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Old 02-14-2010, 07:20 AM   #1
Nealjr
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Default Can't keep rocker arm stub bolts tight.

I bought a nice set of the bolts with the Alan wrench screw in the center but for some reason I can't get them to stay tight. I promise I've followed my valve train adjustment instructions very closely and I'm doing everything I can to avoid OVER-tightening. Whats the trick? Thanks in advance!
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Old 02-14-2010, 08:25 AM   #2
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Are you locking down the nut after you set the Allen screw where you want it? (You have to hold the Allen screw in place with a 'key' when you lock it down.)
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Old 02-14-2010, 08:31 AM   #3
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The directions I was give were roughly:
1. Adjust nut until sounds/feels correct.
2. Turn an additional 1/4.
3. Hold nut with wrench and tighten Allen screw.
4. Move on.

Are you saying #2 and #3 are switched?
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Old 02-14-2010, 09:00 AM   #4
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Tighten it down to the point where you feel like it's perfect including your 1/2 to 3/4 turn for preload (I've never used 1/4 turn). Back the nut off about 1/8 turn or so. Tighten the allen screw until it's sung, then TIGHTEN THE ALLEN SCREW AND THE POLYLOCK NUT AT THE SAME TIME. You may have to play with it a bit to get your lash perfect, but you'll get the hang of it pretty quickly. This method works like a champ and if done right, it'll lock 'em tight. If you're trying to tighten the allen set tight enough to hold 'em after you've adjusted the nut, you can't generate enough bite with just the allen set to hold 'em.

Last edited by L88Plus; 02-14-2010 at 09:04 AM.
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Old 02-14-2010, 09:27 AM   #5
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I'll give it a shot later today. Hope it solves my problem! Quick question though... what kind of upgrades can I make in this area? I've been told to switch from 1.5 rockers to 1.6. I've also read that roller rockers provide more compression which in turn increases power. Please advise.
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Old 02-14-2010, 06:35 PM   #6
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Going to a 1.6 ratio rocker will make only the slightest improvement. Roller lifters will only reduce friction load a bit. Both of those changes are expensive for any gain that you might get. For a stock [or 'near' stock] engine, those mods are only for looks (and you can't see them with the valve covers on). Save your money for a better cam with roller lifters.
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Old 02-14-2010, 11:16 PM   #7
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Take a look at the tips of your pushrods. I couldn't keep a lash on a 355ci once for more than a few hundred miles, turns out the pushrods ( type with the ball on the end ) was wearing down, actually losing material, bought some good Comp Cams pushrods and the problem was solved.

If you poly locks weren't made in China I can't see any reason why adjusting them to the desired height and then locking them with the allen bolt wouldn't hold them, been doing that for years with no problems. That's the way I do my T&D shaft rockers and they don't move, at all.

Some times you can get cheap ones and when you lock the allen bolt it actually lifts the rocker up a few thou, no big deal on a hydraulic cam but could put your lash out of whack on a solid cam.
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Old 02-14-2010, 11:25 PM   #8
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If the tops of your rocker arm studs aren't perfectly flat, you will never get a set of polylocks to hold adjustment. After confirming they are tight, you need to check your valve lash settings, and when setting the lock nut, back it off 1/8-1/4 turn, set the allen set screw then turn both the locknut and set screw toghether back to the lash point. This "digs" the set screw into the top of the rocker arm stud and locks everything solid.

One word of caution, if you perload the set screw too thight, you may back off the rocker arm stud when you try to back off the polylock for the next valve adjustment. The technique takes time to develop but, works well for me.
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Old 02-15-2010, 07:04 AM   #9
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Quote:
Originally Posted by MotorHead View Post
That's the way I do my T&D shaft rockers and they don't move, at all.
Show-off!
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Old 02-15-2010, 07:25 AM   #10
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The lash is set by the nut. So with the allen lose rotate your box end wrench to the point of correct lash. Then back off the box end wrench 1/8th or what ever it takes. Then tighten your allen down snug and tighten the box end that 1/8th or so to the previous correct lash point.

That loads the allen tighter than you could possibly do with an allen wrench. I've never had mine come loose even on race motors
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Old 02-16-2010, 07:35 PM   #11
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With everyone's help I believe I have them staying where I set them. However now I'm having trouble getting the car to run 'well'. Its hard to describe and the adjustments seem very subjective/open to interpretation. Where could I find a professional/expert locally that is trained to do this sort of thing? I'm in Tampa, FL if someone has some recommendations.

