head torque
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Joined: Dec 1969
Posts: 27,725
From: Little Rock, AR
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Joined: Aug 2007
Posts: 86
From: palm harbor fl
I don't have a torque angle meter,just a torque wrench and you should be able to just use the wrench to achieve the proper clamping force for these bolts.I did buy replacment bolts from rock auto and if I need to I will get the angle meter but I have spent an awful lot of money already just to fix another lame mechanics screw up.I actually broke a 1/2 in. drive 1/2 in. socket trying to get the middle row of head bolts loose,the lower short bolts were not even close to as tight even though there is only 13 degrees less angle.
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Registered User
Joined: Aug 2007
Posts: 86
From: palm harbor fl
while I'm on this subject is the sealant on the bolts all I need, and should I replace the o-rings on my injectors on the fuel rail side if I haven't removed them from the rail (I was replacing the ones for the intake).
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Joined: Nov 1998
Posts: 71,094
From: Hell was full so they sent me to NJ
Read this:
http://www.enginebuildermag.com/Arti..._bolt_use.aspx
http://www.enginebuildermag.com/Arti..._bolt_use.aspx
Torque-To-Yield
Torque-To-Yield (TTY) is a term that you should be familiar with because it describes a type of head bolt that is used on many late model engines. Unlike ordinary head bolts, TTY head bolts are designed to deform - but do it in a controlled way. Like a standard head bolt, a TTY bolt will stretch and spring back up to its yield point. But once the yield point is passed, the bolt becomes permanently stretched and does not return to its original length. Because of this, TTY bolts should not be reused.
Why intentionally stretch the head bolts? Engineers discovered they can get much more even clamping on the head gasket if all the bolts are evenly loaded. Since variations in friction between bolts always causes some uneven loading, stretching the bolts guarantees all the bolts will exert the same clamping force regardless of the torque reading on the wrench. The result is improved cylinder sealing, longer head gasket durability and less cylinder bore distortion (for reduced blowby and more power).
TTY head bolts are typically used on engines with aluminum cylinder heads (where there is a lot of thermal expansion) and with multi-layer steel (MLS) head gaskets. MLS head gaskets are very stiff gaskets with much less compressibility than standard soft-faced composition head gaskets. On the other hand, MLS head gaskets are almost bullet-proof and produce much less bore distortion than other types of head gaskets because they require less clamping force. But to seal properly, MLS head gaskets require very smooth (almost polished), flat surfaces on the head and block. This, in turn, requires very precise and even clamping loads by the head bolts. That's why TTY head bolts are used in these engines.
How can you tell TTY head bolts from ordinary head bolts? TTY head bolts are typically longer and narrower than standard head bolts. Factory service manuals will tell you which applications use TTY bolts, and you can often tell from the head bolt tightening procedure if the bolts are TTY or standard. TTY bolts typically have an angle tightening specification rather than a specific torque value (which requires using an angle gauge when tightening the bolts).
The torque procedure for tightening a TTY head bolt involves tightening it until a certain torque reading is reached. Then the bolt is given an additional turn to a specified angle (say an additional 45 to 90 degrees) to load the bolt beyond its yield point for maximum clamping pressure.
Torque-To-Yield (TTY) is a term that you should be familiar with because it describes a type of head bolt that is used on many late model engines. Unlike ordinary head bolts, TTY head bolts are designed to deform - but do it in a controlled way. Like a standard head bolt, a TTY bolt will stretch and spring back up to its yield point. But once the yield point is passed, the bolt becomes permanently stretched and does not return to its original length. Because of this, TTY bolts should not be reused.
Why intentionally stretch the head bolts? Engineers discovered they can get much more even clamping on the head gasket if all the bolts are evenly loaded. Since variations in friction between bolts always causes some uneven loading, stretching the bolts guarantees all the bolts will exert the same clamping force regardless of the torque reading on the wrench. The result is improved cylinder sealing, longer head gasket durability and less cylinder bore distortion (for reduced blowby and more power).
TTY head bolts are typically used on engines with aluminum cylinder heads (where there is a lot of thermal expansion) and with multi-layer steel (MLS) head gaskets. MLS head gaskets are very stiff gaskets with much less compressibility than standard soft-faced composition head gaskets. On the other hand, MLS head gaskets are almost bullet-proof and produce much less bore distortion than other types of head gaskets because they require less clamping force. But to seal properly, MLS head gaskets require very smooth (almost polished), flat surfaces on the head and block. This, in turn, requires very precise and even clamping loads by the head bolts. That's why TTY head bolts are used in these engines.
How can you tell TTY head bolts from ordinary head bolts? TTY head bolts are typically longer and narrower than standard head bolts. Factory service manuals will tell you which applications use TTY bolts, and you can often tell from the head bolt tightening procedure if the bolts are TTY or standard. TTY bolts typically have an angle tightening specification rather than a specific torque value (which requires using an angle gauge when tightening the bolts).
The torque procedure for tightening a TTY head bolt involves tightening it until a certain torque reading is reached. Then the bolt is given an additional turn to a specified angle (say an additional 45 to 90 degrees) to load the bolt beyond its yield point for maximum clamping pressure.
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