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Stud Girdles
Pontiac V8 Stud Girdles
Tie the Studs Together — Stud Girdles for Pontiac V8s
A stud girdle ties all eight rocker studs on a Pontiac cylinder head together with one solid bar. Under high lift and heavy spring pressure a lone 7/16" stud flexes and the rocker geometry moves with it. Tying the studs together stops that deflection and properly locates them, which keeps valve lift where the cam ground it.
Butler stocks stud girdles from Butler, Comp Cams, Jomar and PRW, cut for factory cast iron heads and for Edelbrock and Speedmaster heads, most with 7/16" Polylocks included, plus replacement Polylocks for the PRW kits.
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More About Stud Girdles
1. What a Stud Girdle Actually Does
It is a stiffness part, not a power part, and it earns its place on a specific kind of engine.
| One-piece solid bar | the Comp girdle is a solid bar, one-piece design that ties the studs together as well as properly locating them. It is made of 6061-T6 aluminum for light weight and anodized for durability. |
| Complete kits | the Comp kit comes complete with hex head adjusting nuts, interlocking set screws and all hardware, so the adjustment method changes along with the girdle. |
| When you need one | high lift cams and high open spring pressures are what bend studs. If the engine is a mild street build on stock pressures, a girdle is not doing much for you. |
2. Cast Iron or Edelbrock: They Are Not the Same Part
The girdle has to match the stud spacing of the head, and Pontiac has two families here.
| Factory cast iron heads | the Comp girdle fits Pontiac V8 cast iron heads with 7/16" studs, and the PRW cast iron girdle fits factory Pontiac heads with Polylocks for 7/16" studs. PRW notes that girdle also fits Kauffman D-port heads. |
| The 389-421 and Ram Air V exception | both the Comp and the PRW cast iron girdles specifically exclude 389, 421 and Ram Air V heads. Those castings do not take these parts. |
| Edelbrock and Speedmaster | Butler's own girdle kit is cut for Edelbrock heads and includes 7/16" Polylocks. Jomar offers the Edelbrock girdle with and without Polylocks, and PRW offers an Edelbrock and Speedmaster version with Polylocks for 7/16" studs. |
3. Polylocks and Adjustment
A girdle changes how you set lash or preload, so read what is in the box.
| With or without | the Butler and PRW kits and the Jomar kit include Polylocks. The plain Jomar girdle does not. If you already have good Polylocks, buying the bare girdle makes sense. |
| Replacements | Butler stocks PRW replacement Polylocks sized for the PRW girdle kits, so a damaged lock does not mean a whole new girdle. |
| Everything is 7/16" | every girdle in this category is built around 7/16" rocker studs. If the heads still have 3/8" studs, that conversion has to happen first. |
Tell us which head castings you are running and whether you already have Polylocks, and we will get you the right girdle the first time.
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.