TORQUE TIPS

Engine manufacturers supply head bolt torque values and tightening sequences - follow them exactly. In general, make sure your torque wrench is accurate, and starting from the center of the head and sequencing the bolt tightening out to its ends, torque the bolts to their maximum clamping load in 3- 5 steps. That is, snug all the bolts, then following the sequence order, tighten them first to 25% of the final torque value, then 50% of the final value, and then to 100%. The relative torque values at each percentage aren't so critical as building up to the final clamping load value in steps. For insurance, double- check the final torque reading on all head bolts.

Here's a quick low-buck tip from Keith for confirming if your torque wrench is accurately calibrated: get access to a torque wrench you know is calibrated, and then using socket adapters, join the head of your uncalibrated torque wrench to the head of the calibrated one. Pull the wrenches in opposite directions and compare the values. He prefers using torque wrenches with a dial indicator of torque value instead of a "click-type" torque wrench.

RE-TORQUE & REUSE?

According to Keith, he doesn't re-torque head bolts after installing a racing head gasket. This advice applies for non-copper gaskets. The Flatout guys have re-torquing comments on those below. Conventional thinking is that once fully assembled, a newly built race engine should be run up to full operating temperature, and then shut off and allowed to cool to room temperature. Next, following the installation order, each head bolt is broken loose and re-torqued to its maximum value. Dorton emphasizes that the modern race engine's valve train is so complex, that it is too time-consuming and impractical to undress / re-dress and readjust the valvetrain to get to the head bolts. He declares, "With the advent of new gasket materials and designs, we haven't found it necessary to re-torque head gaskets in years."

Dorton also has reused modern premium non-copper racing head gaskets because of their durability. He's found MLS (Multi-Layer Steel) head gaskets to be very durable and has re-used them when testing different sets of cylinder heads on the same block. The point is, you may fully assemble an engine and have a mechanical problem with the parts, and yet be able to reuse the head gasket at reassembly once the mechanicals are fixed or replaced. It shouldn't become a habit, but you can economize by judiciously reusing gaskets.

Angle-milling the heads, or other machining on the block, may produce a large gap (pointer) between the intake manifold mounting flange and the block's end rail. Trial-fit the parts with the intake port gaskets in place to see how large this gap is. A stock end rail gasket usually will not seal this effectively.

RTV silicone rubber is ideal for sealing this gap. Lay down a solid bead of it along the end rail before assembly. Not too much, you don't want a stray blob of it to break off and fall into the lifter valley.

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