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Ok if i have a set of stock cast iron 906 vortec heads and i want to get them ready for more lift to go with a XR276hr cam or the xr282hr cam, what all needs to be done? I am looking for details. Search has provided me with some genral direction. As in i know i need:
Screw in rocker studs instead of pressed in. Is this easy to do yourself or would you reccomend the machine shop do this?
Will need to upgrade springs to a set of comp (whatever they recommend for the cam) and i think to do so the valve guides need to be cut down? This is where i get a little confused. What is machined to accept better springs and why is it necessary?
Is there anything else i need to do?
Last edited by andrew91rs; 01-24-2008 at 02:44 PM.
Reason: forgot a word
If you have the guides prepped for positive-type stem seals, you'll cut the guide so that you can fit better springs, and will have more valve travel before the retainer hits the top of the guide.
If you're going to do screw-in studs, that's probably best left to a machine shop (although some have talked about shoulderless screw-in studs). If you're going to pin the press-in studs, you can probably do that yourself.
You can probably do all this yourself, but unless you're severely funds-limited, a machine shop is probably the way to go.
If Five7 is talking about the studs I think he is, those screw-in studs without the hex on them are just supposed to be repair only stuff. Like if a pressed in stud, for whatever reason, pulls out then you just tap the hole and thread it in. You can only thread it in finger tight (no way to get a wrench on them) and thread-lock them in. Did it once or twice at a shop I used to work at. Its fine for just replacing a pressed in stud in a stock motor, but they are not for a performance application, as they are noticeably thinner in the bare spot right in the middle, between the head-side threads and the rocker-side threads. If you do screw-in studs, have a machine shop do it properly and use parts designed for that kind of use, like good GM stuff or ARP stuff.
Time to bring this back to the top. I already got some screw-in studs, pulled the old studs and tapped the bosses. I completely spaced out and didn't have the bosses machined. I'm assuming they need to remove enough material to account for the hex on the studs and let the rocker sit at the correct height?
Yes, they need to be machined down for that exact reason.
I used those shoulderless ones, mrg-76 is the part number. Double nuts will tighten them down, then loctite red, or sealant in my case.
One loosened out on it's own once, and now it's loctited in.
Just do the screw in studs WITH GUIDEPLATES and use non self aligning rockers.
For LIFT, no machine work is needed. JUST buy Comp Cams 918 BEEHIVE springs and Retainers. The design of the retainer lets you get clearance up to about .550" lift. I am doing this now. springs $179 and retainers are about $60.
I am using the Titanium retainers....They are much more.
