Posted by Jack Smith on July 16, 1999 at 15:09:28:
In Reply to: Tips on reinstalling engine? posted by Dave Horvath on July 15, 1999 at 10:12:59:
Guys,
We have a lot of V-8 guys in here, from the sound of things. A few thoughts as I read these notes:
DON'T run a newly assembled flathead at anything near 2000 rpm. It'll shorten the engine's life quite a bit, if it doesn't break something right off.
It's not necessary during pre-lube to build oil pressure. Just be sure that oil flows through all the galleries and bearings. I do this with a gizmo I made. I use a clean 30 pound freon tank into which I pour the correct amount of oil for the new engine. Stick a hose barb fitting in the oil pressure sending unit hole, and run it to the tank. (use any kind of tank that will tolerate a bit of pressure. Clamp the hose. Apply air pressure to the tank, forcing the oil into the engine. It'll flood the bearings and rotating parts, and leak down to the pan. Check your level and start her up. Don't overdo the air pressure or your seals will leak. A couple pounds is plenty.
The oil pump/drill trick works poorly on the flathead, for several reasons. The pump is such a pain to retime once you disengage it from the cam gear, and the gasket and/or rubber bushings, depending in which setup your engine has, should be installed new, tightened, and then left alone, or a leak will result. A suction leak at the pump base can destroy an engine running at speed with very little warning.(always replace the safety wire on the pump bolts. If your bolts are not drilled, drill them and wire them.) After building somewhere on the order of three hundred-plus flatheads over my career, I must admit that I have never encountered the thick fiber gasket for pump priming. Judging from the length of the oil pump gear, this fiber thing would need to be about 3/4" thick. The bolts are too short, etc....how about someone sending me one of these fiber gaskets? I'd love to see one in person.
The idea in "breakin" is to vary engine speeds in order to let engine vacuum pull oil up onto the cylinder walls, to carry away dross as the walls wear in to the rings and vice versa. If this dross remains as the crosshatch wears, it'll glaze up like a loaded whetstone. I use a system I read about many years ago, in which you get out on the road, accelerate gently to 30 mph or so, then leaving it in high gear, allow it to slow back to a crawl. Without downshifting, lug it up carefully again to 30, etc. Do this several times, and that should be all the breakin the rings require. If bearing inserts don't seat in this time, they will not seat. As the rings gradually begin to conform more closely to the cylinder wall variations, you'll experience an increase in compression and engine power. This will probably top out long before 500 miles comes. Once this occurs, breakin has stopped and wearing the engine out has begun.
Change oil and filter as soon as possible after initial run-in. The idea is to discard the shavings and dross.
The difference between a new engine and a worn out one is a mere two ounces or so of metal, perhaps less. Any abuse early on in an engine's life will use up some of those precious bits, and bring you closer to worn out. An engine has only so many rpm's to give you in its life. Use them up fast, or use them more slowly...but you won't get significantly more no matter how you break it in. It's just a function of physics.
Hope this helps someone! Have fun!