Freinds, I bought a piston stop to double check my dial gauge procedure. I was a little concerned as I did not want to bang up my piston! After completing the piston stop method, it seemed to confirm my other measurements. I wanted to double check as many said the flywheel mark should be off so I was surprised that it was spot on. 1. Removed the plugs again 2. Rolled the #1 piston back 10 degrees 3. Installed stop and turned it to touch piston 4. Rotated the dampener CC until it stopped. 5. At first I got a few questionable readings but after rotating the crank back and forth a few times" carefully I ended up with the piston stopping at approximately 5.95 ATDC CW and 5.95 BTDC CC. This corresponds to the readings I got with the degree wheel procedure and still puts meit seems perfectly at the PM1-4 on my flywheel? I cleaned up my cams and pulleys, assembled the pulleys in the configuration they were in before i started, put the nuts washers and o-rings on finger tight, used Redline assembly lube on everything and put #1 & 2 cams in. Will continue next weekend! Thanks for everyones suggestions. Let me know if you see anything I did wrong.... Rob Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Just some musings here. I had to firmly tap the pulleys off the camshaft with a rubber mallet, and tap out the pin with a punch. It was obvious that the pulley had never been removed from any of the cams. I also noticed the o-ring looked in very good condition but replaced them after coating them with oil. The pulley/cam showing no damage or burs but had to be tapped back on and fit extremely tight. For those who have done this procedure before. How did you remove the pin and turn the pulleys without removing the belt tapping off the pulley etc... I thought for a second about putting some lube on there when I assembled them but my conscience told me not too. I did not want any to get flung about later on the belts. I keep think about how my car was the best running 308 I have ever seen, and what if after changing the setup the cars does not run as well...... I am hoping that the measurements are as spot on as the flywheel and I can continue my assemble without much delay. I am worried my engine will suffer the garage queen syndrome if it takes much longer. I am also not looking forward to torquing the nuts back on the cams. Peter loaned me this very cool tool in my pics above but, still I am not sure how to do this without risking a mishap. I do not want to use a impact wrench, so still soliciting suggestions. I apologize for all this angst but this car is like a child to me, and has been not only a dream but one of the most pleasant experiences of my life. I love working on it but remember how fun it was to drive also. I wish one of you lived closer, obviously someone with my warped priorities and work schedule has few freinds............ at least ones i could trust to lend a hand on something this critical. Rob
I'm not sure if I mentioned this before in our emails or our phone calls, but it is around this point where you lock the cams (in the positions where all of the marks are supposed to line up) down with the pieces of paper under the cam bearing caps. You then install the pulleys - without the pins - put the bolts on and leave them loose enough that the pulley can still rotate, install the belts, install the tensioners, LET THEM TENSION THE BELTS and this will cause them to rotate a bit and then check the holes. Whichever holes line up the best, install the pins. Install the washers, bolts - but don't do a final torque yet! - remove the paper from under the cam bearing caps and give the motor two spins (to give a full four-stroke cycle). It is now the time to do a degree check, so go through the cycle and confirm opening and closing points. If anythings off, get the engine back to TDC #1 (where all the marks line up again) and do the above procedure over again, this time moving whatever cam that is off, by whatever amount that you determined will get the timing correct. This can be done by replacing the pin in the hole before, or after the current one to bring the timing up to spec, by that much. If I'm not mistaken, our cams have 5 degrees between each hole (didn't Steve M. post a chart stating these degree amounts?...). PLEASE, ANYONE ELSE, CHIME IN AND LET ME (AND ROB TOO) KNOW IF WHAT I WROTE ABOVE IS A CORRECT PROCEDURE... I know it's a freaky thing, but trust me, it'll do the job - it makes you wish we had the later cams with the hex machined on the shaft so we can hold them with a normal wrench... Remember, you can't use an impact wrench to tighten these nuts to the specific torque rating.
Peter and Rob, The degreeing procedure you stated above is very hard to get right. If you are trying to achieve a valve lift of x mm at the crank position of y degree, you turn the crank until you get x mm lift, lock the cam down, remove the bolt and the dowel pin, turn the crank (back or forth) to get to Y degree position, insert the pin, put the bolt back, remove the lock devices, turn it overe 2 to 4 cycles and recheck you work. Move on to the next cam. If you are trying to achieve maximum valve lift at 256 degrees (I made that up), then you turn the crank until you find the position of maximum lift on the cam shaft, lock it down, remove the bolt and the pin, turn the crank until you get to 256 degree position, insert the pin, the bolt, torque it and you are done. Check that cam and move on to the next cam. The hard thing with this procecure is the belt tension makes the dowel pin hard to remove. It makes me wish Ferrari has used dowel pins with a threaded hole (like Porsche) so that you can insert a tool and yank it out. Rob, you should have coated the pins with some form of lubricant on assembly. Good luck. It is hard to do, but also elevates your stooginess level.
