I just scored a nice set of vortec 906 heads. Yes these are the ones WITHOUT the hardened exahaust seat. Anyway what I need to do is prep these for larger springs. I have read in a few places that you can order specific cutters from both comp cams and crane to perform this. My question is this? Have any of you actually done this? If so was it hard? What part no.'s did you order? Im going to try this on my own no matter what. I plan to cut the guides down on a bridgeport mill and have seat cutters made if I have to. I will just use drill rod for a guide. This is a last resort though. Im hoping that you guys have done this and someone has my needed info. Let me know what your thinkin.

 

Actually those are the ones with hardened valve seats. After the early '70s all heads got hardened valve seats.

If you mean the ones with the heavy duty exhaust seats, yes those are the ones. The 062s are the ones that don't. But even so, there's no written law that says all 906 heads got the HD seats. Some did, some didn't. But the 062s never did.

Anyway, even if the heads you have do have the HD seats, it doesn't matter. They don't impeed flow as much as the rumor that was going around said they did. It was a rumor. Nothing more.

I know of another guy with the 906 heads on a 400 bored .030" running mid 11's in a 3,800 lb 2nd gen Camaro. So don't worry about it.

I can't help you with the spring cutter thing. I never really looked into it too much because I trust my machinist with $20 of my money (per head) more than I trust myself ruining $400-500 worth of cylinder heads. :shrug:

 

i'd pay a shop to do it, about 2 dollars a seat to open up. as much as i like doing this sort of thing myself i wouldn't use any of the DIY tools