The break away torque is higher than the prevailing torque . Newer torque specs often call for a specific torque setting ,then a rotation further of a set number of degrees,say 1/2 turn. This is especially true of "Torque to yield" fasteners. Actually the head fasteners should be replaced. Luckily these old farm implement motors we run aren't real fussy .The main thing is to pull them up evenly to establish a tight seal and even pressur to minimize cylinder distortion. To tell the truth I haven't retorqued any of the top ends I've done for my self ,and I'm doing just fine ,thanks. If you are retorqueing to seal a leaky joint ,do yourself a favor and replace the gasket. Never can tell about POs . Sometimes you are glad to find they DIDN'T have a torque wrench ;-) Tom Bowes wrote:
The theory is simply to make sure that fastener moves during the torquing process, in order to get a more accurate result. Does it really
matter on a Guzzi cylinder head that is receiving its 1000 mile retorque? Not one iota. The Guzzi cylinder head gaskets are soft enough that something would have to be seriously askew to NOT break the fasteners loose. When I recently checked the torque on my G-5, which had
new head gaskets installed by the previous owner, it only took about ten
foot-pounds to get things moving. That's pretty loose considering that they started 2000 miles before at nearly 30 ft-lbs.
Guzzi-@aol.com wrote:
Never could figure out why you would loosen heads to tighten them,what is the THEROY behind this.Mark