cam shaft fitting and cam seal help please "328 Euro"

hi everyone,
After doing many other small jobs on the 328, i thought i would go all in and this winter and do my own cam belts/tensioners (hills) and those leaking rear cam sills, what could be so easy NOT

Sorry no pics at the moment as IPAD is dead, so using my old computer and haven't had chance to transfer any images across yet.

Now please bear in mind I AM NOT A MECHANIC, just an enthusiast like most on here but the help and support you give makes me want to have ago myself.

So here is the story so far.
i have read and printed as many threads about cam belt changes---Birdmans
i have read about how to adjust my tensioners and mark up correctly getting all the marks to line up and i made some hard wooden clamps for my pulleys.
all above i'm fine with apart from some major cursing from me trying to get that bloody air compressor out of the way, what a royal pain that is, no wonder people just remove it
i'm really looking forward to putting that back :-(

Top rear Cam Cover is now off and my next job will be to remove the Cam Shafts and then fit new O'rings and Cam Seals, so

Question 1 what is the correct procedure to remove/Re-fitting the Cam locks----work from the middle out OR start on the out and work towards the middle, or it makes no odds as long as you release all the locking nuts equally as you move in or out?
goes without saying to keep all in same order for re assembly.

Question 2 What torque are these Cam lock bolts done up to please.

Question 3 When the pulleys finally come off are they keyed like a wood ruff screw/hexagon shaft etc couldn't find that answer anywhere or is it the pin i can see into the holes on the pulley--I've taken loads of photos and marked up certain areas ready for removal, any tips i need to know about?

I do NOT have an impact wrench so will take the complete cam shafts (inlet/exhaust) to my mates and use his to get them off and tighten back up to, i read they are 72 ft-Ib which i convert to 97/98 Nm as my torque wrench is only in newton meters, tensioner bearings are 40.5 Ft-Lb so are 55Nm.

i have just read mikes thread https://www.ferrarichat.com/forum/threads/camshaft-seals.605542/#post-146843481 about his experience on a GT4 cam seal replacement so will be careful to cut off the excess gasket and to put a dot of sealant up to the O'ring.

Question 4 looking at my old gaskets that are on my cam covers they have only used a little blob of additional sealant up to the O'rings, is this a good idea.
i was planning on using sealant on my gaskets all around, like when i did both my oil and transmission pans (no leaks still)-- let me know if this correct

Is there anything else i need to know about?? like oil up the new O'rings and Cam Seals on insertion is this a good idea like any other seal.

Bear in mind I have never done this before so even the smallest tip/insight that you might think is surely obvious to you, will not probably be to me, so post up you helpful advice to a newly baptised Cam Belt/Cam Seal Fitter please

many thanks in advance and as soon as I've got my Ipad working ill post some pics up
thanks again

 

#3 - why are you taking the pulleys off?

overall - download the WSM (get both the 308QV/328 and the Mondial8/QV workshop manuals as the Mondial book has more Bosch CIS info in it so you'll want both. They have all of the torque specs in a table and they are even listed in metric values for you.

https://ferrari.cdyn.com/

 

Based on your questions you have no idea what you are doing. But that is OK! You could really get into it and cam time with degree wheel yada yada yada. You could take an entry level step with consumer acceptable performance that 99% of owners would be just fine with and learn alot this service interval and then get more brave and deeper your next service interval.

That said you don't need cam locks
you don't need to take the pullys off 90% chance.

In general what you do is take the cam shafts out and the cam seals will slide off the shaft. Replace cam seals put cam shafts back in with assembly marks lined up.
Here you might need to loosely lock the camshafts so they don't move unless you got 4 guys to help you hold things from moving. You can safely use the matchbook trick to hold the camshafts as long as a hammer is not the 1st tool you always pick-up regardless of the job at hand. Once all shafts are aligned replace the cam belt with tensioneer and release tensioneer. Then take out all the matchbooks. Hand rotate the crank in the DRIVEN direction with light force and watch all cam marks come back into alignment. Do this for another revolution. Recheck your tension on belt. You are done! Footnote....some people mark the cams with nail polish. It is OK to do that especially if you want to make sure you put things back the way they came off. But the assembly marks are the factory referrence point. Either should work for you or use both to co-witness the other.

