We offer 170,000 psi hold down bolts or hold down stud kits (preferred) to positively secure the rocker shaft to the cylinder heads. Stud kits include: studs, washers and nuts. Also available - rocker shaft hold down clamps. These clamps are used on our roller rockers and are a popular upgrade for stock shafts or our Heavy Duty shafts with stock rockers. These heavy steel clamps are placed over the shaft at the bolt location and distribute the clamping force over a greater area were it is needed most. Use TA 1323A Rocker Shaft Stud Kit with the hold down clamp kit.