Re: 1991 V135 - Project Engine
9/17 -
Balancing - Pistons and Rods went in for balancing today. The crank and flywheel are being left as is but there is some question as to how it is balanced, internal or external. The flywheel appears to not have any balancing adjustments done to it nor does the crank therefore the weight of the pistons and rods may be critical.
Here's an aritical that describes the issue:
http://www.enginebuildermag.com/Article/48121/understanding_crankshaft_balancing.aspx
Chasing Threads - Chasing threads in aluminum is not difficult or disasterous in any way.
The first trick of the trade is to own a thread gauge and a resonably accurate caliper. It's usually easiest to measure the threads per inch on the fastener that was originally used in the thread hole. The diameter is determined by the diameter of the fastener stock and not by the wrench that you use to remove it. I'm using the term fastener because the difference between 5/16 NPT (National Pipe Thread) and 5/16 NC (National Coarse) or NF (National Fine) is pretty dramatic. NC and NF are identical diameter stock but the threads per inch change. NPT is measured by the inside diameter of the stock and it uses a tapered thread for sealing puposes.
The second trick of the trade is to use a lubricant just as if you were cutting new threads. You should always use a lubricant whenever cutting threads no matter what material is being worked with. I use 2 cycle oil since it is a light weight oil and is easily disolved with gasoline. This is a good choice for a lubricant when working with any two cycle engine since any oil that is not cleaned out during the final block cleaning process can easily be digested by the engine. Please note, this is not an excuse to not worry about cleaning it all out. There will likely be metal particles left behind that will damage even the best built engines. Clean, clean, clean.
The third trick of the trade is to be precise. Start the tap by hand without a leverage device installed on the tap. You should be able to run it in by hand feeling only light resistance as you remove the corrosion and sealing materials that were left behind. When you remove the tap, be careful not to rock it from side to side as it exits the thread as this could damage the all important starting threads.
The fourth and final trick is to clear the hole before you try running a fastner into it. Flush it with liberal amounts of solvent and blow it out with compressed air until you are satisfied that all foriegn materials have been removed. Again, clean, clean, clean.
I don't care if you think chasing threads is wrong or not. I want my torque specs to be as accurate as possible and this is the only way that I know to accomplish that.
Port and Starboard - If you mix them up just remember that the marine industry is the only industry that uses them. I will not be using them in any further context of this thread unless it is absolutely necessary. We're building an engine here not navigating the ocean. Technically, the port side (larboard) is the side that the vessel where cargo is taken on in port and the starboard side is the side that the vessel is steered from. History wise it wasn't until the mid 1800's that it started to become standardized as meaning left (p) and right (s) when facing the bow.
I've been on a lot of ships and in one year alone logged over 100,000 open ocean nm. I've been on ships that take cargo on to port or starboard and many that steer from dead center.
On this engine the GLM pistons are marked "UP" so as long as up is up and down is down and you don't need to worry if port is left or right, wrong. What you need to worry about is if the pistons are correctly marked. This engines pistons have a boost port and the orientation of the piston must be aligned so that the boost port is correctly aligned in the cylinder. Just make sure that 3 align correctly on one side and 3 align correctly on the other before you send them off for machine work.
