Hello all - So my question is about oiling/lubrication of the rocker arms on an older model Vanguard V-Twin engine. Specifics are an early 1990s 16 HP horizontal shaft 303447-0326-01. This has the older style rocker arms where both arms on the head mount to a single shaft. The push rods (one steel for intake and one aluminum for exhaust) are solid, not hollow. Now, after some repair work on the top end, (rocker arms and push rods), I have it back together. When I spin the engine with the electric starter motor, with no spark plugs, I get good RPM, the valve train seems to be working correctly and I have 40 PSI oil pressure indicated on the oil pressure gage I added. Oil is getting through the system up to the cam shaft however, I don't see any oil making it to the top end of the head to the rocker arms. How are the rockers SUPPOSED to get oiled? Looking down into the head along the pushrods, I can see the cam shaft through a small access port. Does the top end get oiled via the "sling" effect of oil coming off of the spinning cam shaft? I guess with the higher RPM of the engine running vs just spinning with the starter, and warmer oil with the engine running enough oil would sling up to the valve cover? Can anyone confirm this is the true/proper oiling method for the rockers? It just doesn't seem like there'd be enough oil getting up there. There are a couple videos related to oiling/lubrication on the Briggs & Stratton web site, and while they are fair, they don't show lubrication of the rockers. I don't want to actually start and run this engine without being confident the top end will get adequately oiled. Thanks for any comments!
#2
Hammermechanicman
Briggs engines with solid lifters oil the valvetrain by mist oiling. The oil in the crankcase is whipped onto a mist, not vapor, by the crankshaft that lubricates the valvetrain. Engines with oil pumps push oil to the crank for the con rod and upper bearing but not the valvetrain. So engines with an oil pump are a combination of pressure and splash lubrication
Thanks for the explanation. Seems like there should be a little more active oiling, particularly on a horizontal shaft engine with the rockers on top of the heads so far away form the oil sump. But OK!! Thanks again.
#4
Hammermechanicman
If you look at a briggs flathead engine the mist must travel through a hole about 3/8"" to get into the valve spring chamber to lube the valve guides.