You need to add more steps here because the resolution of the pin hole pattern is rather coarse (3 degrees), and you only get the fine 1 degree resolution by using the pin hole pattern + changing the relationship between the belt and the drive pulley -- i.e.: 1. If you install the cam pulley and a particular hole lines up well -- great, you got lucky, use that hole, and you are done; however, 2. If you install the cam pulley and no particular hole lines up well -- move the belt relative to the (fixed) driving sprocket by two teeth and reinstall the cam pulley and check again. 3. From any random starting position (that doesn't work well -- call that 0), you might need to move -6, -4, -2, +2, +4, or +6 belt teeth to get the setting where one set of holes lines up within the nearest degree (+/- 0.5 degree). Here's the chart again showing how the pin hole pattern + skipping belt teeth gets to the fine 1 degree resolution: Image Unavailable, Please Login
Gentlemen, thank you. What I presented was the method - going by memory - of how I did it. I suppose I was lucky because when I lined up all the marks and went around and checked degrees, I was literally spot on. And I say literally, because I think there was an instance where the timing was off a half, or maybe a full degree - well within tolerance (no?).
You know...I wrote this thread and have tried to just let it evolve. I think people over think this process. This is not rocket science. Guys with 350 chevy motors can do this while filled with beer! First step is to set the cams up always at the assembly marks. From that point there is a bell curve of how many degrees off these cars are from these marks like my wild a$$ guess is that 90% of the cars are within 5 degrees of the assembly marks and on the other extreme zero cars are 20 degrees from the assembly marks. Many are spot on. Many are off some very small amount. The further out of wack the timing is from the marks the less likely that timing is correct and would bare more close scrutiny of your technique. If you time the cams and find you are spot on you probably did it just fine. If you are a couple of degrees off you probably did it just fine. Your resultant closeness to spot on increases your likelihood of having done the job correctly. Modern manufacture is very good. Common sense goes along way.
FBB, Thank you for starting this thread. I had always wanted to check this even though now i am more surer than ever that my cars cams have not been altered since it left the factory. I still wanted to check to see whether I could improve on its settings, not sure who had worked on this aspect of the car before. After careful thought, I am going to proceed using the original baseline as my starting point and if my measurements show a significant diversion from the specs i will adjust as necessary. I feel that my car was one of the truly blessed GT4's and have had few problems with it and it has always surprised me with its power and grace. I have precious little time to work on it (lately) but after about a month of weekend have determined that my flywheel is at TDC almost exactly. 2 of my cam marks were spot on and a two were a tad off. I will be interested to note whether these match the factory specs for the car. My mentor Dave H suggested I do this and since I consider him an expert I am trying to live up to his expectations. To those who think I am taking too much time. I have done this ( taken my time) over the last 16 years and found that careful research and execution beat out speed and impulsiveness almost in every instance. My goal is the most perfect settings I can arrive at, no matter the time, and or effort, which i doubt that few can argue with. After 16 years of work on the car nothing though has left me with so much doubt and or fear of misjudgment and or failure to proceed correctly. My major concern is the power, response and drivability of the car which was perfect. I wonder how I could improve upon this but will not stop until I can say for sure i tried my best. I feel I can do no less as a devoted Tifoso...... Image Unavailable, Please Login
You are on the right track. Dinking with these toys is a labor of love. Take your time because you enjoy it. None of these really should be a major concern because an error in any of these areas will cause no damage. The only really thing that should be a concern is if you get some wacky timing numbers and your results are way far away from the assembly marks. Under those conditions pistons would hit valves in our interferrence motors. Also, it is know that the setting for timing Ferrari has chosen are sometimes not for power or response or driveablity. You can see that in early cars such as the 308 line that had euro and USA cam timing specs due to the different smog issues. All that is gone in modern times as all the mechanicals of euro and USA cars are basically the same. Racers also routinely play with cam timing in attempts to tweek for their specific needs. So your perfect timing by the book may actually not be optimum for your car or conditions. What people do not understand today is that cars are not a chassis and not an engine not a gearbox. They are a "system" just like 3 point seatbelts, ballistic retractors, and airbags are a "safety system". Each part relies on the other and cam timing needs to be optimized for the system.
You certainly have a point here. In Allen S. Bishop's book: "Ferrari Guide to Performance", there is a sub-chapter, written by Mark L. Dees that discusses valve overlap and how with the beauty of this twin-cam setup, the cam positions can be altered to change where the power comes in. Last week, I drove a friend's Lancia Scorpion that has twin-carbs and altered cam timing and I was really, really impressed. I've driven Lancia Scorpions before and especially one with twin carbs, but this car just blew them away. Frankly though, I'm always amazed at how well the GT4 can cope with everyday traffic with these stock settings and yet, when you open the car up, your travelling well into jail territory. Of course there's potential, but then, the nice driveability at low speeds would be sacrificed, and in reality, that's where you'd spend the most time driving.
