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Rocker Arm Studs
Pontiac V8 Rocker Arm Studs
Screw-In or Nothing — Rocker Arm Studs for Pontiac V8s
Rocker arm studs carry every bit of valve spring load on a Pontiac V8, and the factory press-in stud is the weak point as soon as spring pressure goes up. Screw-in studs, and the machine work that goes with converting to them, are one of the first things a hydraulic roller or solid cam build needs.
Butler carries 7/16 rocker arm studs from ARP, Comp Cams and PEP in several installed heights, Butler upgrade and polylock conversion kits split between 1961-66 389-421 heads and 1967-and-later heads, and a press-in replacement stud with a 1/2" base for 389 and 421 castings.
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More About Rocker Arm Studs
1. Installed Height Is the Number That Matters
Studs are not interchangeable by thread size alone. The installed height sets where the adjuster nut sits, which sets rocker geometry and whether the valve cover goes back on.
| 1.750" installed height | ARP-135-7101 is a 7/16-14 x 7/16-20 stud at 180,000 psi with a .800" screw-in depth. Butler recommends it when converting from press-in studs because of its reduced hex thickness. PEP-PRK382B-16 is also a 1.750" black oxide Grade 8 stud with the hex on the shank. |
| 1.900" installed height | ARP-100-7101 (180,000 psi) and ARP-200-7201 (200,000 psi) share a 7/16-14 base with .750" screw-in depth and a 7/16-20 adjuster. The Comp CCA-4512-16 set is a 1.900" stud with a guideplate locator shank. |
| 1.935" | BPI-1022-EDL-16 is the direct replacement rocker stud for Edelbrock Pontiac aluminum heads. |
| 2.000" and 2.100" | ARP-290-7201 is a 2.000" stud with a 1/2-13 base and 1.025" screw-in depth — note that you may have to cut the bottom of the studs to get correct length. ARP-334-7203 is a 2.100" stud on a 7/16-14 base. |
2. Converting Press-In Heads to Screw-In
Factory Pontiac heads came with pressed-in studs. Going to screw-in is machine shop work, not a bolt-on.
| The standard route | the stud holes get drilled and heli-coiled for 7/16 threaded studs. Butler recommends heli-coil plus ARP-135-7101 studs for that conversion. |
| Early 389-421 heads need more | on 1961-1966 389-421 castings the stud bosses also have to be milled, and that should be done by a qualified machine shop. Butler's 1961-1966 upgrade kits ship with the thinner-hex ARP-135-7101 stud for exactly that reason. |
| The shortcut kit | SPE-RAS3-STUDS replaces press-in studs on 389 and 421 heads with a stud that is 1/2" coarse thread at the base and 7/16 at the top, .75" coarse thread length, 1.00" fine thread depth, 2.25" overall, set of 16. The heads still have to be tapped to 1/2" by a shop — hand tapping is not recommended — but it skips the heli-coil, boss machining and base-cutting routine and still lets factory valve covers fit. |
| Pre-1964 oiling | some early heads oiled the rockers through the stud. Those studs have no oil-through hole, so run rocker arms and pushrods with the oil hole for stud-oiled applications. Those heads also have less material left around the stud and can crack. |
3. Upgrade Kits by Head Year
Butler packages the studs with the nuts and washers so the conversion arrives as one box, split by which heads you have.
| 1961-1966 389-421 heads | the 7/16 stud and lock nut upgrade kit, or the polylock version, both in sets of 16. Grade 8 studs with a hex on the shank, 7/16 lock nuts, and you can reuse existing 7/16 rocker balls. |
| 1967 and later heads | the same two choices in the later-head fitment, stud-and-lock-nut or stud-and-polylock. |
| Why the polylock kits include washers | the machined washers in those kits keep the polylock from bottoming out and leave room for the lock screw to actually lock. |
4. Torque and Setup
Two numbers do most of the work here, and one caution.
| Screw-in studs | Butler's Pontiac chart lists screw-in rocker studs at 55 ft-lbs with engine oil. |
| Non-adjustable rocker nuts | 20 ft-lbs with assembly lube. |
| Converted heads are the exception | on press-in-to-screw-in conversions there is no generic torque figure, because every head has a different amount of material left in the boss. Early heads in particular are easy to crack. |
| Check the whole stack | stud height, pushrod length and rocker geometry move together. Set installed height first, then measure for pushrods. |
If the heads are going out for spring work, have the stud conversion done in the same visit. Pulling heads twice to fix stud height is the most avoidable job on a Pontiac valvetrain.
Not sure what your Pontiac needs?
Call our tech team at 866-762-7527. Tell us your engine, heads, car, and power goal, and we will put the parts together as one combination that works.