I am installing vortec heads on a 383 with a comp cams xe268 cam with .480 lift. I was told that I may have to get the valve guides cut down to use this cam does anyone know if I need to do this or not? Also I was wondering how many times ARP main bolts can be torqued? If I'm just checking clearances.

[This message has been edited by nelliesIroc (edited June 19, 2001).]

 

I can't help with the valve guide boss, but generally if you're using new main bolts/studs, you should be able to torque and retorque as many times as needed as long as they've never been heat cycled...I don't think the torque on most street motors are torque-to-yeild, so I wouldn't worry about it, least I never have.

 

i don't know the exact number but i believe .480 will give you clearance problems, if it doesn't you'll be real close to it. dummy up one head and a pair of valves and check the clearance. you could have .100 milled off to be safe too, the cost shouldn't be much.

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Since Vortec heads are replacement truck heads, not performance heads regardless of their flow, as they come from GM they are not set up for any kind of performance use. It simply didn't enter into the picture when they were designed. So, to use them for anything more than the most basic performance-oriented application, you have to modify them.

Their first limit is the valve guide height. like ede said, .480" is about all there is as they come out of the box, and some people have had trouble with even that little lift. If you plan on using a cam with anywhere near that lift, it would be extremely wise to check that clearance. Checking, and fixing the problem if necessary, is a whole lot less trouble and expense than cleaning up the mess that will be created by the retainers hitting the valve guides at 5 or 6000 RPM.

Once you start spending money to turn those heads into true performance parts, the "economy" starts to go away in a hurry. If you install better valves, screw-in studs and guide plates, machine the spring pockets for real valve springs, etc., you'll have as much money in them as you would if you had just gone out and bought the right thing in the first place.

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