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By Sazerac
#19780
Hi All

So, I have been pondering this topic for a while. To make a link to the real world first, I remember about 20 years ago reading an article about the M1 tanks that had been built using bolts from Taiwan that had been improperly marked. In the end, to the tanks had to be completely disassembled and reassembled with proper bolts to ensure the battle worthiness.

I generally like the idea of **replacing** head bolts when doing heads. BUT, the recent bolts I have purchased from Porsche have been unmarked. That is they have not had any markings on them as to grade or manufacturer. I have used them, they seem to work (2 years and counting), but what do others think about this?
User avatar
By SeanR
#19786
I've replaced a good many of them and have not had any issues with them. I'd not think about it, especially since yours are installed and holding things together such as they are supposed to.
User avatar
By worf
#19816
When I turn the head bolts I set my torque wrench to display torque and angle simultaneously. As I turn in each bolt I watch the torque display so as to take note of the increase in torque as the bolt turns. If I were to ever see the torque on a bolt not increase as it turns I know that the bolt is stretching with no increase in clamping force. And that, to me, is a bad sign. It would cause me to throw that bolt away (and of course, to turn out all the other bolts and start over on that head.)

That's my plan, FWIW, for dealing with a material materials change in head bolts.
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