hey i talked to the machine shop doing my heads and he insists he uses his valve guides and stem seals i already have http://www.conceptzperformance.com/...ar_Type=300&UID=20120803173023101.166.134.185 and ferrea stem seals as well but he says his will work way better??? should i be worried
Did they say what valve guides he intends to use? Sounds to me like they are going to use the stock guides and new stem seals.
nothing wrong with stock valve guides . I chose them over bronze but with ferrea seals (which also isn't needed on most engines)
This sounds odd to me, he says his parts will work "way" better, wtf has he parts from Nasa ? It is not like you have crap parts, I believe bronze guides are a little more difficult to work with then stock, I can only think he is trying to make life easy for himself and or sell some parts. Depending how far into the job you are and how much invested would determine what I would do, firstly I would insist my parts were used unless a satisfactory answer was given, if unexplained resistance or umbrage is met I would lean to pulling the job. If this is the first and only issue it would be difficult to do so, but if there are other issues surrounding progress I would lean towards getting a quit price and starting again else where That is just me, experience says to accept no BS, zero tolerance, or that is what you will get. Hopefully this answer will encourage you to stick to your guns, remember he is to provide you a service, if the jobs turns into something to serve him it is all over IMO.
They are varying opinions on that, bronze is porous and will hold an oil film better, they apparently transfer heat from valve to head better as well. I believe one of the problems are they need to be machined to size to fit and are softer, so fitting and getting the job done is harder.
Used for race applications where the motor gets pulled down more frequently. They can be machined to tighter tolerances, and bronze is a softer metal than steel. This means it will seal better but wear quicker. Also, bronze reduces the friction of the valve stem to guide interface. pointless on a street engine. But thats just my opinion
So a iron piston is better than an alloy one ? If fitted correctly bronze will last longer and perform better, correctly is the catch. Is it required ? on a stock OEM engine no, is it useful on a higher spec engine to assist in moving heat from the valve and other benefits, yes. The point is the customer made a decision about his build and the workshop wants to change that, unless they can supply good reason, I would stick to my preference. We all go about our projects in different ways, why ? because its our project and we enjoy doing it our way. There are benefits with bronze guides and there can be a small extra cost in fitting, if the shop is not confident in doing it, find another shop.
never said not to use it in any of my posts. And agree if he already has the parts ..use them but people buy performance parts because they are told they are better/benefits but not always suit their application . In my application I should have bronze ,but eliminating a possible premature wearing part of my engine. we'll agree to disagree about the softer material wearing out sooner.
Don't think getting the job done is harder. The benefit to fitting bronze valve guides is in the lubricating properties, the trade off is longevity. The improvement in performance will be barely discernible compared to an identical engine running standard guides however the bronze WILL wear faster and require servicing sooner. The customer has made his decision based on what he read on the Internet. I should know, I did the same In hindsight I should have listened to my good and experienced engine builder. I would sooner take the advice of someone who builds engines everyday and has a vested interest in the outcome of the build than someone trying to sell me parts.
Yes there are varying opinions on that. Bronze guides will require tighter clearnaces to make good on there benfits and out last iron guides. If you cannot build to a level to achieve the benefits of a material you are better off not using it. Other wise we would be using iron bushes in our small ends I guess, but these are a lot easier to deal with than 24 guides.
Yes there are varying opinions on the subject. But they mean little to the OP. Fitting bronze guides is more work then refinishing fitted ones and will last longer with a tighter clerance and the overall increase in accuracy of maching will make the job more detailed as simple as that. I beleave they will last longer and so do many far more experienced people, but again there are varying opinions on this.