If when turning motor and you feel you can't you have a problem. Go back to the beginning
If the marks are way off they may have been that way before or there is slop in the system and it is possible because of all the moving parts that you need to unpin cam cogs and reset that way. I think unpinning cogs is essential but is intermediate cam belt changing. I think degree wheel cam timing is advanced.

JohnK is big on telling everyone the math of how belts don't stretch etc and basically ally you EVER need to do is the beginner level method. In real practice all the slop of all the moving parts and the new stiff belt make the beginner way sometimes not workable. So then you have to unbolt/unpin cam cogs.

I have always said the best way to at least guarantee the Ferrari assembly mark position is to unbolt/un-pin the cogs. From there you will then have a referrence point for the next advance step cam timing. Your car will run fine on just the assembly marks. Many pro shops only use assembly marks and don't even own a degree wheel! Many a porsche mechanic tasked to work a ferrari has set belts to assembly marks not knowing that these motors should be cam timed for optimal performance.

No RTV on OEM gaskets except at the base of the oring seals where there is a gap. Too much RTV can end up in oil galleys. I like HondaBond as the best for this purpose.

cam shafts have holes cogs have holes pins lock both together via the holes

 

The phrase you WILL Learn to HATE.

'WHILE YOU'RE THERE ...'



While you're there, I'd:

- Check valve the clearances.

Of my 16, 9 were outta spec and 5 by VERY WIDE margins.

- Check/Time the cams. Especially w/a 4V motor. I am writing a spreadsheet that after you plug-in the crank degrees at which the event actually occurs, it will graphically show you how to pin the cam and cog and how to rotate that as a fixed unit under the belt clockwise or counter-clockwise to get the max possible outta the system of -6° - 0° - +6°

Ill be posting BETA version very soon.

 

Let try to straighten this out for once and for all. I have never said that belts don't stretch. Just that: 1) they don't stretch much when new, 2) stretch of a new belt is consistent as the belts are design to have a certain elasticity; I don't have the data handy at the moment but with a load well above the max allowable tension the stretch of a new belt is less than the belt length tolerance, 3) when installed and tensioned the difference in stretch of the new belts will be insignificant is tensioned as recommended, 4) stretch with age will only move the timing off from what ever it was when the belts were initially installed and tensioned. So by the time you change belts, if stretch is significant your timing will be FUBAR and installation of a new belt by swapping would tend to correct it. When replacing a belt the timing variation between that with the new belts and when the old belts were new will be dictated by the difference in the initial length of the old and new belts which is set by the manufactures tolerance, and which works to be to +/- 1 degree if the cam pulley pins are not moved, and the belts are properly installed.

Whether you have to removed the pins to get the new belts on or not is not the issue. If you need to rotate the pulleys a few degrees one way or the other to get the belt to drop in, it really doesn't matter if you remove the pins and replace them in the same position, or leave the pins in and rotae the cams a little, just so long as the same teeth on the belt engage the same notched on the pulleys. If you insist on placing the pin is a new position to correct for belt length tolerances then there are a host of other issues that can make this endeavor in vain.

If you feel the need to retime the engine then you must take into consideration that there is also deviation in finding TDC each time you do so and the timing will only be as accurate as your ability to set TDC consistently. Unless TDC is accurately indicated on the engine and can be indexed and locked, errors in finding TDC can be as great, or greater than that which may occur from a simple belt swap. Every measurement has an error band. With finding TDC this is because the piston movement in the cylinder is a very weak function of crank angle around TDC and, additionally, due to bearing clearances there is an angular range were the piston doesn't move up or down the cylinder at all call the dwell. This is why a piston stop method is a considered more accurate method of finding TDC than a dial indictor. However, there are inherent errors with that method as well do to the offset of the wrist pin in the piston. The error with a dial indicator is because you simply can not know whether you are at TDC without moving the crank past TDC. For example you watch the dial indicator. You rotate the crank slightly and it indicates the piston is rising. Rotate it more and it rises a more but a little less. You continue to do this until the dial indicator doesn't move at all the on the next increment or starts to indicate that the piston is moving down. The best you can say is that DTC is somewhere between the last 2 crank angles. It would appear that you can improve the accuracy by rotating the crank is smaller angular increments. But the fallacy there is the related to the sensitivity of the dial indicator. You get to a point where the piston's movement insensitivity to crank angle combined with the dial indicators resolution make it impossible to reduce the angular increment of crank rotation below a certain limit and have the indicator respond to change in piston position. this is related to digital sampling and the Nyquist theorem. Add to that, even with infinite accuracy, two positions for which the indicator doesn't move only indicates you are in the dwell. That implies that both position are past TDC and TDC lies some where between the last potion where the piston was moving up and the first position where it was in the dwell. Because of all the accumulated error specs like "set the timing to xx degrees XTDC, +/-1 degree, actually mean you probably are setting the timing to XYDC +/- a couple of degrees.

