bent valves

Aussie

Zoom-Zoom
That's what I asked before. How do you machine a bent valve? The only way I could think of would be to heat it up and press it into a die to straighten it, this would not be worth the trouble imo.
 

dc2GS-R

Super Moderator
Aussie said:
That's what I asked before. How do you machine a bent valve? The only way I could think of would be to heat it up and press it into a die to straighten it, this would not be worth the trouble imo.
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Plus, once it has been bent before, the material has surpassed elasticity and has yielded. This greatly reduces the tensile strength of the material. Just bending it back compromises it even more. The only way to really increase the material strength back up would be through case carburization, which would be highly unfeasible considering the cost of valves isn't too expensive.

In simple terms, they're trash. :lol:
 


jdmjim

nothing from nowhere
dc2GS-R said:
Plus, once it has been bent before, the material has surpassed elasticity and has yielded. This greatly reduces the tensile strength of the material. Just bending it back compromises it even more. The only way to really increase the material strength back up would be through case carburization, which would be highly unfeasible considering the cost of valves isn't too expensive.

In simple terms, they're trash. :lol:
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is that like when you keep bending something back and forth it breaks?
 

dc2GS-R

Super Moderator
jdmjim said:
is that like when you keep bending something back and forth it breaks?
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Pretty much. It gets weaker each time it's yielded (bent), whether it be the first time or the last.

Bending something within it's elastic properties does not effect the strength and the material will return to it's original form. Bend it passed elasticity, and it yields where it is permanently deformed and material strengths are reduced.

Think of stretching a spring. If you pull it a little and let go, it will spring back to it's original shape and retain it's spring. Pull it too far, and it never returns and will easily break. All materials have these properties, although over simplified in this case to get the point across.
 

Aussie

Zoom-Zoom
Yes and most valves are heat treated, this causes the bond to strengthen but because they are harder and bonded tighter it gives less room for flex and more room for breakage. Kind of like high speed steel bits, they're strong until you apply force on them the wrong way.
 
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mirrorimg

Well-Known Member
Probably got it when she hit 100 posts. She certainly did have her issues, but she's gone now, and I dont live in the past.
 

vonnyvegas

Finger Tapping With Fury!
I just recently dealt with the same problem of my timing belt breaking....I said F-it and put an engine in
 
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