What is the primary advantage of a fully adjustable valve train with a flat tappet hydraulic cam as opposed to a stock, non-adustable one?
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I did it! Not so much for the adjustability, as for the replacement of the stock 5/16" bolt that holds your rocker assembly together, with a 7/16" ARP Chrome-Moly STUD, AND a set of Roller Rockers, with Poly-Locks. And later if you wish to add a stud girdle,(not necessary unless for all-out racing), your all set up. Also when you take into account the thread root depth of the 5/16" bolt, the diameter is even smaller, and with the sharp thread root acting as a stress riser. I have wondered many times why we do not hear more stories of these smaller bolts breaking off, as they seem, in MY opinion, to be the bare minimum to get the job done. Especially with the heavy valves running at higher revs. Lastly, remember, a bolt depends on the threads to tighten up, where-as a STUD (almost)bottoms into the blind hole, tightening it up and locking it in place. On all my engines, ALL the fasteners are studs, not only for strength but also for RIGIDITY! Marlin.
[This message has been edited by MARLIN JACK (edited 11-02-2003).]
[This message has been edited by MARLIN JACK (edited 11-02-2003).]
[This message has been edited by MARLIN JACK (edited 11-02-2003).]
[This message has been edited by MARLIN JACK (edited 11-02-2003).]
Besides all that! Now I can call them "BOSS 351" Heads. Marlin.
On a street (that is, non-race) performance car, an adjustable valvetrainb allows you to run full roller rocker arms, which do not add significant power but do reduce the loaded oil temperature significantly, by reducing sliding friction in your engine. Additionally, it gives one a certain freedom to add any cam including a roller type, to adjust hydraulic lifter pre-loads (a little more revving before valve float) i fthats your cam choice, and to compensate for the position effects of multiple valve grinds over the years. Full roller rochers also seem to make valve jobs last longer and reduces wear on the valve guides. All this depends on an adjustable valvetrain. Some but not all these bennies can be had using a Crane adapter kit for the 351C that does not require machining the cylinder head rocker pedestals.