[ivymike1031]

Originally Posted by quaddriver

you dont have a degree in 'automotive design'

That's correct, my degree is in mechanical engineering.

Originally Posted by quaddriver

you dont work for any automobile or motorcycle manufacturer... you dont simply design automobiles nor any of the components.

That is wrong. In fact, I have been involved in the design of valvetrain hardware for some recent US automobile engines that you are probably very familiar with, and some that you will no doubt become familiar with within a year or two.

Originally Posted by quaddriver

So you have attacked me ad hominem claiming 'expert status' why?

Because you clearly don't know what you're talking about when it comes to the relative noise levels of different timing drive schemes. You do seem to have plenty of experience with the "I may not be an expert, but I play one on the internet" routine.

Originally Posted by quaddriver

you are not engaged in employment in any matter dealing with anything automotive on a technical level. If you were, you would not have asked for the reference on the SAEs stance on the 3800, simply because you would have HAD it on your desk
(for future reference, when you commit such blunders, especially in an online environment, your credibility is shot forever. shall we examine the other 713 posts you have made?)

You really don't know what you're talking about. I am an SAE member (since 1996), and I have several of their publications on my desk currently, mainly dealing with piston and ring lubrication, oil consumption, and recent developments in low-friction coatings. I also read their monthly magazine, Automotive Engineering, and I get the sectional newsletter. I get the idea that you really have no idea what automotive engineers do during the day (work), or what they have on their bookshelves (Roark's formulas for stress and strain, Shigley's Mechanical Engineering Design, and/or Heywood, typically, with a smattering of Timoshenko or Hartog texts as well). Do you have any idea how many papers come out of SAE in a year? I get abstracts from about 20 per month, specific to the areas of design that I'm responsible for. You try reading all that sometime (I usually don't).

Originally Posted by quaddriver

Furthermore, you would know who Mr Csere is and have read him quite often. I am not going to do for you the homework you should have already done.

Yeah, like engineers have time to sit around reading car and driver. Come on. Now you want me to write a letter to him and ask "some kid on the internet says that timing belts are noisier than timing chains. Should I abandon my several years of experience in the design of timing drive systems and adopt his bizarre and ill-formed viewpoint?"

Originally Posted by quaddriver

Ps - it is of light humor that we note you have not to date challenged any point in any of my posts on a technical level, merely the timing of suggested timing belt changes (all the while, on a grander level of humor noting that you skirted the issue that they in fact need changed, whereas chains do not, as I originally stated) I believe my correct stance at this point should be (in your vernacular): Bwahahahahahahah

Well, since you clearly need things spelled out for you, let me say it plainly. Your statement that chain drives are quieter than belt drives is absolute rubbish. Technically speaking, you don't have a clue. Read some of the articles I linked to above, or go get a real education!(as I, and several of the other people posting to this thread, have done)

If you read this thread from the start, you might have noticed that in the fourth paragraph of my first post, I made the following statement: The advantage of a chain is that it lasts longer; belts are quieter, easier to package, and offer better high-rev performance if the drive load requirements aren't too high. I stand by that statement. I don't need to "skirt" the subject of timing belt changes. You seem to be intent on misrepresenting the frequency with which they must be performed, which is not entirely surpising, given that you seem to be prone to grandstanding and make-believe.

Originally Posted by quaddriver

eh, sorta....OHV motors really only need a smidgen of oil to lube the ball/rocker assembly, pushrod end and cool the springs.

since the cams in an xOHC motor are held in aluminum, in most cases without benefit of a bearing shell, forming a hydrodynamic wedge is critical - and maintaining same across the cam. On a DOHC V, there are 4 steel cams that can wipe out the aluminum bosses in MINUTES, not miles. In the old days, OHV engine had a simple 'x lbs per y rpm' oil pressure requirement...today, the xOHC motors tend to require much more oil rpessure at much lower rpms to ensure all the cams are oiled at idle.

As for your valvetrain comments....you're all wet. Hydraulic cam followers are what EVERY manu has went to. Now note, save geometry, the parts and use of are the same - with a solid setup, you must set the clearance correctly - just having said clearance leads to a LOT of noise (just ask anyone with an older honda ;car or bike; or toyota) and it accelerates wear. with hydraulic lash, the tension on the plunger is measured in inch-lbs, whereas the seat pressure on the valve is measured in ft-lbs. In solid designs, the lobe must whack the follower which deforms the iron or in some cases steel slowly but surely. In hydraulic designs, the cams are offset ground (in OHV applicatins) to rotate the follower/lifter - wear is negligible. whereas solid deisgns require readjustment every 15Kish miles due to wear, hydraulic designs last forever. but please note, the loss of oil pressure on either will cause negative results. I have seen cam lobes wiped clean, but the vast majority as any professional will tell you will be incorrectly set solid designs - once the clearance is gone, the cam lobe is ALWAYS against seat pressure, (as opposed to plunger pressure in a hydraulic setup) Do hydraulic lifters collapse? yep, but it is so rare as to not require mention.

Of note is the use of roller followers today, I and many others have taken roller lifters out of 200K mile motors and reused them after inspection on a fresh cam. they just dont wear out.

Unfortunately, HLA-equipped pushrod engines (OHV is not an adequate description) typically rely on oil feed through an orifice in the HLA to the pushrod to get lube oil to the over-head area. Oil flow through that orifice is restricted to something in the neighborhood of several grams per minute (say 24gm/min @ 100degC). Cams in the head often get oil drillings, and a much healthier oil supply. Not all overhead cam engines use aluminum heads (see Deere). Idle lubrication is the primary design factor for the oil pump for almost all engine configurations. Aluminum makes a pretty good journal bearing material.

Honda still uses mechanical lash adjustment, with a recommended adjustment frequency of about 60k miles. Mechanical lash adjustment is also used in a number of high-perf applications, and on a very large number of heavy duty diesels. Wear is definitely not neglible at the cam-follower interface on pushrod engines. Ask a mechanic. Pressure is never measured in ft-lbs (duh). With a hydraulic lash adjuster, the expansion spring preload is not very large (say 40N or so), but the force that the lash adjuster exerts against the cam & pushrod on the base circle when the engine is running is much higher (say 150N). If you'd like, I can explain to you how a typical HLA works. There are often collase and pump-up issues with HLAs during development, usually they're sorted out by the likes of me before the likes of you get an engine. A properly adjusted mechanical system will have less force on the cam-follower interface over the base circle than a HLA valvetrain (close to zero).
Roller followers are used on both overhead and in-block cam valvetrain configurations (as noted in my MUCH earlier post).