Description of Small Block Chevy Stage 8 (8911B) 1-1/4" Header Bolt Kit
Grade 8 bolts will not stretch when hot. Duplex nickel finish for a superior look and corrosion resistance. Double Hex Head includes 3/16 inch recessed Allen Head for easy installation. Removable and reusable. Can visually inspect - no need to put a wrench on to check tightness.
As an automotive enthusiast, I was excited to test out these headers, but they did not perform as expected. As a result of my tests, I determined that these headers did not improve the exhaust flow or horsepower of my vehicle. The installation process was also challenging and time-consuming.
When using non-original manifolds, the screws must be 1 1/4 be to fit properly. With the Stage 8 header mounting bolts, you don't have to worry about them being reversed. Run the engine for 15 minutes, then retighten and secure the bolts.
Pros
The double hex head includes a countersunk 3/16" hex head for easy installation
Prompt delivery, packaging on time. Great product, works well to not unlock when hot or cold. The only problem they have is a hex head with a hex wrench hole in the middle of the bolt because you can't tighten the bolt! ! !