Oversize Engine Bolts

The Atkins Oversize Bolt Kit is designed to increase the structural integrity of the 13B engine under high horsepower applications.

The rear, center, and both rotor housings need to be drilled out with a 1/2" drill bit (not provided) to allow the oversize bolt to pass through. The front side housing needs to be drilled as well as to be tapped with the provided drill and tap.

At a bare minimum you will need a drill press to complete this task, the bolt holes in the front cast iron need to be straight and true, or the bolts will not thread when the engine is ready to be closed.

A tap drill and bottom tap are provided to re-tap the front side housing, remember to use sound practices when tapping any holes.

Five heat treated grade 10.9 bolts with a 12mm (M12x1.25mm) shank provide much more tensile strength and do not stretch like the stock tension bolts. Five tension bolt seals are also included to seal the bolts to the block.