Roller rocker hits rocker stud nut
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 2,158
Likes: 9
From: N.E. WA
Roller rocker hits rocker stud nut
I am installing new roller rockers on my Lt1 and when I attempt to adjust the rocker, the bottom of the fulcrum hits the rocker stud nut. I am using guide plates under my stock studs and non self-alignment RR's. I am using a stock height pushrod, but the alignment isn't necessarily the problem. I had crane gold 1.5's on before and noticed that one of them had hit also. Do they have different studs with smaller heads, or do I have to step up the pushrod height?
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 2,158
Likes: 9
From: N.E. WA
Re: Roller rocker hits rocker stud nut (Nathan Plemons)
I'm wondering if anyone has had to machine the surfaces that the guide plate sits on. I effectively move the rocker stud up the thickness of the guide plate.
Race Director
Joined: May 2001
Posts: 14,165
Likes: 9
Re: Roller rocker hits rocker stud nut (ANTI VENOM)
Well the LT1 Vettes have guideplates from the factory. Aftermarket ones aren't any thicker than that. I'm running comp cams guideplates with 7/16 studs and scorpion rockers with no problems. I used to use the same guideplates with a set of crane golds with my 3/8 studs.
Take a look at the size of these rockers, they don't contact anything.
http://www.wku.edu/~nathan.plemons/g...te/rockers.jpg
If this is part of your stroker project, is it possible that the wrong length valves were installed in the heads? :confused:
Take a look at the size of these rockers, they don't contact anything.
http://www.wku.edu/~nathan.plemons/g...te/rockers.jpg
If this is part of your stroker project, is it possible that the wrong length valves were installed in the heads? :confused:
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 2,158
Likes: 9
From: N.E. WA
Re: Roller rocker hits rocker stud nut (Nathan Plemons)
This isn't on my stoker engine. It's on my 92. I didn't know that the LT1's came with guide plates. I thought they had self aligning rockers and no plates. When I got my 92, the roller rockers were already on it, but it has undergone a rebuild since then. I've run this setup for 1000's of miles, I was just upgrading to 1.65 RR's and noticed the problem with the new RR's. I'm sure we'll get to the bottom of this.
Pro
Joined: Jan 2003
Posts: 669
Likes: 0
From: memphis tn
Re: Roller rocker hits rocker stud nut (65Z01)
are you talking about the rockers sitting too low on the stud and hitting the hex part of the stud , or is the rocker hitting the poly lock?
if its hitting the base of the stud, you may have to machine it down a bit. comp cams sells a tool to do this, however you need to find or make some type of set screw as the hole the stud goes in goes straight thru to the intake port.
if its hitting the base of the stud, you may have to machine it down a bit. comp cams sells a tool to do this, however you need to find or make some type of set screw as the hole the stud goes in goes straight thru to the intake port.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Re: Roller rocker hits rocker stud nut (ANTI VENOM)
Not knowing who originally set up the valve train geometry, and since one of the other rockers was also hitting, I'd first check the valve train geometry.
I'd get a pushrod length checker and use it to make sure that your current pushrods are the correct length.
Jake
I'd get a pushrod length checker and use it to make sure that your current pushrods are the correct length.
Jake
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 2,158
Likes: 9
From: N.E. WA
Re: Roller rocker hits rocker stud nut (neverendingproject)
Yes, the rocker sits to low on the stud and hits the hex part of the stud. I set up the valvetrain with the other RR's and valves. Everything was fine with the exception of the one rocker. I've also never heard of this happening to anyone else with an LT1. I understand what a longer pushrod would do, but I can't really tell how they would work until I can actually adjust a rocker arm and see how the roller pattern is on the valve stem.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Re: Roller rocker hits rocker stud nut (ANTI VENOM)
Have you tried swapping different rockers onto that one problem stud to see if, perhaps, it's the 'rocker', not the stud, etc.?
The purpose of of the pushrod length checking tool is to determine what length pushrod you need. The least expensive one, I believe it's a Mr. Gasket, doesn't call for the use of the rocker arm to determine the correct pushrod length. The tool, itself, shows you if your current pushrods are too long, too short or right on.
Jake
The purpose of of the pushrod length checking tool is to determine what length pushrod you need. The least expensive one, I believe it's a Mr. Gasket, doesn't call for the use of the rocker arm to determine the correct pushrod length. The tool, itself, shows you if your current pushrods are too long, too short or right on.
Jake
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Re: Roller rocker hits rocker stud nut (JAKE)
Just a thought, you aren't, by any chance, trying to install the rocker with the recess downward are you?
Someone else on the Forum made that mistake recently.
Jake
Someone else on the Forum made that mistake recently.
Jake
Large Impressive Member
Joined: Jul 2003
Posts: 65,811
Likes: 71
From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Re: Roller rocker hits rocker stud nut (Nathan Plemons)
Well the LT1 Vettes have guideplates from the factory.
[Modified by Corvette Kid NC, 10:55 PM 5/7/2004]
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 2,158
Likes: 9
From: N.E. WA
Re: Roller rocker hits rocker stud nut (Corvette Kid NC)
Jake, are you talking about the recess for the poly locks? I have them turned correctly and I have swapped rockers and studs around and they just don't work. I haven't done it yet, but I bet if i took off the guide plate, I wouldn't have a clearance issue. I just wonder why nobody else has run into this. My combo is a pretty mild and popular setup. Lift will only be in the 560's, but at this point, it has nothing to do with it. The rockers don't seem to be built any differently than the previous ones, they just have a different ratio.
