Your 421 Pontiac Superduty is being built for performance. Your new camshaft has higher lift and spring pressures. You have assembled the motor as per spec.Now at the light you stomp on the gas pedal and your press in studs lift out of the head and your motor is a boat anchor. Well, we have solved that problem. Now that the desire to build Higher Performance Pontiac 326, 350, 389, 400, and 421 engines is there, you will need to have this item. These will replace your Press In Studs. No longer will you have to wonder when they will press out. These are the correct thread, height and hardness. Made out of superior steel and without the custom oiling hole that is usually not needed anyway. If you have a real early 59 or so motor that oils thru the rocker arm studs you can still utilize these. Just install the correct hydraulic lifters and pushrods. Fact is that those oil galleries were problematic anyway. These have been designed to fit under your early valve covers and not dent them. They will accept "Locknut" style or "Self Locking nuts" and not hit the valve covers.
These are 7/16ths in diameter, not the 3/8ths bottleneck diameter. You will also receive our Custom Lock Nut set.This kit will Reengineer one set of Press in Stud "Boat Anchor" Heads into High Performance Heads. Best thing is that you do not have to face the stud boss. Nice to have the correct Rocker Arm Stud in the first place. 100's of engines have our studs in them.
They seem to hold up even to High Spring pressures associated with Roller Camshafts. Please remember these are best installed by a competent machinist. The item "Pontiac GTO Screw in Rocker Arm Stud Kit" is in sale since Saturday, January 22, 2011.
This item is in the category "eBay Motors\Parts & Accessories\Car & Truck Parts\Engines & Components\Rocker Arms & Parts". The seller is "wsuperdutyfirebirds" and is located in Auburn, Washington. This item can be shipped worldwide.