I believe its .480 but with new locks and retainers that are +.50 you can use up to .530. But yes running that high would still be best to make room for more by pulling the heads. With doing so you you can pretty much run whatever. I know my cam is higher but i cant remember off the top of my head but I think its in my sig.

 

That is false
With the correct springs,retainers and locks you can run lift most would think is not possible on the vortec 350
I had a cam in my 97 L31 that had a 493/502 lift and the heads never even came off the block
It can be done with the right setup
The thing is most do not even think it is possible on stock heads
a buddy told me it can be done
He was right

 

Yup its .530 max with the correct setup supposedly. I ran my old cam that was around there before I had the heads worked.

 

While it is possible to obtain the necessary clearance to run more lift if you use Comp 915 Beehives or equivalent, that are designed for LS1's at an installed height of 1.800", instead of the factory SBC height of 1.750" you can obviously run more lift without the retainer hitting the valve guide or seal, but you will need a few parts to make it work.

To run LS1 style Beehives in a SBC designed with 11/32" valve stems, you will need to use a hybrid retainer. Comp makes such a retainer Part # 787-16. Also to get the installed height of 1.800" you will need a +0.50" steel lock/keeper and Crane makes just a jewel: Part # 99095-1, coded Yellow.

What ever you do though, don't attempt to install the +0.50" keepers on valve springs designed for a stock installed height of 1.750" or you will loose the required spring pressure. Also don't assume that because we were able to get that much clearance on Charlie's motor that you can too. In each case clearance will need to be verified.

Note: Comp's 915 & 918 springs will fit the spring pocket in a SBC without machining to the head and will also have the necessary clearance around the large valve guide that the Vortec head uses. For people who will get the idea to just use LS6 springs as a cost saving measure, while they will fit the spring pocket, they may not fit around the valve guide. The LS6 spring has a slightly smaller I.D. than the Comp's.

 

there he is

 

Also something to look at is the pressed in rocker studs, they can pull out when open spring psi gets near 300lbs.

 

dang good info on spring setup.....thanks!