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 2,158
Likes: 9
From: N.E. WA
Re: Roller rocker hits rocker stud nut (ANTI VENOM)
I did some checking and found that Manley (and probably others) make a rocker stud boss cutter. That makes me think that there is reason to cut them down. I will have to investigate this further. My car sits again in it's auto cocoon next to the never ending project car. My 92 is red and it's fitting, since it's the DEVIL!
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 2,158
Likes: 9
From: N.E. WA
Re: Roller rocker hits rocker stud nut (ANTI VENOM)
Ok, I took off the guide plate and adjusted an in/ex combo and then looked at where they were "wearing" on the valve stem. The pattern starts at about the center of the stem and works its way away from the pushrod, or toward the header. I thought that meant that I needed a shorter pushrod, wich would make the rocker arm to stud contact even worse with the guideplate installed.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Re: Roller rocker hits rocker stud nut (ANTI VENOM)
The rocker arm roller does just that, it rolls from inboard, across the center, to outboard and then back again.
With the lifter on the base circle (heel) of the camshaft lobe - valve closed -, the roller should be slightly inboard of the center of the valve stem tip.
As the engine is turned over, at mid valve lift, the roller should be centered on the valve stem tip.
As you continue to turn the engine over, the roller should travel to a point outboard of the valve stem center at full valve lift.
Then, as the valve begins to close, the roller should begin to move inboard again.
So it goes, inboard, center, outboard, center, inboard, etc.
Jake
With the lifter on the base circle (heel) of the camshaft lobe - valve closed -, the roller should be slightly inboard of the center of the valve stem tip.
As the engine is turned over, at mid valve lift, the roller should be centered on the valve stem tip.
As you continue to turn the engine over, the roller should travel to a point outboard of the valve stem center at full valve lift.
Then, as the valve begins to close, the roller should begin to move inboard again.
So it goes, inboard, center, outboard, center, inboard, etc.
Jake
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: Roller rocker hits rocker stud nut (JAKE)
The end of the valve stem and the end of the push rod dictate how high up from the head, the fulcrum will ride on the stud. Moving the stud up or down will make no difference in where the rocker arm wants/needs to be, relative to the head.
The roller tip travels in an arc. If the fulcrum of the rocker arm is above the plane that is 90* to and even with the valve stem, the arc will be at the top of the second quadrant. The tip will move from the outside of the valve stem, in wards. If the fulcrum is below that plane the tip will travel in the bottom of the first quadrant and run from the inside to the outside.
The maximum travel of a "lever", and a tangent to the circle (arc) that the tip follows is greatest when they are at 90* to one another. Ideal rocker geometry would have the rocker arm contacting the center of the valve stem at 1/2 lift. At full lift the contact point would be exactly the same distance past the center point as it started ahead of the center point. It would make no difference whether the arm swept in wards or out wards to achieve this. That would maximize the the time at, and or closest to the 90* position and result in the highest lift possible with a given cam and rocker ratio.
Clear as mud???
RACE ON!!!
The roller tip travels in an arc. If the fulcrum of the rocker arm is above the plane that is 90* to and even with the valve stem, the arc will be at the top of the second quadrant. The tip will move from the outside of the valve stem, in wards. If the fulcrum is below that plane the tip will travel in the bottom of the first quadrant and run from the inside to the outside.
The maximum travel of a "lever", and a tangent to the circle (arc) that the tip follows is greatest when they are at 90* to one another. Ideal rocker geometry would have the rocker arm contacting the center of the valve stem at 1/2 lift. At full lift the contact point would be exactly the same distance past the center point as it started ahead of the center point. It would make no difference whether the arm swept in wards or out wards to achieve this. That would maximize the the time at, and or closest to the 90* position and result in the highest lift possible with a given cam and rocker ratio.
Clear as mud???
RACE ON!!!
Race Director
Joined: May 2001
Posts: 14,165
Likes: 9
Re: Roller rocker hits rocker stud nut (Corvette Kid NC)
Well the LT1 Vettes have guideplates from the factory.
Why they are there is a good question indeed. Since the rockers are self aligning and the pushrods don't actually touch them, who knows? I've heard it helped with engine assembly? Who knows. All I know is that mine are long gone in favor of real guideplates and hardened pushrods.
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 2,158
Likes: 9
From: N.E. WA
Re: Roller rocker hits rocker stud nut (Nathan Plemons)
Ya, mine pattern starts at center and goes outward. It never goes inward of center. I realize that moving the stud up or down doesn't move the rocker up or down, but it does move the stud nut (where contact is made) down and away from the rocker arm.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: Roller rocker hits rocker stud nut (ANTI VENOM)
...but it does move the stud nut (where contact is made) down and away from the rocker arm.
A sufficiently longer push rod could put the roller tip at, or slightly inboard of it's furthest point of travel, now, and have it traverse inward as the valve opens. It would take some trial and error with an adjustable push rod to get it right.
Other solutions include the shortening of the stud pedistal, as you suggested. Possibly trimming the the hex portion of the stud with a Dremmel tool, for clearence? Or going to self aligning rockers and NO plates. Good luck, and...
RACE ON!!!