what rocker arms to run??????
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Teching In
Joined: Jan 2012
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From: Massachusettes
what rocker arms to run?????? I have a 416ci motor Turbo charged with trickflow heads and I'm running harland sharp rocker arms and my cam is 225/221-.621/.617-115 . I'm putting a new cam in which is 243/254-.638/.638-116 and pple are telling my rocker arms are no good and to usee my stock rockers', but others are saying stock rocker arms won't be good for a cam that big. I been looking everywhere for answers I just can't figure which rocker arms to run. Help please.
If TFS says roller tip then use rollers, they are better anyways. Everyone is on this stock rocker kick, I dunno why. There is power to be had from rollers and they keep the valve stem from deflecting as much.
I'd go with either Crane gold race rockers or Comp Cams 1500.
Valve float is caused by improper spring pressure and high rpms, not because the roller tip is heavy. The valve literally bounces off of the valve seat and it opens a little bit when it isn't supposed to at high rpms.
Check out this video. You can see the valve bouncing at about 2:30....before that you can see how the valve is deflecting at high speeds from the spring movement.
http://www.youtube.com/watch?v=cfGg15WgSEU
There are plenty of other videos on there that show valve float even with non roller tip rockers.
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I don't know a whole lot about HS, but from what I've read, people that use them like them. I haven't heard too much negative about them.
You're gonna need to find out which rockers they are and what spring pressure they are rated to handle and so forth. If you put a stiff spring on there and the rocker isn't rated high enough to handle it, you're gonna have big problems.
You're gonna need to find out which rockers they are and what spring pressure they are rated to handle and so forth. If you put a stiff spring on there and the rocker isn't rated high enough to handle it, you're gonna have big problems.
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Keep the Rollers. They don't slide back and forth on the valve tip like the stock ones do. Also just like was mentioned above, a heavy rocker doesn't create valve float. Thats all done by improper spring pressure with whatever cam you have chosen. You want a nice solid rocker for a stable valvetrain. I run Scorpions and really like them.
Brian tooley said this about stock rockers over on yellowbullet forum:
Too much spring pressure over the nose will eat up the valve tips and eventually the rocker tips. The damage usually starts by pitting the tips or rolling off the edges like you're seeing.
You MUST understand that the "scroll" that you see on the LS rocker where it contacts the valve tip runs out at about .550" lift, from there you're opening the valve with the tip end of the rocker!
When the rocker scroll is in contact with the valve tip the contact patch is fairly wide and the oil film is supporting it. Once the rocker gets out on the tip end, the contact patch gets very narrow. The oil film will not support the very narrow contact patch forever, and then eats up parts. This narrow contact patch is happening at the same time maximum spring pressure is happening, so that's a double whammy. Actually, there's a triple whammy because the rocker starts scrubbing after .550" lift, where it works like a rocking chair or gear mesh for the first .550" of lift, after that it scrubs.
For what it's worth, a LS7 rocker has more contact patch at .650" than a LS1/2/3/6 rocker has at .600"! If you do the math of a contact patch that is .020" X .200" that equals .004 sq in of area, at 471 lbs of spring pressure your resultant pressure is 117,750 PSI!
You're better off to run softer ramp rates and less spring pressure, it may make just as much power, it will be stable, and it will be durable. I use 400 lbs as a maximum number for stock rockers.
Too much spring pressure over the nose will eat up the valve tips and eventually the rocker tips. The damage usually starts by pitting the tips or rolling off the edges like you're seeing.
You MUST understand that the "scroll" that you see on the LS rocker where it contacts the valve tip runs out at about .550" lift, from there you're opening the valve with the tip end of the rocker!
When the rocker scroll is in contact with the valve tip the contact patch is fairly wide and the oil film is supporting it. Once the rocker gets out on the tip end, the contact patch gets very narrow. The oil film will not support the very narrow contact patch forever, and then eats up parts. This narrow contact patch is happening at the same time maximum spring pressure is happening, so that's a double whammy. Actually, there's a triple whammy because the rocker starts scrubbing after .550" lift, where it works like a rocking chair or gear mesh for the first .550" of lift, after that it scrubs.
For what it's worth, a LS7 rocker has more contact patch at .650" than a LS1/2/3/6 rocker has at .600"! If you do the math of a contact patch that is .020" X .200" that equals .004 sq in of area, at 471 lbs of spring pressure your resultant pressure is 117,750 PSI!
You're better off to run softer ramp rates and less spring pressure, it may make just as much power, it will be stable, and it will be durable. I use 400 lbs as a maximum number for stock rockers.
Someone out there has had a problem with all the rockers listed in this thread. They all want to blame the rocker for the problem. Long as you set up any of them correctly they will be good. I have HS on my car and they are doing great. The machine shop assembled my long block.
People are on the OEM rocker kick with trunion upgrades because most of the people who have valve float eliminate it simply by switching back to their stock rockers.
Again, I dont think your correct. A lighter system requires a less of a spring to stay in control. If you put heavy valves, or heavy rockers you then have to use a much bigger spring to compensate for the heavy parts. But if you use better and lighter parts, you dont require as heavy of a spring.