And if you are charging $5000+ for a service on a car you have not seen before, or have not seen in 5 years, how would you go about verifying cam timing on a 348 and 355 unless you pull out your degree wheel and find TDC as well as the cam overlap. In the process of verifying that, you have performed the cam timing. Therefore, in practice, you do cam timing every time you change your timing belts as a matter of verifying it is correct on a 348 and 355. If you remove the cam shafts to change seals, or valve adjustment, there is no other way but to perform the cam timing exercise. Lastly, let's say you lock and swap and can be within 3 degrees of specs, who would want to remove the engine, do all those things and put the engine back 2 degrees out of cam timing specs? You, Dave? This reminds me of a fellow on the 308 GT4 that wants to set the cam timing to 0.25 degree of spec, while using his degree wheel with only 1 degree increments. I thought he was crazy but he insisted.
IMO, the debate over 'lock & swap' theory versus 'always re-time the cams' is trivial. In either consideration (and as any practiced engineer should recognize) there is value in the step of verification when theory is put to practice. Theory gives me confidence, but not confirmation in a specific case result. I've seen it countless times in design and manufacturing. The crank could bump or rotate slightly in that time between belt removal, and belt tensioning, especially if additional work is being done in that area to a sprocket/chain, bearings etc.. Stuff that has to be done in the absence of a belt, or otherwise is being elected to be done in parallel. A camshaft could jump or rotate slightly as the valve spring force applies rotational bias at varying positions. The point is, *stuff* happens that may not be accounted for in a vacuum, and it is a smart measure to verify your work as standard practice... lock, swap, check, adjust if necessary. IMO (again), it is a result of either ego or ignorance to not follow those steps, but that's just me. I like my i's dotted and t's crossed, and if I have a theory, I like to know that my actual, physical results have confirmed that theory. Do what thou will with your car to verify the work or determine what is considered acceptable. Also, the discussion relative to 348s adds a bit of bias to the practice, as in my personal experience it is a much easier process to simply remove the cams entirely for valve shim adjustments with their tight fitting deep buckets, than to work with the hook and spoon around the cams in-situ.
It's never been a debate. It's been a simple question put forward that no one, regardless of experience level, has even ventured an answer of any type.
It has been answered, you just don't agree with the answer because it is not in line with you theory.
Many cars are serviced by the same shop, same tech and in those situations, the tech will know what he did prior and not need to waste time doing it again. If you don't know the history, then I agree with you. Not if you mark stuff - it will go right back to the same position it was before. If you lock n swap, it's not going to be 3 degrees out.
Seriously Dave, you actually degreed your cams on your 355 and now you are telling people to lock on swap on their cars? I give you $100 if you can put the cams back to 1/2 degree of where you took them out. On high performance engines like BMW M3 and Porsche 996/997/turbo, the factory makes a set of tools to lock cam shafts and crank shaft to 1/2 degree of where they are supposed to be. You are telling me that you can do the same with a Sharpie pen markings? OK, man, it's your car.
If any car, going in for a belt change is running fine, then clearly the timing is within tolerance, so a lock up, mark out and swap is common practice on every car running a belt, once marked out properly it will run just the same with the new belt as it did with the old. If its not running the best then do exactly the same initial steps as above, then degree the engine and compare such with the marks you have just made to see if things have moved for whatever reason. All fairly simple logic, that's what we have been doing with the YB Cosworth engine since they came out, rarely does anyone degree them, they work to the factory set up marks, only when the heads have been skimmed heavily are they checked and adjusted, as the loss of metal has an affect, but even then not enough to go another notch on the wheels, so in that case adjustable cam wheels are fitted instead. I think you all need to agree to disagree and just follow the process that you are happy with as this debate is dragging down a number of threads on here now. Happy 2018
So lets say just for the fun of it you drop an engine, measure the timing with the old belts. Removes the belts. Replace the tension bearing and for the heck of it, put the old belts back on, engaged with the pulleys as they were initially, and measure the timing. According to you, Mitch, the timing would be off. What magically changed?
Paul, any other time I would agree with you. But were are expecting a heavy snow tomorrow here in New England, and it's colder than a witch's tit. So, I figure we can milk this for another day or two for entertainment.
Mitch - with the most respect, you need to pay attention to all posts, not just a few. Let me summarize: If I didn't do the work prior, I'm timing (or verifying) the cams. If I did it 4 years prior, unless I'm trying to prove something or experiment, no need to do anything other than lock n swap. And, please take a hard look at the TDC thread. I'd argue the method you may be using to find TDC will have more than 1/2 degree of accuracy. Also, if your indicator is not picking up the lifters 100% colinear to the lifter axis, you will have another potential error in measurement.
No man, I am referring to something very specific you said. That if you mark the cam shafts and remove them to change the seals, you can put them back to 1/2 degree of where they are supposed to be purely on the marks. That statement is a theory you posed. Let me ask you Dave, did you actually remove and replace a 348/355 set of cam shafts where you verified it before the removal and after the reinstallation that you have put them back to 1/2 degrees of where they are all supposed to be, with a degree wheel? If you have not done that, then you are debating theory with actual experiences. And I am not into that. I think I will go play my Gibson. The nitrocellulose makes me high.
Mitch - what are you missing? The cams are pinned to the pulleys. You mean to tell me you can't mark them and put them back exactly in the same position? How not? To answer your question, my motor (95) is a full rebuild and I've not yet assembled it but I did and continue to do a bunch of experiments as I disassemble it.
Now Mitchell is making so much sense my brain is hurting. Things make sense when you actually do them. I fully understand why pros on the clock lock and swap. Horseshoes and handgrenades is close enough for many. Sucks when diy'er are perfectly fine with consumer acceptable.
That's that fake news stuff. "You can't lock the crank" implies that you need to lock the crank. But you don't need to lock the crank. You don't need to lock the cams either. It just makes life easier. What you need, and all that you need, are reference marks. Consider the obvious fact (or what should be obvious) that when you do a belt change and retime the engine the first step is to do a proper belt swap. Now, if you can't get the new belt on with the same teeth engaged in the drive and cam sprockets as was the case with the old belt, you have bigger problems to worry about. That nail polish on the pulleys that was supposed to be a telltale sign of a swap may just as well be from a shop that retimed the cams but marked the pulleys to ensure the new belt was installed correctly.
Ha-Ha - that's funny. John has proven once again that some here cannot have a level headed exchange, presenting facts to support their position - instead emotions come out and we get posts like above
Ok, so you’re going agree that... if I perfectly degree my cams (or already had perfectly degreeded them) and I make timing marks on my cams like the factory on the cam and can jourlal.. then I tear my whole motor down, when I put it back together if I put the cams on their marks and the crank at TDC and the belt slips right on, I turn it all a couple times and see all my mark line up that now the engine might be out of time? How? Did my cams twist while sitting on the bench? If my cams where timed at those marks once they are timed at those marks always. Period. Logic. What is this argument about? I can tear my engine down and scatter it to the wind for a century. When I get all the parts back together I can still set the crank at TDC, line up my cam marks and put on a belt. My cam timing will be exactly what it was when I made the marks 100 years earlier. Period. Simple. Done. Anyone who would argue against that is living in a different universe from the rest of us.
I think some people just want to argue with certain people no matter what it does to their own credibility.