This science is true with all engines that turn the cam clockwise when looking at it from the front. A groove on the backside is OK, but I prefer to groove the block and be done with it. Ideally you want a smooth solid front cam journal, and a full bearing without a groove. Adding 20/50, a HV pump and the stiffest spring you can find makes it worse. From 1977 to 1982, M-block (351M/400) engines were a mainstay of Ford light truck powerplants. If the cam journal has a groove that costs a lot in square inches of load area much like a groove on the cam side of the bearing. The front cam journal needs all the help it can get since it's at the end and not only does it have to contend with valve springs but it also gets loaded from the oil pump. Plus the oil you don't waste can end up at the lifters, rods, and mains where it needs to be. If you inject oil at the 4:00 position more off it goes under the cam where the actually matters. I wasn't going to replace the cam bearings as this engine only has 35,000 miles on it, plus they look good. THEN what's left makes it way to the load area where it can do some good. Looking down thru the main bearing saddles I can see 2 cam bearing oiling holes that are not compleatly open or not lined up 100 with the oiling holes. If you put it at the 8:00 oil hole location your pressurized oil will have to go up and over the cam journal (which is a wider clearance since the cam is pushed down) hemorrhaging oil the whole time. It seems these do as well on conventional as anything, but these days just about everything is a syn blend, even conventionals.The valve springs push the cam down towards the crank, so the load is at 6:00. Anything wrong with running Mobil1 HM oil in this old rig? I know the TBIs usually came with flat tappet lifters - is there another oil more suitable for that, or does it matter? I've owned several TBIs in the past but it's been years ago.
But, my go to right now would be 5w or 10w30 Mobil1 HM based on the coupons and rebates available for it right now. I would lean toward running QSHM or SuperTech HM in this beast.
So my question for any of you TBI owners out there is what oil to run? If there were no sales on full syn. Engine and trans was replaced at one point in its life, according to the PO, but of course no paperwork, so who knows. Lots of miles but this thing purrs like a kitten and shifts surprisingly smooth, completely free of rust. Money is tight for her, so we had to find a replacement vehicle on the cheap. These are stock type bearings, unsure ot mfg, but they look good, and in most cases I would leave them be. Thats about the only thing done correctly. A few weeks back the MIL got nailed by an uninsured driver. Got around to final washing the block today, and in blowing out oil galleries noticed that the cam bearings do at least seem to be installed correctly.
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