Parts to Help Reduce Repair Costs
The FEL-PRO Engine$aver Hardware line is a collection of “problem solvers” that
provide cost-saving alternatives to engine component replacement. They bring engine
components back to proper performance, at a fraction of their replacement cost.
Engine$aver Hardware Is Cost Efficiency Without Compromise
Understanding Torque-to-Yield Head Bolts
Although Torque-to-Yield (T-T-Y) head bolts are
becoming more common, some people still don’t
fully understand how they work.
Bolts on T-T-Y applications are tightened to their
yield point, creating a more even clamping force
over the entire area of the gasket.
During engine assembly at the factory, precision
machines tighten the bolts so they are just in the
“yield zone.” Technicians making repairs in the field
do not have access to this type of equipment.
Engineers have found that by tightening head bolts
to specified torque and then tightening them an
additional partial turn, technicians can reach the
yield zone.
Fel-Pro
®
engineers suggest technicians use a gauge such as the inexpensive Fel-Pro
®
Torque-to-Angle Indicator (part number TRQ-1). It fits easily on the 1/2” drive of a torque
wrench and eliminates uncertainty about the additional torquing required for T-T-Y head bolts.
Are T-T-Y Head Bolts Reusable?
The torque-to-yield procedure stretches the bolts into their elastic range. On some
engines, this stretching approaches the bolts’ elastic limit and the bolts are permanently
stretched. If these bolts are removed and reused, it is likely that either the head gasket
will fail due to false torque readings or that the bolts may break. Each engine manufacturer
offers guidelines as to whether torque-to-yield head bolts are reusable. Some guidelines
allow limited reuse, while others recommend you never reuse the bolts. Since technicians
may not know how many times a T-T-Y bolt has been removed and reinstalled, we recommend
never reusing a T-T-Y head bolt.
FEL-PRO
®
Engine$aver
®
HARDWAREFEL-PRO
®
T-T-Y HEAD BOLTS
NOTE: There is no way to
visually tell if a bolt is the
Torque-to-Yield design –
the only way to tell is by
its torque specifications.
Cylinder Head Bolts
Help avoid the risks that go with reuse of
head bolts on torque-to-yield applications.
Torque-to-Angle Indicator TRQ-1
Assures that proper installation procedures
are followed when using torque-to-angle
cylinder head bolts.
HeadSaver
®
Spacer Shims
Compensates for excess metal removed
during machining operations, so you don’t
have to replace costly cylinder heads.
Cylinder Head Dowel Pins
Assure proper gasket and casting alignment
for an accurate seal and correct head-to-
block assembly.
