You measure them, look for pulled threads. Like I said earlier, I torqued them to 70 ft. lbs., which they will handle easily. It's N/A, not a 500 hp. turbo build....
This car doesn't use TTY bolts. All the cars I've worked on that do, use a different torque sequence. It will be something like 20 ft. lbs., 35 ft. lbs., then 90 degrees. The 90 degree step sets them to their yield point. None of the bolts are torqued to exactly the same ft. lbs. by turning them "X" degrees, they're all gonna be slightly different.
Also, if you pay attention when your torquing the bolts down, you'll notice if one is weak, it'll feel different. It's hard to explain, but you can feel the difference between a solid bolt, and one that is twisting, or stripping out the hole. Guess it just comes down to experience....
By the way, these have to be the heaviest bolts I've ever seen for being torqued to such a low spec. 58 ft. lbs. isn't very much. Most vehicles use at least 65 ft. lbs., and some use much more. These bolts are pretty thick, and short. If you twist or break one, you've either way over torqued it(bye bye head), or the motor has been extremely over heated(bye bye motor).
Most mechanics I know(even the well educated, ASE Certified) reuse head bolts all the time. There's only certain vehicles it shouldn't be done on. I think Ford's Power Stroke uses close to 200 ft. lbs. on the head bolts, and shouldn't be reused. They have a CR of around 30:1, and most of the programmers bump the boost up to 28+ psi. That's a lot of pressure on those bolts.
I think there's a few specific reason's people have problem's with hg's they put on.
1. They don't clean out the bolt holes in the block. If there is any water, oil, or trash in there, it will give you an inaccurate torque, and the bolt won't seat correctly.
2. They don't follow the correct tightening sequence. You start from the middle, and work your way out to the ends.
3. They don't know how to use a torque wrench correctly. You have to reach the correct torque while the bolt is moving. This means you have to plan that last turn so that you don't run out of room before you reach the correct ft. lbs. It takes more torque to start the bolt moving then it does to continue turning it.
4. They try to do it cheap, and don't get the head checked and milled. If it overheated, the head warped. Period. Take it to the machine shop, and get it fixed. You can check it if you want, but if you don't have a machinists straight edge, you won't get an accurate reading. No, the carpenter's level you have leaning in the corner won't work. You MUST use the right tools for the right job.
This car doesn't use TTY bolts. All the cars I've worked on that do, use a different torque sequence. It will be something like 20 ft. lbs., 35 ft. lbs., then 90 degrees. The 90 degree step sets them to their yield point. None of the bolts are torqued to exactly the same ft. lbs. by turning them "X" degrees, they're all gonna be slightly different.
Also, if you pay attention when your torquing the bolts down, you'll notice if one is weak, it'll feel different. It's hard to explain, but you can feel the difference between a solid bolt, and one that is twisting, or stripping out the hole. Guess it just comes down to experience....
By the way, these have to be the heaviest bolts I've ever seen for being torqued to such a low spec. 58 ft. lbs. isn't very much. Most vehicles use at least 65 ft. lbs., and some use much more. These bolts are pretty thick, and short. If you twist or break one, you've either way over torqued it(bye bye head), or the motor has been extremely over heated(bye bye motor).
Most mechanics I know(even the well educated, ASE Certified) reuse head bolts all the time. There's only certain vehicles it shouldn't be done on. I think Ford's Power Stroke uses close to 200 ft. lbs. on the head bolts, and shouldn't be reused. They have a CR of around 30:1, and most of the programmers bump the boost up to 28+ psi. That's a lot of pressure on those bolts.
I think there's a few specific reason's people have problem's with hg's they put on.
1. They don't clean out the bolt holes in the block. If there is any water, oil, or trash in there, it will give you an inaccurate torque, and the bolt won't seat correctly.
2. They don't follow the correct tightening sequence. You start from the middle, and work your way out to the ends.
3. They don't know how to use a torque wrench correctly. You have to reach the correct torque while the bolt is moving. This means you have to plan that last turn so that you don't run out of room before you reach the correct ft. lbs. It takes more torque to start the bolt moving then it does to continue turning it.
4. They try to do it cheap, and don't get the head checked and milled. If it overheated, the head warped. Period. Take it to the machine shop, and get it fixed. You can check it if you want, but if you don't have a machinists straight edge, you won't get an accurate reading. No, the carpenter's level you have leaning in the corner won't work. You MUST use the right tools for the right job.
