Practical Engine Building: Step 9: Long Block Assembly
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Step 9: Long Block Assembly
04.36
| 00:00 | - Once the crankshaft and pistons are fitted to the block, we can move onto to assembling the long block, which involves fitting the cylinder head, or cylinder heads, oil pump, crank seals, sump, timing chain, or timing belt, and front covers. |
| 00:14 | We'd normally want to start by fitting new oil seals to the rear main and front cover assembly, and you can see how this should be done in the practical engine building skills section of the course. |
| 00:26 | Some rear main seals will locate in their own separate housing which bolts to the block, while in some cases the rear main seal will be installed directly into the block after the block is assembled, such is the case with a Subaru engine. |
| 00:41 | Before we fit the oil pump we want to disassemble the pump and fill it with assembly lubricant. |
| 00:47 | This is known as priming the oil pump and it's essential to ensure that the engine can quickly gain oil pressure when it's cranked over for the first time. |
| 00:56 | When it comes to fitting components such as the sump, rear main seal, and the oil pump housing or front cover assembly, often these components will be sealed with a silicon sealant, and this is an area where it's easy to end up with an oil leak if you're not careful. |
| 01:12 | We detail the correct approach to sealing these sorts of components and working with liquid sealant in the practical engine building skills section of the course. |
| 01:22 | Next we can fit the cylinder heads, but before we can do this, there's a little prep work that's required on the block. |
| 01:29 | We want to begin by making sure the crankshaft is rotated until the piston for number one cylinder is located just below TDC. |
| 01:36 | When we locate the pistons slightly away from TDC like this while we're bolting the head down, it helps ensure that we don't risk bending valves while the cams or valve train are being installed and timed. |
| 01:49 | The head gasket seal requires the mating surface of both the block and the cylinder head to be perfectly clean, so before installing the head gasket, I'll use a product such as brake clean and a clean rag to wipe down both surfaces and remove any last oil or dirt. |
| 02:05 | We can now install the head gasket, making sure that we have the orientation correct, and it's located correctly over the dowels on the engine block. |
| 02:15 | If you're using a head stud kit, this is the time to install the head studs into the engine block. |
| 02:21 | Any fastener that you install into a threaded hole in the block, should install smoothly by hand. |
| 02:27 | If you need to apply excessive force then it may indicate the thread in the block or on the fastener is damaged. |
| 02:33 | In this case you should stop and address the problem. |
| 02:37 | Studs don't need to be installed with a thread locking compound and they also don't need to be tightened excessively. |
| 02:44 | All we want to do is screw the stud into the block until it bottoms out, and is just a little bit beyond hand tight. |
| 02:51 | Now we can lower the head into place over the studs, ensuring that the head is lowered squarely onto the engine block. |
| 02:58 | Once it's correctly located over the dowels and the block, the washers and nuts can be installed, and the head can be torqued into place. |
| 03:06 | If you're dealing with aftermarket head studs, this often can get tricky as there'll be little information other than the final torque seal. |
| 03:14 | We also need to torque the head down in stages and torque the fasteners in the right order so that the head is clamped down evenly and achieves the best possible seal. |
| 03:25 | If the stud manufacturer doesn't provide an order to torque the studs in, then I follow those used by the OE manufacturer, which might look something like this. |
| 03:35 | The torquing process will normally start in the middle of the head and then gradually move out towards each end. |
| 03:42 | If you're using factory head bolts, then you'll want to use the factory torque specifications and stages but with aftermarket studs, you may only have the final torque value. |
| 03:52 | In this case I'll torque the stud in the three equal stages. |
| 03:56 | For example if the final torque is 90 foot pounds, I'd torque the studs initially to 30 foot pound, followed by a second stage of 60 foot pound, and then finally a third stage to 90 foot pound. |
| 04:10 | The last aspect we will need to consider is fitting the timing chain or timing belt and correctly timing the engine. |
| 04:18 | This is an area where we need to refer to the workshop manual to find out what the timing marks are, how to align them, and what order we need to fit our components in. |
| 04:29 | At this point our long block assembly should be complete. |
