The Ford Barn - View Single Post - The Terry Burtz 5 main bearing engine blocks are back on track.

Terry Burtz, Calif · 06-02-2022, 05:24 PM

The following is from section 7 of the "Builders Guide" in regards to head torque.

Head Torque

Head and cylinder block cracks between the stud holes and the water jacket at the center of the engine are caused by engine builders that use a clad head gasket and start in the center of the head and apply torque in large increments.

Apply head torque in increments no larger than 10 lb-ft. Larger torque increments can crack the head or cylinder block at the center, especially when using a clad head gasket with a soft core that has a lot of deflection during the application of torque. The Best 509C (clad) gasket compresses from 0.080 to 0.052 inches during the application of torque, and the Best 509G (graphite) compresses from 0.058 to 0.055 inches during the application of torque.

Instead of torquing in a spiral from the center of the head outwards, there is less chance of cracking a head if you start at the rear and work forward.

Cast iron heads need no more than 55 lb-ft of torque. Torque for aluminum heads is dependent on the thickness of the head because aluminum expands more than twice what cast iron expands for the same temperature change and you need to ask your head supplier for a recommended torque value.

06-02-2022, 05:24 PM	#512
Terry Burtz, Calif Senior Member Join Date: May 2010 Location: Campbell,CA, USA Posts: 319	Re: The Terry Burtz 5 main bearing engine blocks are back on track. The following is from section 7 of the "Builders Guide" in regards to head torque. Head Torque Head and cylinder block cracks between the stud holes and the water jacket at the center of the engine are caused by engine builders that use a clad head gasket and start in the center of the head and apply torque in large increments. Apply head torque in increments no larger than 10 lb-ft. Larger torque increments can crack the head or cylinder block at the center, especially when using a clad head gasket with a soft core that has a lot of deflection during the application of torque. The Best 509C (clad) gasket compresses from 0.080 to 0.052 inches during the application of torque, and the Best 509G (graphite) compresses from 0.058 to 0.055 inches during the application of torque. Instead of torquing in a spiral from the center of the head outwards, there is less chance of cracking a head if you start at the rear and work forward. Cast iron heads need no more than 55 lb-ft of torque. Torque for aluminum heads is dependent on the thickness of the head because aluminum expands more than twice what cast iron expands for the same temperature change and you need to ask your head supplier for a recommended torque value.