So my position is, has been and will remain that if you have confidence that the engine was correctly time when you started, swapping belts will assure you that it will be timed correctly, to within acceptable tolerances as noted in the WSM, if you do a correct belt swap.

I'll go further and say the given any two mechanics the same set of tools and have mechanic A set the timing and then have mechanic B check it, the odds that B will fine A's work

Image Unavailable, Please Login is about the same as hitting the slots in Vegas. This is most likely why those who insist on retiming the engines are always finding that the last guy got it wrong when in fact, they are both correct, just at different limits of the possible range of accuracy.

But as always I will add the disclaimer: It's your car, do what you want to do.

 

Love to see that but again, how are you going to account for limits on accuracy of finding TDC. Granted that TDC is marked on the flywheel of a 3x8, but even taking that as gospel there will always be some error, perhaps small, in aligning those marks by eye.

 

John,

I think you really need to do this job and get a real world education. There are many many reasons for doing things a certain way. An example is some people will work on a car and put the nuts back on the studs so they don't loose the nuts. I always remove all nuts and throw them in a bucket. Fasteners should always be either on tight or off. Does it really make a difference when the end goal is you got the A-arm back in? Yes it does if you value your life! Think about that...

 

I have to ask why you keep making false statements implying I've never done a belt job. I'm effin' 72 years old and was building high performance engine in high school. Give me an effin' break. We see things differently. And one difference is I've explained my point of view numerous times in sufficient and excruciating detail. You just babble on implying that I'm apparently glue less and have no real world experience.

Maybe you can strengthen your position by explaining in detail how you can consistently find exact TDC using you beloved Ferrari method? Or some of those many many ways? WTF does an A-arm a containers have to do with timing an engine? I've explained in detail the error sources in constantly retiming the engine. It doesn't mean retiming is a bad thing. I've never said that. It just means that if the engine was timed correctly before you change belts and to do a swap correctly, retiming won't necessarily make it better timed. Most likely it will just make it different. Maybe + 1 degree instead of -1 degree. And I have always stated that it is necessary to be confident that the engine was correctly time to start if you do a swap. Why would anything that we manufacture ever need to have tolerances if it were possible to be exact 100% of the time? I'm not saying you can not be close, but to do so repeatedly and find the exact same result for TDC would require prior knowledge ( That doesn't mean you did it before, but more like it was done before and precisely marked. But even the mark would have to have some tolerance). Measurements are not certainties. They have error bounds for the reasons I have explained. It sounds simple to say pull a spark plug from #1 and stick a dial gauge in there and rotate the crank in the direction of running until the indicator stops and that's TDC. But it ain't so simple in real life, is it? To start with you can't tell the indicator stopped until after it stops. which by itself means you have pasted TDC.

I think one of your point has been that aligning the cam marks can be several degrees off and that when replacing a belt just aligning those marks by moving the pins isn't sufficient . I agree 100% with that. IF you pull the pins and mess with the pulleys to put the belt on, aligning the marks is not sufficient. But if you put the pins back in the same holes they were in, it's a completely different thing. And you can't go by where the marks were when you took the old belts off because of our old friend, belt stretch. So where the marks were with the old belt won't be where they are with the new belt. But, to within the angular variation associated with belt length tolerance, the marks will be where they were when the old belts were new. The marks can only be used as a reference. They should be close or you may have skipped a tooth when placing the belts on the pulleys. Think about those marks for a second. The cam journal is what, about 1" in diameter. That a circumference of Pi, 3.14159" or 0.0087" degree. So the mark itself is what, 2 or 3 degrees wide? That doesn't mean they can not be accurate. Certainly with the manufacturing capabilities that existed even in 1975 there is no reason that the cams and cam caps could not be marked during manufacture with sufficient accuracy be within the required tolerances for cam timing. But I except that they weren't. Ferrari was sloppy.