FBB and others on this thread. Thanks so much for this thought provoking material! I have been reading and re-reading in anticipation of finishing my valve adjustment and ensuring proper cam adjustment. One thing I continue to have a problem with, however, is the differences and my perception of inconsistencies in the two methods described to measure the cam timing: valve tappet opening/closing vs. lobe centerline. The lobe centerline makes perfect sense (assuming symetrical cam lobes) by the addition of 14* + 53* + 180* equaling 247*, then dividing by 2 and subtracting the 14* to come up with the 109.5* reference mark on the degree wheel. All of these measurements assume crank degrees. But then the inconsistencies bother me. When measuring the valve tappet opening/closing, this starts at 28* and ends at 106*, supposedly corresponding to 1/2 degrees on the CAM of 14/53. How can the numbers be crank degrees in the one method and cam degrees in the second? Further, how can lobe centerline correspond with 109.5 on the crank (this would be maximum lift), but in the other method 106* is where the tappet closes.... What am I missing?
Dear Friends, I got a late start this weekend as I had a stripped thread on one of the tensioner bearing support stud. That makes 3 on the front head and none on the rear one, proably more porous casting? Anyway I put on the belts and the cam cap marks are all very close. For discussion purposes, after belt installation the rear exhaust cam is perfect on the marks. I set up the dial indicator so that any movement started at 0, as soon as the dial registered .5mm, I checked the degree wheel and it showed 18° It was getting late and I kept over shooting the closing mark, so I did not record the closing figure as I felt it was inaccurate. If we use FBB calculations 18÷2 = 9°, which cannot be right. If I use my fuzzy math I multiply by 2 and get 36°, the WSM says is the correct opening of the exhaust is 36° before TDC not BDC, but in the diagram below it. I guess I am not getting something, look I was a drummer! What does this mean, here are some pics below. I wish I were smarter..... hey my timesert came out perfect!!! Rob degree wheel challenged! Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
The WSM procedure states the opening and closing angles at .50mm of valve clearance. If I'm reading your dial indicator correctly, you're measuring at .050 inches of clearance (actually lift)...Although prefer to set the clearances with the appropriate shim to 0.050mm and then detect initial bucket movement. The factory does it this way, so we're off the ramp of the cam, hence a more accurate way of measuring the opening point. I guess the way you're doing it will work... Yes? Image Unavailable, Please Login
I did not check your math, but that is a cool rod screwed into the sparkplug hole to hold the dial indicators.
David, I was only following several posters early in the thread who said the measure it this way, obviously I did not understand what they were talking about. You are right that is a.001 dial, I thought it was hundreds of a mm. I do not have much experience with these. I guess I need to check which shims I have in there and order some to check it that way. I want to do this right but was hoping not to break the 2 year mark for my service! Thanks for you advice. If I am clear. I need to put in a shim to get .5mm then measure the first movement of the bucket and check the wheel?
Sort of related. O ring sealing the pulley bolt, anyone want to volunteer where this goes? Parts diagram and existing placement suggests between the pulley and washer, but have found enough dubious "fixes" on this thing to question that. Seems very easy to extrude it under torque before the flat on the washer locks on the pulley dowel, no idea if it's original dimension though. Pronounced waisting on the bolt between the grip and threads, might suggest it should go there perhaps??
+1 does it have a blow-by port to bleed off compressed air? who makes it? Thanks for sharing your service - very interesting read! Rgds, Vincenzo
Bolt goes into the washer and then the O-ring. The shoulder has a recess where it rests over the locating dowel. by the way, i was going to save this for later but now is a good time. Porsche locating dowel on the 911 camshafts SC-Carrera models have the same dimensions as the Ferrari one. The big difference is 1) it has a threaded hole in the middle so you can screw in a tool (like a small bolt) and yank it out while doing the cam timing. It is much easier. 2) it does not have a shoulder so it sits lower into the hole, and that is fine if you want to leave it that way. Or, you can just remove it when you have found the final location and replace it with the Ferrari one.
Cheers! OD of the ones here sit on the part line of the pulley and the hole chamfer in the cam - so suspect they've been picked out of an O ring kit, with near enough close enough....might try a slightly smaller one with a larger section.
the threaded hole found in the cam timing pins in Ferraris just so happen to be the thread size of the end of a spark plug! Been using old plugs to time cams for 35 years.... FWIW...
Friends, The shaft w made by Peter in BC. I think it has a bleed by as I hear a whoosh sound as the piston moves to TDC. I checked my shims and am going to get a fe from a local Volvo Dealer tomorrow. He asked me if it was for a gas or diesel motor becuase they were different. I told him they were probably for the gas engine. The measure 33mm in diameter. Unfortunately my #1 intake has a 3.45 shim and my clearance is .229 so i figured I need 3.179 to get to .5mm however Ferrari goes to 3.25 & Volvo only goes down to 3.30. I plan to spend all weekend tring to get some better figures...... I wish FBB would explain the center lobe procedure so I could understand it. Rob
