How to Install Head Bolts

If you have never installed head bolts, it is best to do your homework and arm yourself with the bolt torque and tightening order specs of the engine you're working on. Proper bolt lubrication, cleaning, and deburring, along with aluminum heads and washer placement, all help to make the engine work properly upon completion. There is no such thing as a quick-and-dirty job when it comes to head bolt installation: do it right or you'll have a problem on your hands.

Procedure:
1. Inspect each bolt to assure clean and undamaged threads. Use a wire brush to clear any foreign matter off the threads. Use the service manual to check proper bolt length for each location. If the head has been resurfaced, bolts may be slightly too long and bottom out before exerting the proper downward force on the head. In this case, use hardened steel washers to make up for lost head height.
2. Run a bottoming tap down each bolt hole to clear out any debris. Apply motor oil to all bolt threads and to the bottom of the bolt head. If the head is aluminum, use manufacturer-recommended hardened steel washers under each bolt head, chamfered-side up, lubricated. If the head has been resurfaced, you will have to use thicker washers to make up for lost head height to keep bolts from bottoming out. Make sure all surfaces on the head, washers and bolts are clean and burr-free.
3. Drop each bolt into its respective location and finger tighten. Use the service manual for bolt-tightening sequence. Use the beam-deflector torque wrench to tighten all bolts in 3 to 5 steps. The first step tightens all bolts in sequence to a percentage of full torque. Each subsequent step tightens all bolts in sequence to progressively higher torque specs until the final step sets the bolts to the rated final torque. Guesswork can warp the head or cause leakage and overheating.
4. Re-check torque on all bolts. If you missed one, this step will find it. Bolts are made to stretch somewhat, so the final torque check assures proper clamp force on the head. Read More »»

SBC Head Bolt Torque Specifications

In 1955, GM took the automotive world by storm with the introduction of the Chevrolet Small Block V8 Engine. The SBC was originally designed for the Corvette, but soon became the standard for GM muscle cars, modified Jeeps and hot-rods. The first-generation SBCs had a displacement of 265 cubic inches and delivered 180 horsepower. By 1957, the larger version was delivering an astonishing 283 hp--one horsepower for every cubic inch of displacement. As a result, the engine earned the evergreen nickname of "Mouse." To date, more than 90 million have been sold, mostly through GM's popular "Crate Engine" program.

Top Overhaul
To maintain peak performance between major overhauls, most muscle car, Jeep and hot-rod enthusiasts perform a regular "top overhaul" on the SBC engine. This is done by removing and dismantling the cylinder heads, scraping away excess carbon deposits from the top of the pistons and inside the cylinder head combustion chambers, refinishing and polishing inlet and exhaust ports, and finally refacing and lapping the mating faces between the valves and valve seats with grinding paste. The cylinder heads are then re-assembled and bolted back onto the engine block.
Cylinder Head Bolt Tightening Sequence
Standard SBC cast-iron cylinder heads must be tightened onto the engine block in the sequence specified by GM. Cylinder head gaskets are first coated on both sides with a special sealant. The bolts are then inserted and tightened by using moderate torque with a socket wrench. This is done by starting with the central bolt and working outward bolt-by-bolt on either side in the sequence specified in the GM engine manual. This method ensures full contact between the cylinder head gasket and mating faces. It also eliminates the possibility of cylinder-head warpage.
Cylinder Head Bolt Torque Specifications
An adjustable torque wrench fitted with a socket is used during the first torque sequence. The socket is placed over the cylinder-head bolts and tightened until the torque wrench "breaks" and cannot tighten further. This is done at an initial torque wrench setting of 35 to 40 pounds-feet, and by following the sequence laid down in the manual. The torque wrench is then set to between 60 and 70 pounds-feet and the bolts are torqued a second time in the specified sequence. As subsequent bolts are torqued to the higher setting, they relieve some of the pressure imposed on the previously tightened bolt. The bolts are then finally torqued down with the same setting of 60 to 70 pounds-feet to relieve any remaining cylinder head stress. This procedure also ensures that the bolts have been pulled down evenly. Read More »»

Remove Extremely Tight Bolts

Bolts that have been in place for a long time often become so rusted they cannot easily be loosened with a wrench or socket. Exposure to moisture makes them even rustier. Trying to force a bolt will likely just damage the head of the bolt, making it even harder to remove. Trying to force off a rusted bolt can also injure a worker's hands, especially if the socket or wrench slips. There are, however, effective and safe ways of loosening tight and rusted bolts.

Procedures:
1. Spray a commercial rust-removing solution or lubricant on and around the bolt, trying to cover as much of the bolt as possible. Wait a few minutes. Loosen the bolt, if possible, with a wrench.
2. Use a propane torch to heat the top of the bolt if it remains stuck. Before applay a flame, though, wipe up or dry off with a rag any remaining rust-removing solution or penetrating oil around the bolt. Flames and petroleum-based solvents aren't a good combination. Heating the top will cause the entire bolt to expand. It should take about a minute.
3. Place a wrench back on top of the bolt and turn counterclockwise. If the bolt becomes too rounded for the wrench to fit properly, tighten a pair of lock pliers onto the head of the bolt. Once it is locked into place, push or pull the pliers counterclockwise to loosen the bolt, using as much force as necessary. If the bolt still will not turn, tap the pliers with a hammer counterclockwise until it loosens.
4. Put a socket onto the head of the bolt if it still will not loosen and then place a short piece of pipe over the socket handle. This piece of pipe is often called either a buster bar or a cheater bar. Grab hold of the buster bar and push or pull counterclockwise until the bolt loosens. Do not use too much force or the socket might break.
5. Cut off the top of the bolt with a hacksaw if it still will not loosen. A cold chisel or reciprocating saw may be used instead. Another way to break the bolt is to use a nut splitter. It will break the nut without damaging the threads of the bolt.
6. Remove the rest of the bolt with a screw extractor. Take the drill bit that came with the screw extractor and place it in a drill. Then drill a hole through the center of the bolt. Place the screw extractor in the recently drilled hole and turn counterclockwise until the bolt is removed. Read More »»