What is the maximum lift that stock heads on a 99 LS1 can handle? I bought a comp cam xr275hr-12 and have it installed...but I'm nervous about the stock valve train. The lift is .566 intake and .568 exhaust...and 222 duration.
Can anyone help me out?

Thanks

 

Heads? lol alot more then that, a 5xx intake and exhaust lift is nothing. People are running cams with mid 6xx's like the ms4 and trex's on stock heads buddy!

 

Thanks, a buddy said they could only handle a .55 lift, which didn't sound right.

 

Yea if your buddy is saying that, then I wouldn't listen to him for anything about your car..lol. I have a 228r cam which is considered "SMALL" compared to other cams, and the lift is .588/.588 on it. I've seen people run huge cams or even custom ones with lifts up to like .635/.640 on stock heads fine. The big cams like trex,ms4,polluter, tsp giant, are all over .620's easy and people daily drive those cams with stock setups even.

 

x2 with that lift and duration you will be okay, now then, make sure you upgrade your springs, the stock springs are only good for the stock cam!

 

The heads are fine but the spings are not. You will experince valve float at upper rpm with those springs, PAC 1215's would be ideal for this use.

 

Yea the heads will be fine but make sure you change the springs def!

 

maybe your buddy was meaning the springs...stock springs are only rated to about .525" lift...and can barely handle THAT.