I feel compelled enough to be up at 4am to write this little piece. We are talking about one of the aspects of longevity. 1st. off doing what Walt did is fine with the stock pick-up tube diameter. But for the larger tube diameter there has to be something done to cut down the restriction caused by the washers. It makes no sense to put in a larger tube & then have washers that are a smaller diameter. We would be going from large to small to larger again. With some smaller washers you will have oil pressure but will have cut down on the amount of oil volume, by as much as 50%. Volume is as, if not more, important than pressure. Blueprinting an oil pump is enlarging the passage to the same diameter as the outer plug diameter & cleaning away all the casting "Flash". Smoothing all curves for a more gentle flow & checking gear to cover clearances. Another thing no one thinks about when raising oil pressure is the thin plate that makes up the cover. More pressure will easily distort this plate. We make a 3/16ths. steel ring to go around the outside diameter & held down with longer cover plate bolts. Loctited & wiretied. 5PSI oil pressure at a HOT IDLE is OK. As well as 25PSI while cruising & not putting the engine to too much abuse. As long as when you touch the go pedal pressure immediately rises. These things lived for 200K plus with an average of 35PSI. I know some that have lived to over 300K without a rebuild. The most common problem with low oil pressure when all the crank bearings are OK is more likely caused by cam bearings. Most have all the bearings installed & then pop in the cam & hope for the best. Very few ever check for clearance or, again, binding issues caused by cam bearings or cam bearing journal diameters. This is where you end up with insufficient oil pressure problems. The cam bearings get "Wiped" & the clearances become TOO much. Worst case the bearing or bearings will spin in the block. You need to install the rear bearing 1st. of course, but stop at the 2nd. from the back & install the cam & check for binding. You may be surprised at what you find. Do each bearing in turn ending at the front. We just spent over 4 hours doing just this to make sure there was no binding & sizing as nec. I say it all the time. When you think you have covered all the details go back I BET YOU MISSED SOME!!!!! What Walt has given is often overlooked advice. The only thing I can add is to make it easier, my opinion, is to cut a piece of thinwall pipe with the correct wall thickness to put in place of the washers. Easier to fit & size & the pick-up tube will keep it all in place. Just use Loctite as Walt mentioned & wire tie. We lost our last engine because of the bolts somehow coming loose. 50PSI is more pressure than any "Nail" needs even in "Racing" trim. What we have been blessed with is an extremely efficient oiling system. Oil goes to the cam & crank before going any place else. But, TOO much oil pressure is no good either as it will pass TOO fast & not have enough time to cool. One problem with higher oil pressures is at the heads. The drain back holes provided for at the pushrods are not large enough for oil drainback, especially when cold. The oil will actually fill the valve cover to the point of being sucked into the PCV system & you know what that causes. Billows of blue smoke that you will pull your hair out trying to find the cause. We are HP inefficient as it is, why would you want to lose more HP through parasitic HP loss with all that oil running down over the cam, good, & the crankshaft, bad, that's a HP loss. Everything comes with it's drawbacks. We don't have the pleasure of picking up some catalog & writing a check to make up for the mods we are looking to do to increase the HP. We need to think about the way we are going to make HP & the drawbacks associated with them. Every action has a reaction. Know what I mean??? As far as too much oil up top is an easy mod. Get a, about 1/4" set screw, drill a .030"-.060" hole in it. Thread the front rocker oiling hole in the head. This will restrict the amount of oil when cold & won't overburden the drainback. This has absolutely no effect on hot oil lubrication as the oil is thinner. Another problem is oil leakage at the rear of the head. How many times have you gone crazy trying to find an oil leak thinking it was the rear main or the filter adapter on the block when in fact it's oil weeping from the blocked hole from the rocker oiling hole that's not going anywhere's & just dead ends at the block. This is especially a problem with the composite head gaskets. Oil will weep it's way through the layers of gasket material. Easy fix. Take the same set screw & not drill a hole in it. Install the same way as mentioned. Now the oil can't go there. I don't know why the gaskets weep as there is really no oil pressure there, but it seems to happen mostly when O/P is increased. These set screws have no place to go. On the one end they can't go past the head bolts. On the other end they can't go past the rocker stand bolt. I do this on ALL, even stock, rebuilds. Eliminates an oil leakage comeback. We have gone as far as drilling 1/4" holes in the "Vee" of the heads to get oil to flow to the rear rather than down the pushrod holes. All to gain back some parasitic HP loss.
I need to stop now as it's getting nearer 6am & I need to take a shower to wake my dead ass up. Goodnight or Goodmorning depending on where you call home.
Tom T.
