very straightforward question if you know what im asking. are stock valves designed under the endurance limit of the valve material?

im not sure if anyone knows, but i really want to.

 

Yes. Otherwise they would not offer a warranty.

 

reason being is i would like to reuse some valves that were in a head when i bought it. next question is, can aftermarket springs with real high pressures, and a high lift, relitively short duration cam stress beyond the endurance limit? or is it alot higher than i am expecting? i havent really tried t do the math yet.

 

If the valves are perfectly straight (your machine shop can verify this for you when they grind them or try to grind them) chances are the valves are re-usable.

Also look at the tip of the valve. There should be know funky extreme wear marks.

 

i was going to get them checked for striaghtness and reground to clean them up.

thanks for the replies, you'll see some of my DIY bs again very soon.

 

If you want I have some good used re-ground valves for a good deal for you in appreaciation of your support.

Valves are ground on a centerless chuck valve facer resulting in very good concentricity. Excellent results with heads that I've provided customers.

 

With used parts you are living on someone else's borrowed time. But hey, most here buy 4th reject headers cheap, why should you be any different? Material "such as rods, cranks, valves are rated in cycles. Or in how many times they have gone up and down, when you can answer that question, someone smarter than me will give you an answer.

 

True. There is your WARNING LABEL.

USE AT YOUR OWN RISK.

 

Looks like the "Don's" are the only "engineers" chiming in so far. LOL.

 

well if under the endurance limit, fatigue life shouldnt be important. no dislocations are caused under the limit therefore, fatigue does not occur, AS I UNDERSTAND.

you would have to be basing everything around a maximum RPM correct? so if you never go past that maximum, the number of cycles is irrelevant as long as you are under the endurance limit. know what im trying to say? its more of a question.

 

Cycles normally means under normal conditions. Hard to know if the valves were operated under normal conditions. A through examination of used valves would cost more than a new set of good valves.

So with used valves you don't know of you are getting 80% service life or 5% service life. At least with new valves you should be getting 100% of the service life.

If you still want to used good used I can still help you out, but DonF is correct in his statements re borrowed time. When you have been building engines for 30+ years you know normally know better what is best for the customer.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bluedlude &raquo;</TD></TR><TR><TD CLASS="quote">well if under the endurance limit, fatigue life shouldnt be important. no dislocations are caused under the limit therefore, fatigue does not occur, AS I UNDERSTAND.

you would have to be basing everything around a maximum RPM correct? so if you never go past that maximum, the number of cycles is irrelevant as long as you are under the endurance limit. know what im trying to say? its more of a question. </TD></TR></TABLE> Endurance limit would be the number of cycles, not strength. I have alot of used parts, as long as you do not a warranty. Visually perfect.

 

you would be alot safer using New OEM valves, or aftermarket if you are worried.
nothing is better than a solid peice of mind. What valve springs are you using and what extreme rpm and lenth of time up their are you planning to build the head up to?

 

im just trying to overthink everything. but i get my ***** and giggles from that kind of stuff. why not reuse valves if you could? i just wanted a nice solid answer.

but to say that the number of cycles is important is essentially saying that it is not designed with stresses under the endurance limit. or at the very least that normal operating conditions at some times exceed that of which the part was designed.? otherwise, THEORETICALLY the part could never fail.?

about the build, i've got the RM springs and retainers, so i dont want to break a valve and place the blame because im a dumb *** trying to save a few bucks.

 

honestly i think a fatigue calculation would be far from the scope of most anything a person could do by themselves, without tons of knowledge and a lot of computing power.


you can look into something, but think of it this way:
say 2500 rpm for an hour a day, 2 cam cycles per crank revolution, 1 valve opening per cam cycle, 365 days a year, across 10 years...thats 1,095,000,000 valve openings... over a billion cycles, and possibly an underestimate. Honda designed them for an "infinite-life". the warranty is just always there to cover acccidents or processing errors.
the above should be the right number for my estimate...i hope.


if youre concerned, then just buy a new set. buying used parts is a gamble, but trying to reason yourself with a model you probably, nor anyone, could handle would be a big mistake.


Modified by dfoxengr at 9:30 PM 3/20/2007

 

oh man, now im thinking some crazy stuff. i gotta have a couple minutes to gather my thoughts.

 

take them to a machine shop
have them checked out and if they are good then go for it

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Don Lackey &raquo;</TD></TR><TR><TD CLASS="quote">Looks like the "Don's" are the only "engineers" chiming in so far. LOL.</TD></TR></TABLE>

I'll chime in if you want but Don has said what needs to be said.

The used parts people use now have more and more miles on them. We aren't talking wine here. Rods, valves and rockers are the most reused part in an engine. Then we hear why did my rod break, or valve drop, or why do I have uneven lobe wear? What about how many times the engine went to 9,500 rpm or higher.

Nothing is too good for my engine as long as it doesn't cost too much.

 

sorry i got all into it. i was on the supertech site yesterday and they talk about doing finite element analysis, and we were talking about fatigue defects in class today. then i was looking at my valves when i got home. the question had to come out.

 

thats great to think about stuff like that however, my classes make me do the same everyday.

 

eat sleep breath engineering, its the only way to get out with a degree.