Reply to "oil restrictor kit"

The cam bearing oil passage restrictions only help a little. Installation of tappet bore bushings with 0.060" orifices remedies 90% of the lubrication system's problems. Now the tappet bore bushings are the items that could possibly interfere with the operation of the tappets. But not to worry, based on personal experience and the experience of many others the bushings are perfectly safe for use with hydraulic tappets ... so long as the bushings are installed in all 16 tappet bores and the big restrictor is not used. Thus modified the performance of the lubrication system improves tremendously regardless of which type of valve train is chosen. A comment I hear repeatedly after someone installs the bushings is they'll never build another 351C without them.

Back in the late 1970s I decided I needed more horsepower, so I installed a solid tappet camshaft in my daily driver (1971 Mach 1 Mustang, 351C 4V, 4 speed top-loader, 3.91:1 gears). Installation of tappet bore bushings went hand in hand with installation of the solid tappet cam. My methodology deviated from the norm back then in that I installed bushings in all 16 tappet bores. After a few months I realized I had made a bad choice. I didn't like driving the car daily with that rough idling cam in it, so I reinstalled the hydraulic cam .... and a set of new Johnson HT900 hydraulic tappets went back into the tappet bores which had been modified with bushings. Nobody I knew had ever done this, so I had no idea if it would work or not. I had a spare engine standing by if it didn't. But as it turned out, the hydraulic tappets worked just fine with the bushings in place. All the way to 7000 rpm, which that engine could pull even with hydraulic tappets. No ill effects. The engine had over 200,000 miles on it in the early 1990s when one of my son's took the car for a joy ride that ended in disaster.

cheers Mike