Why am I breaking rockers still??? WTF!
10-18-2008, 10:22 AM
#1
Staging Lane
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Why am I breaking rockers still??? WTF! I have hade two Scorpion roller rockers fail where the pushrod indexes the cup and blown holes through the body of the rocker with the pushrod. I checked wipe and valvetrain geometry & pushrod length and everything seems fine. I upgraded to YellaTerra UL shaft rockers and figured I was good to go. I drove the car from Minneapolis, MN to Huntsville, AL 2 days ago and experienced a Yella Terra Failure (failed the same way). I put an old pair of Scorpion rockers in to temporarily get me to AL. Now I have a 1000 mile trip home and I'm pretty ******* sure I 'll have another failure somewhere along the way. Here are the facts:
1) The car runs fine for 600-800 miles just fine...then a rocker pops.
2) The effected rocker failures have always been a different one...both exhaust & intake
3) All failures are on the passenger side of the motor
4) After a failed rocker is replaced, engine runs just fine for another 600-800 miles and then it will usually pop another godamned rocker. (see #1)
5) I race my car on rare occasions and I've never had a problem reving the motor to 7000 RPM, dragging & roadracing. These failures only happen when I'm cruising along at 2-2500 RPM like an old blue haired lady! You'd think they would fail when your pounding the **** out of it for Christ's sake!
I'm not exactly sure what the ****'s happening here but it is obviously starting to **** me off a little bit. I need a grab bag full of extra rockers for a road trip in case one pops. That's no way to travel! I have a problem that only happens intermittently and seems to cause the pushrod to jump further than normal resulting in a collision with the backside of the rocker and subsequent damage to the cup & rocker body. The only 2 things I think would cause this would be sticking/failing lifters (but they are new LS7 lifters) and deck heights on either the block or heads that don't match.
Any advice or experience would be appreciated.
1) The car runs fine for 600-800 miles just fine...then a rocker pops.
2) The effected rocker failures have always been a different one...both exhaust & intake
3) All failures are on the passenger side of the motor
4) After a failed rocker is replaced, engine runs just fine for another 600-800 miles and then it will usually pop another godamned rocker. (see #1)
5) I race my car on rare occasions and I've never had a problem reving the motor to 7000 RPM, dragging & roadracing. These failures only happen when I'm cruising along at 2-2500 RPM like an old blue haired lady! You'd think they would fail when your pounding the **** out of it for Christ's sake!
I'm not exactly sure what the ****'s happening here but it is obviously starting to **** me off a little bit. I need a grab bag full of extra rockers for a road trip in case one pops. That's no way to travel! I have a problem that only happens intermittently and seems to cause the pushrod to jump further than normal resulting in a collision with the backside of the rocker and subsequent damage to the cup & rocker body. The only 2 things I think would cause this would be sticking/failing lifters (but they are new LS7 lifters) and deck heights on either the block or heads that don't match.
Any advice or experience would be appreciated.
10-18-2008, 12:24 PM
#2
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I assume you've had the pushrods out to make sure there's no contact with the head (obvious, but hey). I know you said you've checked geometry, but are you 100% sure you've got the lifter preload correct and/or are not experiencing ANY binding on the springs? I'd definitely get the covers off, start rotating the engine by hand and REALLY take a detailed look at what's going on. Good luck.
10-18-2008, 04:53 PM
#5
Is your preload excessive? I installed a set of Scorpions in a Silverado over a year ago(over 20K miles) with no problems and no call backs. The owner loves them. The lift using a 1.8 ratio rocker with a cam ground for 1.7 is an effective 575(ballpark). You're doing something wrong.
