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This is the 2nd of a series of “How to” articles. As promised the Mickey Mouse repairs More on crankcase and cylinder block seal. It is possible to stem the flow (of oil) in other ways. Always bearing in mind the differences in expansion of the two dissimilar metals. Both surfaces need to be flat and smooth, to enable some movement. The need to achieve same on the crankcase top deck can be done with a large file (very large) used as a draw file. The file for the job should be a 16 or 18 inch flat second cut, preferably 18 inch, with the last 2 or 3 inches wrapped with a cloth at both ends. Fix the bare crankcase to a bench vice or engine stand with the face up, lay the file at right angles to the crankshaft centre line and, with a light downward pressure, push and pull the file so as to cover the whole of the crankcase, including the starter motor section. Continue until the metal being removed feels like ball bearings under the file. Stop, clean the file with a wire brush and remove filings from the top deck . The use of clear kero will aid the operation, but too much will hinder it. After some minutes of activity, the two witness marks at each of the crankcase on the camshaft side should become highlighted, you will not need, nor should you, remove these witness marks completely, a reduction by half should be enough. This operation may take some time even if you spend 2-3 hours in toto it will no have cost you money. When you have achieved what you think is enough, wrap the file with emery paper of about 350 grt. Rub the crankcase top lightly in the same manner as draw filing. This should produce a smooth finish, you many need to move the emery paper 2 or 3 times per sheet to achieve a good result. Still using the file wrapped with emery paper smooth the bottom of the cylinder block in a similar action. Clean the cylinder block, oilways etc. using a good driveway oil dissolver. Hose clean etc. refit studs etc. then reassemble as follows. Cut the middle out of the standard cylinder block to crankcase gasket, this is because all the studs that hold the block to the crankcase are around the perimeter. Cut so that there is an equal amount of gasket either side of each fixing stud. Now, if you must use jointing compound, use only on the bottom side of the gasket, i.e. between the crankcase and the gasket leaving the top side or cylinder block face without jointing compound. Assemble the two and tighten the 8 nuts using a standard 5/16” BSW ring spanner. Tight but not too tight, remember with the rates of expansion one has to move on the other. Recommended jointing compound is “Loktite” Red. See I told you it is a Mickey Mouse Fix! JOHN BOWRING |