Basically pulling my hair out over this adjustment. Tried the first thing I was told which was to loosen until the clap and then tighten until they stop. Lock with an additional quarter turn. This method seems to work well enough but the idle seems rough to me. With this adjustment I can still feel a slight tapping but when I apply more pressure with the socket it seems to hit harder. Car idles easily at around 800rpm in park w/ 600ish under load. Wants to die at random times but given a little gas it seems healthy again. I've tried tightening as far as I feel safe and the car seems to idle smoother but definitely doesn't want to stay running when under load. However it'll maintain the smoothest and lowest idle in park that I've ever experiences. Needless to say I'm a little frustrated with my own towering ignorance of the matter. I've tried adjusting the idea mixture screws per the Edelbrock carb instruction manual as well as the single screw on the throttle assembly but to no avail. Currently the car is running barely tightened past the harder clapping feeling and I'm ready to buy a truck lol.


P.S. I've been messing with it so much trying to get it right I made my own tools to make things easier. I'm debating to modify them further so that I can use oil deflector clips in conjunction. They are heading to the trash anyway. :P

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Old 02-16-2010, 08:26 PM   #12
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Quote:
Originally Posted by Nealjr View Post
With everyone's help I believe I have them staying where I set them. However now I'm having trouble getting the car to run 'well'. Its hard to describe and the adjustments seem very subjective/open to interpretation. Where could I find a professional/expert locally that is trained to do this sort of thing? I'm in Tampa, FL if someone has some recommendations.

Basically pulling my hair out over this adjustment. Tried the first thing I was told which was to loosen until the clap and then tighten until they stop. Lock with an additional quarter turn. This method seems to work well enough but the idle seems rough to me. With this adjustment I can still feel a slight tapping but when I apply more pressure with the socket it seems to hit harder. Car idles easily at around 800rpm in park w/ 600ish under load. Wants to die at random times but given a little gas it seems healthy again. I've tried tightening as far as I feel safe and the car seems to idle smoother but definitely doesn't want to stay running when under load. However it'll maintain the smoothest and lowest idle in park that I've ever experiences. Needless to say I'm a little frustrated with my own towering ignorance of the matter. I've tried adjusting the idea mixture screws per the Edelbrock carb instruction manual as well as the single screw on the throttle assembly but to no avail. Currently the car is running barely tightened past the harder clapping feeling and I'm ready to buy a truck lol.


P.S. I've been messing with it so much trying to get it right I made my own tools to make things easier. I'm debating to modify them further so that I can use oil deflector clips in conjunction. They are heading to the trash anyway. :P

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Read this article: Everything you need to know on adjusting your valves.

http://www.corvetteforum.com/techtip...=116&TopicID=3


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Old 02-16-2010, 08:46 PM   #13
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Quote:
Originally Posted by Nealjr View Post
1. Adjust nut until sounds/feels correct.
This doesn't really make any sense We're trying to find zero lash + preload, not a "sound".

Quote:
Originally Posted by thoyer View Post
Read this article: Everything you need to know on adjusting your valves.

http://www.corvetteforum.com/techtip...=116&TopicID=3
This is the solution to the problem as a straightforward way to find zero lash and correctly set preload.

Note that Lars asks folks not to post his papers but rather to email him for them as he constantly updates them. V8FastCars@msn.com

Last edited by billla; 02-16-2010 at 08:48 PM.
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Old 02-16-2010, 09:33 PM   #14
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Wow that makes it sound so much easier!
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Old 02-16-2010, 10:03 PM   #15
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If the rockers always seem to be loose, another thing that could be happening is that the studs are pulling out. Do you have pressed in studs.? If so, check to see if they all are the same height.
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Old 02-16-2010, 11:00 PM   #16
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Quote:
Originally Posted by Nealjr View Post
Wow that makes it sound so much easier!
I don't know that it's "easy" but it's straightforward and you're going to flatten a lobe if you keep going about it the way you are.

Good luck!
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Old 02-17-2010, 07:29 AM   #17
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I don't care for spinning the pushrod between your fingers, I always rattle 'em up and down and tighten 'em until that's gone, that's my zero lash point. I've had pushrods you could spin with your fingers with the valve well off the seat.
I've watched old roundy-rounders tighten 'em all the way down, then loosen 'em a full turn. They claimed it got 'em 500rpm more before any signs of valve float.
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Old 02-17-2010, 07:32 PM   #18
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Quote:
Originally Posted by Solid LT1 View Post
If the tops of your rocker arm studs aren't perfectly flat, you will never get a set of polylocks to hold adjustment.

I took my rocker arm studs to a machine shop and had them grind a good flat surface into the end of the bolt. End of problem.
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Old 02-17-2010, 09:31 PM   #19
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Quote:
Originally Posted by L88Plus View Post
Show-off!
That's the way I do my gold plated T&D shaft rockers and they don't move, at all.
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Old 02-18-2010, 11:03 AM   #20
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I was going to say something about people that cut up valve covers and or attempt to set valve lash on running motors

But my Mom said: "That if you can't say anything nice you should not say anything!" .
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Old 02-18-2010, 11:03 AM
 
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