Anyway since you claim to have vast experience that I, in you eyes are lacking, let me ask directly. How many times have you changed belts on one of you cars. Not how many belt changes have you done, but on a single car, how many time have you changed belts. Assuming more than once, then you have timed that engine more than once. If you did it right the first time, when you did it the second time, how far was the timing off after replacing the belt assuming you started with a correct belt swap? Did you have to put the pin in a different hole? What was the reason for this? How many degrees was it different form the previous time after just the swap? What changed other than belt length and if, how did it alter the timing more that what is possible give the belt length tolerance? You have never address these questions for all your real world experience , and I suspect you never will. I suspect you never checked. I suspect you can not because from reading many of your posts I get the idea that you have never really started the process from a correct belt swap. I get the impression that you lock the cams at the reference marks, pull the pins on the pulleys, put the new belts on without regard to what tooth meshes in what notch, put the pin back in a hole the lines up reasonable well and carry out the timing from there. In such a case it is no wonder that you are constantly moving the pins. You babble on about the real world but dismiss things that occur in the real would like the errors in finding TDC and the lack of repeatability. These are real world things that engineers have to consider when they tell mechanics how to do something. Just remember, when you harp about the "Ferrari" method you are quoting an engineer.

Good hashing this out with you, but drop the bias. Answer some of the questions I've put before you for years.

 

Yup....I think your posts say plenty. Yawn....

 

Simple questions, you change the belt and time the engine. Then you take the belt off marking which tooth came from which slot on the cams and drive pulleys. You install a new, different belt such that the belt teeth fit in the same pulley slots as the belt you just took off leaving the pulleys pined as they were. How much will the timing change? Why does it change? Simple, honest question.

 

Don't confuse the milkshaker. You are getting to and area few understand or do. Milkskaker should ignore our banter for the sake of his understanding.
That said:
Have you ever done this job? No or you would know the answer. Just do it. It take 1 hour. All your questions will then be answered. I will tell you this last truth. When cam timing you may come close on the degree wheel to your target and 2 or 3 holes might look perfectly lined up for the cog pin yet none of the 3 will allow the pin home. A very slight tap of the cam lobe moves the shaft a visually imperceptible amount allowing precision holes to line up and the pin to seat home. Do this and you will see big movements on the dial gauge. Try it you will see. Then you will understand the total lack of precision in your perfect theory. Your problem is not being able to reconcile theory with practice. We are both right. The problem is you cannot achieve the perfection required by your method of just swapping belts. That is why cam timing with a degree wheel and dial gauge exits. We even go crazy in racing circles to use biggest diameter degree wheel possible for best accuracy. Anyone who uses a degree wheel knows this.

 

Paul, if you already have the cams locked in position based on the cam index marks and crank at TDC, I would mark the belts and all three pulleys on each bank with a white marker so you can easily get the cams to the correct positions after the new seals and valve clearance is done. You can transfer the marks to the new belts (count teeth) when you reassemble.

 

You see Fbb, your refusal to answer a simple question speaks more volumes than everything I have written on any subject here on FChat. You employ the same old tactic, avoid the question, change the subject. You imply I don't know the answer, but it is you who has, when asked directly, with your vast experience, refused to enlighten me and all of Ferrari Chat. That's either arrogance or ignorance. You always fall back on statements like "you can't achieve perfection....". I didn't ask about perfection I asked what would the error be? It's simple, it could be +/- X degrees, you fill in the X.

"A very slight tap of the cam lobe moves the shaft a visually imperceptible amount allowing precision holes to line up and the pin to seat home." So X is visually imperceptible. What's that, like 0.25 degrees?

