4-Cylinder Rear Main Seal Conversion Kit

Like many British cars, both the four and six cylinder Big Healey use an "Archimedes screw" or "oil control screw" cut into the rear of the crankshaft. The "threads" are designed to work with a surrounding housing which comes very close to the surface of the crankshaft. As the crank rotates, the "threads" draw the oil back into the block. When everything is brand new, this actually works surprisingly well. However, with time, leaks can develop, which can be downright aggravating. If you have the engine out, think about installing a rear main seal conversation. The basic idea is the same for both kits - an aluminum housing positions a modern lip-type seal around the crankshaft. Done properly, the seal works very well. It makes sense to include one as part of any major overhaul. In addition to the machine work, there are some items that you will need that are not in either kit. The most important are a drill and 4.2 mm drill bit, and a tap handle and 5 MM x 0.8 mm pitch tap.