I was just reading this link http://www.ls2.com/forums/showthread...646#post327646
(needs to be a permanent sticky very good info)

and I found the difference between my lift at .006 and .050 is 53 a number which seems to be right in the middle, denoting not an aggressive lift cam (xer grind) nor a mild lift cam (xe grind). This is a lingenfelter gt2-5 cam.
The heads have a larger 2.00 intake valve and .050 milled-going in 5.3

My question for all you guru's is with this setup can I run higher ratio rockers like 1.8 or 1.85? I know the xer grinds you arent supposed to but this cam is right in the middle with the higher ratio and higher lift would I run into clearance problems?

 

nobody has any input?

 

What are you after? What are your goals?

 

better rockers since Ive heard the stock ones tend to drop bearings. With a larger ratio I get more lift and duration.
Im thinking ahead if Im not happy with heads and cam gains.

 

Reason I ask is because I've heard the same thing about the stock rockers, but I've also heard that percentage-wise, the issue is pretty damn infrequent. I've done a fair bit of reading on the topic and the common wisdom seemed to say that if you want more duration and lift, to get a cam with more duration and lift, don't mess with rockers. I've heard of a fair number of issues with aftermarket rockers, too - they're not immune.

Good luck with your decision.

 

I guess Ive got some reading to do thanks for the input Naked

 

Yeah, check out the Engine Internals section, great place to do some searches.

 

One thing about the stock rockers, is that even though they're rated at 1.7's... they actually start lifting the valve at 1.54 ratio. They reach 1.7:1 later in the lift cycle. They seem to give up a lot of lift/duration there.

I'm not sure if clearance problems would be the issue... or if it would be more like "overstressing" the lifters on an agressive ramp, trying to push the valve at a higher ratio... I wish I could give an answer on that, but I just don't know the dynamics of it all.

There is some good info on rockers in the first few paragraphs here. You may be able to achieve what you're look for through either of those products.

I know there are some out there running the 1.79's on higher lift cams in the .560 to the .580 range.

 

Been reading but the question still remains is anyone using a moderate-aggressive lift cam with aftermarket rockers 1.7 or higher. From what I gathered on the above article and marc_w is relating is that even if we replace the stock rockers with aftermarket ones of the same ratio, that increases the valve events and gains are to be had. I guess 1.7 to GM and 1.7 in the aftermarket community are two different things.

The only reason Iv even considering this is my heads havent been ported and I think alot of guys (like me) could gain from cam and rockers, plus it means you dont have to put down 1500 for just heads.

someone correct me if Im wrong

 

Valve events do not change with rocker ratio changes. Meaning there is no change in duration.

Valve events = duration vs. lobe distance vs lobe centerlines

Picture a valve riding on a lobe. Increase the valves length. As it's riding around the lobe, the valve is now opened further. Not for longer amounts of time (duration)

That's an easier example then picturing an entire valvetrain. Simplified definetly.