 

Hi all
I didn't think this thread would get you both so heated . Never mind good banter and good technical stuff.win win for those who know there subjects.

Moving on and looking forward, I did not realise that the collar with the o ring and Cam seal would just slid off along the whole length to the left of the cam shaft without the pulley coming off, so all is now straight forward and I'll proceed with fitting the new seals/o'rings
I thought the collar would have to slide off to nearest end of the cam shaft (pulley side)

I have all the torque settings now and alignment marks/photos to proceed now, so all should be could now until I have to put that compressor back in place.
For me the task has been a positive learning experience, but saying that I haven't finished yet and turn the starter, so we will see and report back, I'm only able To do a bit at a time so it may take me a few weeks at this rate but I'm no hurry and the weather here is crap so it's going nowhere.

A couple of pics of my first Cam out and the collar that just slides off, look closely and you can see the nick on the O'ring causing my leak I believe

Image Unavailable, Please Login Image Unavailable, Please Login

 

With the crank at TDC it’s safe to rotate the front cams and test the clearances with a feeler gauge. Then remove front cams, rotate crank 90 degrees and check rear bank cams for clearance. Absolutely worth doing while cams are out.

 

Leak is probably from cam seals not the oring seals but it is possible. The nick looks more like what we see all the time. It is the part line as the ring is squished between head and cover. notice the green old gasket and the red rings on the gasket. That is an OEM ferrari gasket. That is why you don't need RTV except at key points and just a dab. There are cheaper non-oem gaskets available for 1/2 the cost without the red rings and those you need to goop in some way to seal. Both gaskets are ok you just need to know how to handle them. As an inexperienced DIY'ER I would recommend you buy your parts from Daniel at Ricambi America. There are many reasons many pros use them. Daniel always sources the best parts and stands behind what he sells. When in doubt he always gives the benefit of the doubt to customers and can always get you what you need. He is the best. You can source parts cheaper but you need to know what you are doing like finding a bosh part that fits ferrari or the source for the cheap gasket or how to get non-proprietary bearings from a bearing house. Eventhough my time is free as a diy guy I'm lazy and do not like being irritated. So I buy from Ricambi because I know I get what I need at a fair price with excellent customer support with very little time spent procuring parts. It is just not worth my time to make 4 phone calls to get parts for 1 job.

 

John,

Your last statement is correct. But we can try to make it so small we can't measure it 'accurately.'

I'll post the Spreadsheet soon for you all to tear apart.

I WANT YOU ALL to DO THAT so we have the best product available for ALL FChatters timing their cams to use for FREE.

That said, the flywheel mark ... within reason, it doesn't matter where it was stamped/forged. It can be OFF a country mile and probably is. By itself it, it has NO MEANING and MEASURES NOTHING. The Flywheel was likely just bolted onto the end of the crank. I doubt any indexing was done here as there is no reason to.

When combined with a Dial Gauge Indicator measuring piston movement to find True TDC and then adjusting your Flywheel Pointer to suit, THEN that flywheel mark 'TC 1-4|' means something. My OEM pointer was 'OFF' by a few millimetres on the flywheel. I 'Fixed' that with my improved pointer and painstakingly adjusting it using a helluva magnifying glass.

I then, usings a nautical navigator's double-pointed compass, went so far as to measure-out and mark the valve events on the flywheel itself. Why? Because I wanted something to reference my Degree-Wheel readings to.

Finding TRUE TDC using a Dial Gauge Indicator is Essential. ONCE. The FIRST TIME one 'Dives-IN.' After that, let your conscience be your guide. I probably won't do it again until I have the motor rebuilt in about 3 years when the sodium valves I assume are still in there, Come OUT.

I used a piston-stop first, as at the time I didn't have the cash for a GOOD Dial Gauge. My new dial gauge measures movement to 0.001s (1/1000th) of a millimeter. With that sensitive a gauge, which is likely 'Over Kill,' you can actually see the piston 'dwell,' just 'sit,' at Actual TDC, as you sloooowly continue to advance the flywheel and one can even measure and take that fraction of a degree duration of dwell into account. I did. I Adjusted and Set my remade, much sharper-pointed Flywheel Pointer off of the Center Point of that dwell duration observation.

