dial indicator. Doing this also eliminated the necessity for two adjustable rods for orienting the dial indicator, and now I only need one. This is much more stable. Next I needed to make an offset indicator point. Using a stiff piece of wire shaped to set against the shim/bucket, I then threaded it to the indicator. The results this time were more consistent than previous hair-pulling times. But still do not fall spot-on to the manual. Here is what I show: -- Intake -- Open Spec. 16 deg. BTDC / Actual 14 BTDC Close Spec. 48 deg. ABDC / Actual 54 ABDC -- Exhaust -- Open Spec. 54 deg. BBDC / Actual 54 deg. BBDC Close Spec. 10 deg. ATDC / Actual 7 deg. ATDC As for the magical 0.5mm clearance I simply measured the actual clearance and adjusted the indicator to compensate, and took readings when 0.5mm was reached. I repeated this procedure for each cam 3 times, and each time I was within 1 degree of the first readings. In my opinion I believe this is good enough and no adjustment is necessary. Although I cannot explain the late closing event of the intake. Ferrarifixer Phil said there may have been a specification change to the cams at some point, does anyone know what this could be? Lastly, I do want to THANK EVERYONE who has given advice and encouragement through this procedure. The respect I have for those knoweledgeable mechanics out there keeps growing each time I have to work on my car. |