Blueprint 103 - Connecting Rods
Connecting rods are the crux of the engine. They're responsible for carrying the force of the explosions that occur in the combustion chamber and using it to turn the crankshaft. Oil clearance specifications of the "big end" and "small end" are crucial to maintaining consistent oil pressure. In this video we take 3 measurements: Rod Gap Rod Journal (also called Crank Pin) Diameters "Big End" Bore diameter Using the Journal diameters and the "Big End" Bores, you can calculate your oil clearances of each bearing. The process is illustrated here. Anyone rebuilding an engine who doesn't know its history should check all of these clearances whether or not they're re-using the rods. If the crank, bearings or connecting rods are going to be replaced, it's imperative that you measure the new parts as well to ensure they're in spec.
Blueprint 105 - Main Bearing Oil Clearances
In this episode we measure the bores for the crankshaft and calculate the oil clearances based off of information gathered in the previous video. If you subtract the diameter of the crankshaft from the bore diameter, you end up with your oil clearances. If this were an assembly with new parts, I would have also paid close attention to bearing measurements 45° off-centerline just to make sure the bearings aren't pinched. I would also have double-checked the clearances using Plastigage. But what I'm doing here is just getting baselines prior to machining. If you're doing a dry assembly like this, DO NOT ROTATE THE CRANKSHAFT. Without oil, there is nothing preventing it from being damaged.
Blueprint 101 - Using Micrometers, Calipers, & Bore Gauges
THESE MICROMETERS ARE PROPS. They're cheap, easy-to-read, and they were defective straight out of the box. They couldn't be calibrated. The graduated sleeve was seized up and rusted to the bodies of each one. They're also not accurate enough to measure taper or runout on a bearing journal which is necessary if you're rebuilding an engine. If you're going to rebuild an engine and you're not already familiar with these kinds of tools, this video is required material. None of your measurements mean anything if they're not accurate. I illustrate the calibration and use of 3 major tools needed for taking measurements, and a brief demonstration of how they work. These are by no means the ONLY ways to use or calibrate these tools. This is simply the method I will employ to measure parts in later videos so this instruction doesn't distract from their intended messages. Even if you're familiar with these tools, you may find something useful here, or even be able to correct me and my rusty skills. When I can afford a $1200 set of Micrometers, I'll re-make this video.
Blueprint 104 - The Crankshaft
It's important to know what you've got even before dealing with the machinist. If you want to inspect a crankshaft, this is how you do it. I detail the process of removing the crank and what to measure. All specifications in this video are illustrated with a 6-bolt 4g63 turbo block, but are all actually the same for 7-bolt engines with the exception of the rod widths.