OK, the oil gurus have spoken, and I agree. I've used 15W40 diesel-rated oil in everything I run, including the lawn mower, for several years. No problems yet!
Now, for the "why" of breaking in a cam above idle speed. Virtually everything inside the engine except the cam runs with at least some clearance between the parts. The cam/lifter relationship is a scuffing motion that requires a high film strength oil, and lots of it, especially during the critical break-in period when the cam lobes and lifters are establishing a running fit. The idea behind breaking in at high speed is so the oil slinging off the connecting rods and crankshaft will keep the cam flooded with lots of oil. As soon as you see the oil pressure come up, pick up the speed and hold it, no idling at all if possible. Run the engine at a constant speed of 2,000 RPM for 20 minutes or so, and don't worry about blipping the throttle. Make sure the cooling system is FULL, no trapped air. I've had a couple of cooling system gushers during a break-in run due to not gertting the cooling system full enough before startup. Once the wear pattern is established, idling won't damage the cam lobes.
I like to static time the engine by bringing the timing marks into alignment with the distributor rotor pointed toward the #1 plug tower, then turning the distributor housing in the direction of distributor rotation until the points close, then turning the housing opposite rotation until the points just break. That will get the ignition timing set within a couple of degrees of the correct setting. If you have a 12 volt test light, connect the light from the distributor side of the coil to ground. With the ignition switch turned on, the light will go out as the points close, and light up as soon as you turn the distributor far enough in the advance direction to open the points. That's a litle more accurate than just eyeballing the point opening.
Jerry
