I know this isn't for an f-body but if anyone could help me out I'd really appreciate it.

I'm rebuilding a 350 for my 1990 Suburban and was thinking of putting a low-duration cam in there while I have it apart. So I was wondering if anyone knows how much valve lift those stock springs will hold. Thanks in advance

 

I think you will find that the stock springs will support no more than about 0.470" of lift. Any more than that and you'll be in danger of either valve coil bind or bashing the retainer into the valve stem seal. You can maybe go to half an inch of lift, but you'll need to carefully measure the valve installed height retainer to valve stem clearance, and spring coil bind height.

Besides, if I were you and I was changing a cam, I'd simply pay the extra sixty bucks and put in a new set of springs that are optimized for the cam. Then you'll only have to worry about installed height and retainer/seal clearance.

 

Up to .470 eh? The one I'm looking at is .440/.454 with 210/216 @ .050

If I do decide to put this cam in it, would I be ok? If not, could you point me to some springs that would not require machining to the head?

 

That cam should be fine. I'd sugget new springs anyway. Comp Cams #981-16's are plenty good for your application. That'll be a good cam with just a hint of chuff at idle.

Put in some new valve stem seals while you are at it! The black nitrile rubber boots seem to be the best ones for both intake and exhaust. The plastic cups crack and eventually fall off.