LT1-LT4 Modifications 1993-97 Gen II Small Block V8

What caused this to break???

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Old Jul 24, 2009 | 05:31 PM
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Default What caused this to break???

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Old Jul 24, 2009 | 05:34 PM
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Did you measure for proper pushrod length?
Did you adjust that rocker properly for zero lash?
Is it NSA or SA?

Hopefully all you messed up was a rocker and nothing else.
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Old Jul 24, 2009 | 05:35 PM
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damn, another one bites the dust this week
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Old Jul 24, 2009 | 05:47 PM
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Originally Posted by ss.slp.ls1
Did you measure for proper pushrod length?
Did you adjust that rocker properly for zero lash?
Is it NSA or SA?

Hopefully all you messed up was a rocker and nothing else.
Yep went through the whole gambit of correcting for proper geometry as well as setting 1/2 turn past zero lash. They are NSA and I went with guide-plates with CC High Tech pushrods. Thankfully the pr wasn't bent, but the the valve locks did get a bit of wear, nothing too bad. I just don't know what would cause this??
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Old Jul 24, 2009 | 05:54 PM
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Originally Posted by MDR
Yep went through the whole gambit of correcting for proper geometry as well as setting 1/2 turn past zero lash. They are NSA and I went with guide-plates with CC High Tech pushrods. Thankfully the pr wasn't bent, but the the valve locks did get a bit of wear, nothing too bad. I just don't know what would cause this??
What brand guideplates? Was there any excessive wear showing the pushrod rubbing on the guideplate?
Any damage to the valve stem?
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Old Jul 24, 2009 | 06:41 PM
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Originally Posted by ss.slp.ls1
What brand guideplates? Was there any excessive wear showing the pushrod rubbing on the guideplate?
Any damage to the valve stem?
Well I'm not sure what brand the guide plates are and the pushrods do have some wear but nothing too bad, just some of the black coating wearing off. The valve stems were flat and true, no rounding or mushrooming. What is the correct ID for the guide plates if using 5/16 pushrods? I have another set of guideplates and they seem to fit a little snugger yet they are twice as thick. Could the difference in thickness be offset with preloading the lifters to 3/4 turn instead of 1/2?
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Old Jul 24, 2009 | 06:57 PM
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Originally Posted by MDR
Well I'm not sure what brand the guide plates are and the pushrods do have some wear but nothing too bad, just some of the black coating wearing off. The valve stems were flat and true, no rounding or mushrooming. What is the correct ID for the guide plates if using 5/16 pushrods? I have another set of guideplates and they seem to fit a little snugger yet they are twice as thick. Could the difference in thickness be offset with preloading the lifters to 3/4 turn instead of 1/2?
You don't change the preload depending on what guideplate you use. It jsut means that the rocker are stud will sit slightly higher in relation to the head and rocker. Nothing changes. I use Trickflow guideplates without issue and I also have Comp Pro Mags. Maybe it was a fluke, I'd contack Comp and see what they say.
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Old Jul 24, 2009 | 07:12 PM
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If you used the wrong guideplates and MOST of them are wrong then it causes weird side loading which is my best guess for what would cause that.
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Old Jul 24, 2009 | 08:17 PM
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Originally Posted by 96capricemgr
If you used the wrong guideplates and MOST of them are wrong then it causes weird side loading which is my best guess for what would cause that.
Do you happen to know what is the correct diameter for the pushrod slot if using a 5/16 pushrod?
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Old Jul 24, 2009 | 09:47 PM
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Not off hand BUT that is not the detail I meant was wrong on most. The LT1 valve spacing is a little different than most other smallblocks. Using standard guideplates the rockers do not sit square and centered on the valve. That is why I use Isky adjustables.
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Old Jul 25, 2009 | 10:30 AM
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Originally Posted by 96capricemgr
Not off hand BUT that is not the detail I meant was wrong on most. The LT1 valve spacing is a little different than most other smallblocks. Using standard guideplates the rockers do not sit square and centered on the valve. That is why I use Isky adjustables.
I did notice that the spacing on the pushrods did seem to angle the rockers just slightly which I dismissed as normal. I think I'm going to get the adjustable plates to be on the safe side. Do you have any advice on adjusting them?
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Old Jul 25, 2009 | 10:54 AM
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Damn I broke one also last week.. well, at least I found it last week and now the motor is in the spare bedroom..
I had to have my TFS guide plates machined to get the correct geometry.
My guess its it was faulty rocker like mine.

Last edited by AChotrod; Jul 25, 2009 at 11:30 AM.
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Old Jul 25, 2009 | 11:47 AM
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Damn guys that sucks But I just wanted to tell AC the bit about the engine in the spare bedroom cracked me up man!
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Old Jul 25, 2009 | 12:34 PM
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LOL! I have my 355 in the Living room
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Old Jul 25, 2009 | 04:51 PM
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[QUOTE=AChotrod;11963279]
I had to have my TFS guide plates machined to get the correct geometry.
QUOTE]

Man that's a real failure right there, sorry about your luck. I ordered a replacement rocker but now I'm wondering how often these things are breaking? What exactly did the machine shop do to the guide plates?
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Old Jul 25, 2009 | 04:56 PM
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Does anyone know what is the correct spacing for the pushrod slot in the guide plate? I measured 2" from valve stem to valve stem but the slots in my guide plates are around 1 3/4"? I thought that the rocker arm should be square and centered over the valve?
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Old Jul 25, 2009 | 09:19 PM
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IMO most of the Comp failures are CAUSED by a problem in the engine. In your case I think you have shown that you had the wrong guideplates.
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Old Jul 26, 2009 | 02:06 AM
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maybe too much spring pressure? i doubt guidplates would cause that. or maybe just another sign of comp cams superior quality.
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Old Jul 26, 2009 | 06:29 AM
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Those rockers are fine with solid roller cams. I don't see spring pressure as an issue.

I also think it important to say that the pin slid sideways, the rocker came apart more than "broke". To me I think the improper guideplate causee sidelaod slowely working the pin to the side.
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Old Jul 26, 2009 | 10:52 AM
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Would GM guideplates work? Im putting promags on my car at the moment, and would rather not break a rocker.
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