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Rocker Accessories- Polylocks, Lock Nuts, and Rocker Balls
Pontiac V8 Rocker Accessories- Polylocks, Lock Nuts, and Rocker Balls
Hold Your Lash — Rocker Accessories- Polylocks, Lock Nuts, and Rocker Balls for Pontiac V8s
Rocker accessories are the small parts that hold your valvetrain adjustment where you set it. On a stud-mounted Pontiac V8 the lock nut or poly lock is what keeps the rocker from backing off under spring load, and the rocker ball is the pivot a stamped or roller-tip arm rides on. Get the thread or the stack height wrong and you will chase lash forever.
Butler stocks 3/8 poly locks from Comp Cams and PRW, 7/16 poly locks from PRW sized for roller rockers, 3/8 and 7/16 lock nuts from PEP, grooved rocker arm pivot balls from Melling for 7/16 studs, and Pioneer 7/16 stud adjustment washers sold each or in sets of sixteen.
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More About Rocker Accessories- Polylocks, Lock Nuts, and Rocker Balls
1. What Each Piece Actually Does
Four different parts get lumped together under rocker accessories, and they do four different jobs on the stud.
| Lock nuts | the original stud-mount adjuster. PEP offers them in 3/8 for studs with a 3/8-24 thread and 7/16 for studs with a 7/16-20 thread. On a stock or stock-replacement rocker, a lock nut is all the factory ever used to set and hold lash. |
| Poly locks | a two-piece adjuster with an internal set screw that jams down on the stud so the outer nut cannot walk under spring load. Butler carries 3/8 poly locks from Comp Cams and PRW, and PRW 7/16 poly locks sized .550" OD by 1.150" for roller rocker arms. |
| Rocker balls | the pivot a stamped or roller-tip rocker rides on. The Melling grooved rocker arm pivot balls are for 7/16 studs, and the groove carries oil across the loaded face instead of letting it run dry. |
| Adjustment washers | Pioneer 7/16 rocker arm ball and stud adjustment washers, .110" to .115" thick, sold individually or as a set of sixteen for shimming the stack up off the boss. |
2. Thread Size Decides What Fits
Nothing here is chosen by displacement. It is chosen by the stud that is already in the head, so measure before you order.
| Match the nut to the stud | PEP 3/8 lock nuts are for a 3/8-24 threaded stud and PEP 7/16 lock nuts are for a 7/16-20 threaded stud. A rocker that takes a 7/16 ball still needs a nut that matches the thread on top of the stud, and those are not always the same number. |
| Upgraded studs | Butler's 7/16 rocker arm stud upgrade and conversion kits use 7/16 lock nuts and work with existing 7/16 rocker balls, which is the usual reason a Pontiac ends up with 7/16 hardware on a head that left the factory with something smaller. |
| Roller rocker sets that already include locks | the Butler Exclusive Tru-Ratio Endurance Series sets include poly locks, Crower Enduro sets include sure-locks, and Butler Stainless Pro Series sets include RockerLocs. Buy loose poly locks to replace a damaged one or to finish a set that arrived bare, not because you assume none are in the box. |
3. The Poly Lock That Bottoms Out
This is the failure that sends people back to the counter, and it is not a defective part.
| What happens | the poly lock body runs out of stud before the internal set screw has anything left to jam against, so the adjustment will not hold no matter how hard you tighten it. Butler's own 7/16 rocker stud upgrade kits ship with machined washers for exactly this reason, so the poly lock does not bottom out and still has room to lock. |
| The fix | a 7/16 adjustment washer under the ball or the lock raises the whole stack and puts the adjuster back in the middle of its range. That is what the .110" to .115" Pioneer washers are for. |
| Check it on the bench | stack a rocker, ball and lock on a spare stud before the engine goes together. You want threads showing above and below the adjuster at your final lash setting, not a nut hanging off the last thread. |
4. Stock Rebuild Or Roller Valvetrain
Both paths land on this page, and they buy different things.
| Putting a Pontiac V8 back together stock | factory-style stamped rockers on the original studs need pivot balls and lock nuts. Replace the balls if the old ones are grooved, galled or blued, because a worn ball wipes out a new rocker in short order. |
| Building for lift and spring pressure | poly locks are the right answer once you are into a performance cam and heavier springs. The set screw is what keeps lash from walking as loads climb. |
| Order in sixteens | these are per-valve parts. Sets of sixteen cover the engine; singles are for replacing the one you lost on the shop floor. |
If you are not sure what thread is in your heads, pull one rocker, bring the stud size and the rocker style to the counter, and we will match the nuts, balls and washers to the parts you already have rather than guessing from the year on the title.
Not sure what your Pontiac needs?
Email our tech team at tech@butlerperformance.com. Tell us your engine, heads, car, and power goal, and we will put the parts together as one combination that works.