Big Block Chevrolet Head Bolt Torque Sequence
Another EZ Read reference. This is the Head Bolt Torque Sequence (Pattern) for the Mark IV Big Blocks, Rat Motors or what ever you might lovingly call the motor. I am an old timer and had a 1969 SS 396 that subsequently got a 427. I am a fan of this motor, they make good power with only a little work and not much sounds as good a a uncorked BBC at the drags. I have a ZL1 powered Cobra as no reason to put a lump of Ford Iron into one of those cars. Check that out here - Herb Adams VSE Cobra.
Note : this does not include the extra bolt holes for some aluminum blocks that is in the intake port. These are installed from inside the valley chamber, and typically are a short stud.
Big Block Chevy Head Bolt Torque SpecificationsLong Head Bolts 75 - 80 Ft/Lbs
Short Head Bolts 65 - 68 Ft/Lbs
I would also add make sure you torque the bolts in steps. Do a first round hand tight, second round at 50% torque (OK, let's just say 35 Ft/Lbs) then final round at specs.
For Head Studs or aftermarket bolts CHECK YOUR INSTRUCTIONS, BBC studs are available in a ton of different styles depending on heads and stud diameter (7/16" and 1/2").
For what ever you use make sure the threads in the block are clean. It doesn't hurt to run a tap on every bolt hole (unless for some reason you have a thread insert in them) to ensure proper torque. For some blocks you will have the bolt holes drilled through to the water jacket. Use a good sealer on the threads (ARP, Permatex) something specific for bolts. If you have blind bolt hole use the recommend ARP lubricants on bolts or studs.