I finally got my Vortecs so I can start mockin em up. Well, I pulled out the springs since Im replacin em with the one from the cam kit. Well, the cam I got is pushin .490 lift. Ive heard so many variations on the safe amount of lift you can have on the L31s. Well, to my suprise, I installed 1 ex and 1 In valve and measured the total clearence between the retainer and the valve steem seal. I measured about .510!! Most places Ive looked up Vortec info on said that you can only get a total of .470 and thats with no clearence. Most places dont recommend goin over .420 or .450. Did I get lucky, or can I really get .490 lift out of these vortecs with no machining, and still have appx. .020 clearence from retainer to seal?

 

The unconfirmed answer is NO. You're going to bind the springs, or hit the spring boss.

But I don't know if anybody has actually done this... so it could be fine. Watch out for those push-in studs though, they have a tendency to tear out.

 

Thats unusual. The one set of factory assembled vortecs I checked were right at .450" from retainer to seal.
All the other sets I set up we machined the guides and springs seats for aftermarket stuff.

Anyways a .510" clearance is really not enough for a .490" lift valvetrain. You would want a minimum of .060" additional clearance at full valve lift, or in your case .570".

 

Where did your heads come from? The ~.450 number is for the stock heads with the stock seals that were used in production. Could be you've got some different seals.

 

They're just regular GMPP Vortecs. The guy that originally bough them said he didnt do anything to them, just bolted em on. He said he was pushin .485 lift! Im gonna look into more detail on this when I get to work, something just seems fishy