With the piston-stop I used, when I measured that against the dial gauge, I missed TDC (to include half the piston dwell) BY about 0.003 mm. And it was actually pretty repeatable out of about 10 different trys. Luck? IMHO ... YOU BET.

To a point, the accuracy of the initial placement of your Degree-Wheel on your crank doesn't matter either ('Center-to-Center' certainly does). Not until you put a pointer on it and adjust it too, to read TDC. Then, it too is 'Indexed.'

Once that is done, you have three seperate TDC Indicators all Indexed to Actual TDC, Piston #1: your Dial Gauge Indicator, your Flywheel & Pointer and your Degree-Wheel and Pointer. NIRVANA.

My adjustable Crank/Degree-Wheel Pointer was a repurposed and fine-point ground and painted coat hanger section I clipped to a Cam Belt-Cover stud. Had I thought of it then, I would have rigged-up and fixed a laser-pointer instead of a coat hanger as my Degree-Wheel Pointer. Absolutely NO 'misreading' that!

But what I did do, is I used the parallax of my two eyes, one to read the pointer and the other to ID a near and a distant fixed reference points, so I could position my head very, very close to the same place every time to read the Degree-Wheel Pointer. (Cannon Artillery uses a similar method to 'lay' their guns so their accuracy w/o GPS assistance is about +/- 10 Meters at 17+ Km with a 'dumb' projectile.

I did this as I quickly discovered one can easily 'misread' a Degree Wheel and Pointer by more than +/-1° merely thru sloppy head/eye placement. Getting your Pointer as CLOSE to the Degree-Wheel as possible W/O Touching It, helps greatly in removing this source of 'SLOP' as well. That is why using a laser dot as a Degree-Wheel Pointer is the 'Perfect' Solution.

With the cam & pully holes, pin and belt-teeth pitch system alone, the closest one can get is pretty much 'Dead-Nuts-ON' or +/- 1 Crank Degree OUT. There are NO other options as that's the hard physics of the parts and math of the system and within the WSM's allowable variance.

All but the Absolute Anal-Retentive should STOP Right There, buuuut ... NOPE.

There are two ways I know of to 'Fix' and get 'under' that half a degree CAM error even to 'Dead-Nuts-ON,' should it occur.
And on one of my cams it did. The event occurred at a measured 17.5 crank degrees. $[i+ !!!

One method to 'Fix' this, several members/posters here, have the ULTIMATE solution for. It is NOT Cheap, but it is an ELEGANT, and EASY to employ, Solution. The other way I know of MAY ONLY cost you ... your life.

IF you have a Wife and 'borrow' one of her 'tools' and employ it thus ruining it, to accomplish your task of 'getting rid of' that remaining Cam/Valve Event fraction of a degree error, she might just Kill You. But numerous other outcomes are possible as well.

I took a helluva chance and today I have BOTH options in my Ferrari toolbox.


NOW ALL THAT SAID, Please allow me to clear-up some misperceptions I may have caused:

- Q. Isn't there inherent 'Slop' in any mechanical system especially one made in the 70's and 80's?
- A. Of Course ... and often LOTS OF IT. One who wants to, just does their best to ID it, determine its 'average' after several repeated measurements and take that 'Very Best Guess' into account.

- Q. Don't we 'add slop' by not using our tools or reading our indicators, EXACTLY THE SAME WAY each time?
- A. Sure we do. Again, we use what we can; Don't move things we dont have to, magnify, use additional known and tested reference points, use physics, use Anything to MINIMIZE those human-induced errors as we work.

- Q. Should we go to this level of Anality Every Time we merely change Cam Belts/Tensioner Bearings?
- A. OH. HELL. NOOOOO!!! I would NEVER Recommend THAT. NOT in a 'Street' car. But I am sure a PRO or two will kick my butt for saying so. I will accept that criticism.

The 308 QV OM states as Service Item #1: 'Check Valve Clearances every 15,000 miles. Inspect and Adjust as necessary.' By extension, that to me infers Checking/Adjusting the Cam/Valve Timing as well, because the time interval for that specific act, I couldn't find anywhere in the OM. Perhaps I missed it?

