That myth about tapping the main bearing cap assumes you're going to be replacing the front seal or the timing gears frequently. I see no point in doing it. The reason for doing things that way in the first place is a holdover from the 216 engine, when it might have been necessary to adjust the main bearing clearance with shims, and having the lower timing cover bolts accessible from the crankcase side made it simpler to remove the front main cap. Some designs of front motor mount made getting the bottom bolts out of the timing cover from the front very difficult. I've always been able to lower the crankshaft sufficiently to change a seal by simply loosening the other main caps. Since your engine is on a stand, it might be necessary to wrap a strap or an old fan belt around the crankshaft and lift it a little with an engine hoist.
Jerry
