sparky77

iTrader: (1)

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

fccs

iTrader: (26)

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!

sparky77

iTrader: (1)

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

fccs

iTrader: (26)

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.

Super Speed

iTrader: (8)

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!

SOMbitch

iTrader: (8)

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.

fccs

iTrader: (26)

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

teke184

iTrader: (5)

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