(The Belts do have a Milage Inspection and Replace Interval specified in the OM as well, but no mention of the Tensioner Bearings. Thus many of us again infer; Change One (Belts), Change the Other (Bearings). A Service Bulletin issued later modified the OM Belt Service Schedule.)

I certainly would NOT time cams any more often in a 'Street' car, UNLESS Something necessitated me to 'popping' the valve covers for another reason. THEN, the dreaded, 'While you're there ...' would kick-in. At least for me.


My car turned-out to be so screwed-up and OUT of WSM SPEC, it was UNBELIEVABLE. I couldn't prove based on my measurments and observations, that it had even been PROPERLY Serviced just Once, since it left Maranello, in NOV 1980. But the Service Record Book says it was ...

I. DON'T. BELIEVE. IT.


If one TRUSTS the prior service history of the car as ABSOLUTE Gospel and the Time/Milage Intervals in the OM and WSM and Changes issued in the Service Bulletins have NOT been Exceeded ... ROCK-ON!!!

IF you find that ANY of those manufacturer specs have been EXCEEDED, let your conscience be your guide.



P.S. I didn't make ANY of this stuff up. I learned it all from PRO Techs who actually do these things in their own shops and no longer post here, and other PRO Techs who still do.

 

Mark,

Thanks for the thoughtful post. Yes, with a highly sensitive dial gauge you can get closer and closer to actual TDC. Again, this is dictated my the Nyquist theory. The resolution of the gauge tells you how far apart "samples" can be. Geometry tells you that when translated to crank angle the angular positions are further apart as you approach TDC. I would only argue one point, why would you take 1/2 the dwell into account? Rotating into the dwell is rotation past TDC. Agreed that it would be a small angle, but correcting to 1/2 the dwell pushes your TDC reference slightly past true TDC.

Not to belabor the point but my argument with FBB is straight forward and has gone on for years. He is insistent that it is necessary to time the engine at each belt change. I don't disagree that if you are worried about fractional changes in timing with a belt change that you would do that. My argument is regarding just how much error there can be if you just do a lock and swap. There is nothing magical about it. You either believe in 10th grade geometry or you don't. And of course there is the question of how much does a small change in actually timing actually effect performance. It's not so much that the car doesn't run correctly. It's more about shifting the power band up or down the rpm range.

Another point is that while it is true that checking timing on a car like the 355 is pretty straight forward due to the hydraulic lifters, on a 3x8 it is a little more involved being that, if you follow the WSM, it is necessary to set the valve lash on the reference cylinder correctly before timing can be checked. Just another source of potential error.

Anyway, it's really all a moot point as pretty much every 3x8 DIYer knows that a lock and swap belt change provides satisfactory results. The crux of the matter is that if you are happy with the way you car was running before the belts are changed, you be happy after doing a lock and swap when done correctly. To dispute that point is to dispute many years and hundreds of real world belt changes. Personally I couldn't care less if the timing of my 308 is a degree or 2 off. For 35 summers I get in it, turn the key, it starts and I drive. Most significant problem I've had was last year when a distributor rotor carbon tracked and I lost a bank. And of course, with my incredible life long streak of good luck, it happened on a clod start in my garage.

 

John,

Thanx for the info on the 'dwell' event.

Didn't know that ... never asked ... just ASSumed ... .

Something else to learn more about.


BTW my 308 2V is the FIRST CAR in my life I have ever done more than change the oil, filters and plugs.

Talk about a Knowledge Thursty, SLOW Moving, Pensive, Methodical and Anal 'Little Rabbit.'

 

Small update today
New cam seals pressed into collar with new O'rings (brown old ones, New type Orange)and cleaned off all old gasket, ready for cam assembly
Took my time cleaning surfaces as best I could ready for new gasket set.

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Good job milkshake! Keep going...

 

Mark, you understand.

 

Looks like a good time to do the “cam oil drain hole mod” it you need to use the jig for the job.

 

Awesome work Paul.... Just keep practicing until you do mine..

 

I have seen this mentioned some time back but I don't have the jig for that, I think drilling a hole into my engine would freak me out to much, have checked both oil return drain holes by the cam seal collar are free flowing also, no blockages.