Need torque spec for rocker arm nut

[kayden]

Me and a buddy took the rockers off my 1998 sierra with a 5.7 to check the push rods. I’ve looked for probably over an hour to find a torque spec and can’t find a definitive number. Hoping someone here can help me out.

 

[Schurkey]

The OEM nuts are self-locking. There is no "torque spec" for small-blocks and Mark IV big-blocks.

With the lifter for that rocker on the base-circle, tighten the nut just until there's NO up-and-down free-play in the pushrod. (Zero-lash) Then add "your choice" of lifter-plunger preload. Factory spec used to be one full turn. Most guys only go 1/2 turn. Some go less than that. Everyone has their own comfort zone for lifter preload.

Some aftermarket lifters have restricted travel, if this engine has restricted-travel lifters, "zero lash plus a RCH" is about all you'd need. But you probably don't have that kind of lifter on that engine.


There are about a dozen tried-and-true ways to adjust lifter preload on a typical SBC. Every way has it's followers who swear "their" way is best.

The absolute simplest, fastest, most fool-proof method is to loosen all the rocker nuts.
Tighten all rocker nuts only to the point where the pushrod has no up-and-down free-play. (Zero-lash)
Turn the crankshaft EXACTLY one turn.
SOME of the pushrods will now have freeplay. Tighten only the loose ones to zero-lash.
Tighten ALL the nuts "your choice" of preload. 1/2 turn is common.
Put the valve covers on. Have a beer.