Re: 352-390 Oil passage blocked
The oiling system of the non-side oiler FE Ford engine needs some work before it will keep the engine alive at anything over 5500 RPM.
Oiling System Mods:
Drill out the hole where the oil pump mounts to the block to 5/8". Polish and blend it to the passage that goes to the filter adaptor.
Using a 1/2" drill bit 12" long, drill the main oil galley. You will have to go from each end. One thing you will notice is the fact that Ford intentionally put in a restriction in the back of the block just behind the cross drilled passages that feed the lifters. The FE block was designed in 1957 and was the first engine Ford used with hydraulic lifters. The engineers thought that they needed LOTS of oil pressure to the lifters so they put this restriction in to increase pressure. Since they never thought the engine was going to see anything over 4000 Rpm, they didn't worry about starving the bottom end. (We also completely blocked off all oil to the lifters.)
Next, use a 5/16 X 12" drill bit to drill out the passages between the upper part of the cam bearings and the main oil galley. They are 5/16 diameter from the main bearing to the lower part of the cam bearing, but the upper part is smaller. (Again, Fords effort to increase oil pressure to the lifters). Finally, at the cylinder heads, drill and install a plug where the oil feeds the rocker shaft. The plug should have a .060 hole drilled in it. You will be amazed how much oil still gets to the rockers.
This is what we had to do to keep bearings in our 352. We used to spin that engine 8600 on the starting line and shift it a 7500. Running under the old Super Stock rules, (1980's) The car ran 11.60's and 4070lbs using stock compression and the stock Auolite 4V carb.
These are pretty extensive mods requiring complete dis-assembly of the engine. A competient shop should be able to handle it. If you don't want to go that far on your oiling system, at least get rid of the restriction in the main oil galley. I know of guys who have had problems spinning bearings on the back cylinders. Removing that restriction cured the problem in every case.
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