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 torque sequence for head bolts?
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 . Stretch bolts are tightened in a torque-plus-angle sequence.
How do you determine torque for tightening bolts?
DETERMINING TORQUE
The general equation for bolt load based on applied torque is T = KF i D b where K = torque coefficient . K is a function of the coefficients of friction and collar friction in the joint, and these are based on variables such as surface finish, coatings, and so on.
Do head bolts have to be torqued?
In most cases you don’t need to retorque head bolts or studs. If the bolts or studs aren’t tight you will lose compression or get coolant in your cylinders. You can use bolts or studs based on application, but studs tend to give more consistent torque values. Never reuse Torque-To-Yield (TTY) bolts.
Can you over tighten head bolts?
When you overtorque above 15% of recommended which in this case would be about 95 ft/lbs you basically turn the fastener into a rubber band. Some of the fasteners will stretch and you will have uneven torque. Add heat and pressure and head gasket blows and the head can even warp.
What happens if head bolts are not tight enough?
Another consequence of failing to torque the head bolts properly can be head warpage . Uneven loading created by unevenly tightened head bolts can distort the head. Over a period of time, this may cause the head to take a permanent set.
What is the torque of hand tight?
What torque value is hand tight? RE: Hand Tight Torque Be EXPLICIT about the torque limit: “ TIGHTEN to 4 ft-lbs of torque. NEVER USE MORE THAN 5 ft-lbs of torque! ” in your instructions.
How do you convert tension to torque?
The Torque/Tension Equation is a method used to estimate the torque/tension relationship in an assembly. T = (K D P)/12 can be used to developt a torque value that will achieve a certain tension or clamp load. T = Torque (ft. -lbs.)
How do I calculate torque?
To calculate load torque, multiply the force (F) by the distance away from the rotational axis , which is the radius of the pulley (r). If the mass of the load (blue box) is 20 Newtons, and the radius of the pulley is 5 cm away, then the required torque for the application is 20 N x 0.05 m = 1 Nm.
Do head studs add horsepower?
Exactly, headstuds are not defined by horsepower . From my understanding stock head bolts when re torqued can stand up to 40psi but anything past that you want to throw studs in it otherwise you’ll be blowing headgaskets.
Why do head bolts break?
Fatigue failure happens when the bolts have not been tightened properly, or have loosened up during its service life. If enough force is acting on the loosened joint during use of the product, bending stresses can weaken the fastener, eventually causing it to fail.
Should I reuse cylinder head bolts?
A head bolt should not be reused if the threads are galled or badly damaged . ... Chasing damaged head bolt threads with a die will clean up the threads but also remove material (metal) and undermine the head bolt’s ability to torque down and hold to specs.
Should head bolts be oiled?
Yes, you should lightly oil head bolts when you install them . You don’t want to have the bores full of oil or anything, but lightly lubricate the threads and heads. Torquing a bolt that size dry will give an inaccurate and insufficient torque because of the friction of the bolt head against the head surface.
What happens if you over tighten bolt?
Typically, an under torqued bolt will deform and be unable to provide as much clamping force as needed. An over torqued bolt will break .
What happens when you over tighten bolts?
Everyone who has ever worked with fasteners has accidentally messed one up at some point. One of the most damaging ways to do that is by over-tightening, or over torquing the fastener. This can result in stripping screws, snapping screw heads and damaging pre-tapped threading .
