Ideally, you should buy all of the rebuild parts before you start the project--forgetting to buy a an important part could just hold up the entire assembly and/or machining process. Unfortunately, in order to get the correct bearing sizes (assuming that the con rods, crank, and main journals are okay and don't require any machining), you have to pull the oil pan off to get the markings. Plan ahead and make things easier on yourself.
If this is your first time rebuilding a Toyota engine and you just tried ordering the regular-sized con rod and main bearings, your parts person prob'ly gave you a hard time about looking at the markings on the engine. Toyota took into account the possibility of irregularities when the block, crank, and con rod caps are machined. So, they painstakingly measured everything and accordingly stamped or marked the crankshaft, block skirt, and con rod caps. The engine assembly line used these markings to pick the perfectly-sized bearings to ensure uniform clearances for the critical parts.
NOTE: These markings will only work if and only if the engine's never had any machine work done to it. If you think the crank's been ground down to use oversized bearings, have the machine shop check it for you. If you place the normal-sized bearings on a machined crank, it'll rattle all over the place and eventually grenade! But, you're gonna check the clearances during assembly, right? =)
Where to Find the Markings:
How to Use the Markings to Select a Main Crank Bearing
| Cylinder Block # | 1 | 2 | 3 | 1 | 2 | 3 | 1 | 2 | 3 |
| Crankshaft # | 0 | 0 | 0 | 1 | 1 | 1 | 2 | 2 | 2 |
| Main Bearing # | 1 | 2 | 3 | 2 | 3 | 4 | 3 | 4 | 5 |
There are five ( 5 ) different main bearings. If you use the main bearing table above, you may notice that all you have to do is add the corresponding clearance values on the block and crank to get the main bearing size. For example, for main bearing journal # 2, the block is marked "1" and the crank is marked "3," the OEM main bearing will be a "4."
There are three ( 3 ) different con rod bearing sizes. For the con rod bearings, just use the numbers on the con rod caps. That's all there is to it!