If your drill press has a very low speed capability, or you have a vertical mill, a simple jig can be fabricated with an offset hole for mounting a ball bearing to orbit the big oil drain back hole in the center and a bit of a pan to capture the grinding compound as it falls out of the system. In less than an hour you can produce a superb finish on two irons. Also you can recover nearly all of the compound. The irons are gas Nitrided for longer wear about .005" deep. But early irons were not. They would still go over 100,000 miles. Plus, the irons so lapped will hold an oil film better than a stock iron, and seal better than a stock iron.
In cases where the iron is slightly warped, you can have it ground flat on a head machine on both sides. Then lap it to kill off the tooling marks and produce that great finish.
Keep in mind that the engine (stack) is getting a bit shorter each time you do this. Not a problem when lapping as much as grinding and then lapping.The crank is end play controlled from the front iron, so the crank is pushed to the rear as the stack gets shorter. Some folks would not take this into account and build an engine that had the front end of the rear main bearing riding up on the radius on the rear of the crank. I have had them remove the engine and then the flywheel at the track, in order to remove the rear stationary gear and scrape the front end of the bearing
Then replace the rear stationary gear with a spacer made from cardboard from a Budweiser 12 pack.
Never a problem. I have also found this problem on new parts. So I scrape the rear main before assembly on every engine build.
I used double lip seals in the rear main. One lip facing forward to keep oil in the engine and one facing the rear to keep dirt out of the bearing. You can also buy half width seals and put in two seals. If you use two or a double, put some grease between the seal lips so they cannot run dry. This is a must when using a dry sump pump as the engine may well be running internal pressures below ambient, (local air pressure) and trying to pull in dirt past the seal.
For normal sump engines I remove the spring from a new seal and shorten the spring about 3/8" and reinstall it. This also helps keep oil in the engine during a side seal, and or, "O" ring failure. Oil staying in the engine is good yes? Some assembly may be required.
LEH
In a message dated 6/14/2020 2:43:17 AM Eastern Standard Time, flyrotary@lancaironline.net writes: