What torque settings should head bolts be tightening to?
If an engine produces 1,500 pounds of pressure and the cylinder head has 8 bolts, then each bolt must be tightened to 187 foot-pounds of torque to secure the cylinder head to the block.
What is the cylinder head bolt tightening sequence?
Normally you would tighten conventional head bolts in a crisscross pattern in three steps, to one-third, two-thirds, and then to the final torque. Next, turn all the bolts, again in sequence, by 90 degrees. Then turn them all yet again, in sequence, a final 90 degrees.
Can you over torque head bolts?
Overtightening head bolts can damage the block threads, yield the bolts, and in extreme cases crack the cylinder head. Some heads are actually fitted using torque to yield (sometimes called stretch bolts), where the bolts must be replaced after use, or they loose some of their strength.
What happens if you reuse a torque to yield bolt?
Torque-to-yield (TTY) head bolts are designed to stretch when used. Once stretched, they are not as strong as before. Consequently, they cannot provide the same amount of clamping force and may break or shear off if reused.
What happens if you dont torque head bolts?
If the head isn’t torqued down properly, then the most likely failure is of the head gasket, which could lead to loss of compression, the mixing of oil and coolant, exhaust gases getting into the oil ways or cooling channels, erosion of the cylinder head, overheating and warping of the cylinder head.
Should you lubricate cylinder head bolts?
you should always lube anything that is going to be torqued or else you won’t get an accurate reading…you want to be measuring the torque without any friction interfering with the reading.
What is the final step when torquing down head bolts?
The final step is rechecking the torques of all head bolts after a few hours. Sometimes a head and block will stretch as will the bolts holding them together. If you are really finicky you can run the engine up to temperature and let it cool completely and then recheck the torque.