Main cap bolt 396 454 4 bolt inner and outer 110 ft lbs. These specs are for stock type bolts with light engine oil applied to the threads and the underside of the bolt head.
Damage Alert How To Avoid Pulling Threads Or Killing Head Bolts
Header bolt torque aluminum heads. Discussion starter1mar 10 2005. Hey i thought i would share a recent experience and some tidbits that i searchedalmostendlessly for. I have an aluminum head zz4 in my 68 and recently lost a header bolt. Aluminum has a higher coefficient of expansion than cast iron. I use the small head stainless arp header bolts and because of the configuration. Some people do only 1 or 2 steps to reach the final torque.
For head studs or aftermarket bolts check your instructions sbc studs are available in a ton of different styles depending on heads and stud diameters. Cylinder head bolts short. Jump to latest follow. Main cap bolt 396 427 2 bolt 95 ft lbs. For example i got the arp head studs and only torqued my heads down to 115 lbsft with moly lube. You need to follow the instructions that came with the bolts.
Moly and other lubes offer reduced friction and increased bolt tension which will affect the torque figure. If there are gaps or warpage have a machine shop mill the mating surface flat. On each head bolt to make sure none have been missed and that the bolts are retaining torque normally. Use a straight edge and check for flat. Screw in rocker arm studs. Tightening header bolts into aluminum heads.
Yes your torque specs will be different with aluminum heads than cast. Cylinder head bolts long. Intake manifold bolts cast iron head. If a bolt is not coming up to normal torque or is not holding a reading it means trouble. It will take only a modest amount of torque to seal the header anyway. I blew an exhaust gasket and decided to fix the whole enchilada correctly.
Gallery of Header Bolt Torque Aluminum Heads
