SPAL v3 fan controller w/Intrepid dual fan setup Vortec 062 heads w/screw in studs 1.5 rockers Great low end torque and pulls all the way to 5k. In my setup it seems to like the 1.5 rockers and 670 carb for street use. I don't know if Paul minds, but nastyz28 has a definitive guide on Vortec heads here I used a 1/2' drill bit and drilled mine out. You'll also need to drill out the pushrod holes because they'll rub. You'll need to change the keepers or change the springs (which is what I did). 525 with a 1.6 rocker, which will bind a stock vortec spring. If you go to the 1.6 rockers you will want to do a couple of things, both of which have to do with binding / rubbing. That sets you up for 1.6 rockers down the road. You'd be better off swapping in some springs and having the heads machined to take. Some can take the lift of the HOT cam, some can't. Seat pressure on stock springs is fine with the 1.5 ratio (stock) rocker arms but lift is the problem.
