390 rocker arm's
I am in the process of rebuilding a 390 I am asssuming the engine is a 67 or 68 It is out of a 67 ford ranchero It has adjustable rocker arms I have never seen an FE engine with them they have every appearance of being stock It is a 2 barrel carb equipped engine My question is what engine's or year's had these rocker arm's They have a lock nut and are adjusted with an allen wrench The engine definitly had hydraulic lifter's Any one know any history on these ????
High performance 390's in the mid-late 60's on Fairlanes, Torino's and Mustangs had adjustable rocker arms but to my knowledge they all had solid lifters and not hydraulic. I'm not sure what you have unless the rocker arms or lifters were changed at some point. I doubt it left the factory that way but anything's possible.
All FE engines originally equipt with a mechanical ("solid") lifter camshaft had adjustable rockers, as a means of setting the proper clearance ("lash") value. This also requires a pushrod of the ball & cup vs. ball & ball design as intended for the hydraulic camshafts with the nonadjustable rocker arms. Applications would include some early 352s, 352HP/PI, 390HP/PI, 406, 427, 428SCJ, not necessarily all, and some others, and some for some unknown reason, but never say never, as there always seams to be an exception.
Most of these consist of a ductile iron rocker arm casting; with a 7/16" x 20t interference thread, hollow stem, 7/16" hex wrench fitment, adjusting ball-stud; a single unit requiring no lock-nut, and cadmium plated to reduce galling. These were/are not good for to many adjustments before the interference thread value is lost, so Ford offered (now obsolete) these ball-studs as service replacements. Or, "back-in-the-old-days" one would hunt in the junk yard for an old "Y" block, which had a solid stem w/ screwdriver slot ball-stud w/ noninterference thread & a hex lock-nut which would retrofit (although heavier) into the FE rocker arm.
The units you describe (utilizing an Allen wrench fitment) would appear to be aftermarket replacements; which, at one time, where available from many vendors, but as of now, are obsolete (N.A.) from most if not all. Scott.
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