C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Push rod guide plates or not?

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Old Apr 19, 2020 | 06:00 PM
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Default Push rod guide plates or not?

1989 stock

I’m confused. I’ve read that L98 aluminum heads have hardened push rods and use guide plates, and I’ve read they don’t use guide plates. My heads do have guide plates, but was told they are there only because they were used at assembly Anyone really know the answer?
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Old Apr 20, 2020 | 04:24 AM
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Anyone?
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Old Apr 20, 2020 | 04:29 AM
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Guide plates only for assembly. Alignment is held by rocker arms. Don’t know the answer about plates or rods being hardened.
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Old Apr 20, 2020 | 12:52 PM
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Originally Posted by mlm0
My heads do have guide plates, but was told they are there only because they were used at assembly Anyone really know the answer?
Originally Posted by Siveck
Guide plates only for assembly. Alignment is held by rocker arms.
That is the truth. Neither the "guide plate" nor the pushrod in a stock L98 are hardened. If you tried to run the engine using the stock guide plate, as a guide plate, it and the push rod would self destruct in minutes. Also, the stock "guide plate" has WAY too much clearance to function correctly as a real guide plate.

Siveck is right that the plate is only there for assy, and the tip or the rocker overlaps the valve stem tip, thereby aligning the rocker.




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Old Apr 20, 2020 | 01:53 PM
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I do not believe you have hardened push rods and for that reason you need to use self aligning rockers whether you have guide plates installed or not. That is my understanding.
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Old Apr 21, 2020 | 08:53 AM
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Think i heard somewhere that (non self aligning) rockers with hardened guideplates are waaay better than self aligning rocking arms

Last edited by dizwiz24; Apr 21, 2020 at 08:53 AM.
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Old Apr 21, 2020 | 11:34 AM
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Originally Posted by dizwiz24
Think i heard somewhere that (non self aligning) rockers with hardened guideplates are waaay better than self aligning rocking arms
They are, as you move up the RPM range. For an '89 TPI (the OP's car) it ain't gonna matter either way. Which ever is cheaper/easier is better than good enough.
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Old Apr 22, 2020 | 03:33 PM
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Thanks to all

Mike
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Old Jul 20, 2020 | 09:58 PM
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But
in my 57 chevy truck there lives an 89 corvette L98 with a 4+3.
i have been using comp cams roller tipped rockers with the factory guide plates for about 8 years.
recently i switched to Harlan Sharp 1.6 full roller rockers.
still no problems not using self aligned rockers.
do your own testing. Be a myth buster.
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Old Jul 21, 2020 | 11:24 PM
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Originally Posted by coupeguy2001
But
in my 57 chevy truck there lives an 89 corvette L98
still no problems not using self aligned rockers.
do your own testing. Be a myth buster.
Here’s what will happen when you run non self aligning rockers with factory 113 guide plates. BUSTED! 😂

Now running Manley hardened guide plates and pushrods.
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