I'm building a 302 for my truck and I bought some roller rockers for it, but there 3/8 stud mount rockers and my factory heads I'm using have the 5/16 bolt on style. So they won't work unless I machine bigger holes for them to put studs in, whichwas what I was planning on doing, but does anybody know how to go about doing so? Meaning is there a special angle to drill the holes, any milling that needs to be done and so on. If anybody has done this and knows what kind of specs I should tell the machine shop that would be great.

 

You should let a machine shop do this. There is a tool to let you do it but I've heard it's very hard to get them all straight. Besides, you need to have the heads machined to accept the guide plate you will need to run plus use hardened pushrods
Clint

 

I hear the Pedestal mounted roller rockers are more stable than the Chevy style studs. 3/8 isn't much stronger then 5/16 and the pedestals only hold everything down and don't wobble like a Chevy train. I spent a lot of money making my Chevy turn 7K. BTW I am planning to use them myself and they are made by Scorpion for your 302 as well... They cost about the same price you will pay a machine shop to convert your heads to studs. The Scorpions are rated to 700 or 800# and come with the pedestals. Now you can also help me as I have bare castings. Do the pedestals mounted rockers use anything to stablize the push rods like a guide plate? With them not wobbling like a stud I can imagine they may not use anything more than the pedestals, rockers and push rods. If so I can't find a part listing for them... Hope we can help each other... Looks like your ratio choice is 1.6 and 1.72 so you would not need as much cam lift if you have not aleady bought one. : ) If you figure out stock ratio and what cam you want to use I will be glad to help you with the cam selection using a larger ratio arm.

1.72 ratio: http://fastengineparts.com/products_view.php?id=580

1.6 Ratio: http://fastengineparts.com/products_view.php?id=578