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zz4 rail rocker replacement?

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Old Aug 25, 2007 | 02:51 PM
  #1  
sweeneyuk's Avatar
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From: London
Car: 91 Z28 350tpi
Engine: 350tpi starting point
Transmission: 700r4
Axle/Gears: stock
zz4 rail rocker replacement?

I have some zz4 heads off a 91 vette & want to replace the rail rockers known as self aligning rockers with some roller rockers.

What i need to know is can i use ordinary roller rockers so long as i fit hardened guide plates or are the valve stems longer with the self aligning style rockers?

I have hardened guide plates & noticed the self aligning roller rockers are more expensive than the non self aligning.

is one method better than the other? i.e guide plates vs self aligning roller rockers?

also can any recommend a reasonably priced set?

thanks
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Old Aug 25, 2007 | 03:08 PM
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Car: '88 Trans Am
Engine: 5.7L TPI
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Axle/Gears: 3.27
Re: zz4 rail rocker replacement?

You will need:
hard pushrods up to 120.00
NSA roller rockers narrow body(i preferr 1.6s) for a little more valve lift 160.00-300.00
you already have guide plates
about 2 hours of labor
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Old Aug 25, 2007 | 04:16 PM
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From: Calgary, AB, Canada
Car: 1982 Trans-Am
Engine: 355 w/ ported 416s
Transmission: T10, hurst shifter
Axle/Gears: 10 bolt, true-trac, 3.73
Re: zz4 rail rocker replacement?

I'd just leave the self aligning rockers. You're not gaining anything by going to normal non SA rockers.
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Old Aug 25, 2007 | 04:36 PM
  #4  
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From: London
Car: 91 Z28 350tpi
Engine: 350tpi starting point
Transmission: 700r4
Axle/Gears: stock
Re: zz4 rail rocker replacement?

is there more valve stem protruding past the spring when sa rockers are used?

how can i tell if i can use sa rockers?

cant tell if the machine shop replaced the valves as i also paid him to fit guide plates before i found out that they are not needed with sa rockers.
he didnt seem too clued up about rail tip rockers & i only found out after researching on this site.

I've not been able to get back in touch with thw machine shop who did the work & its a little difficult to pay a visit as i'm in the uk.

thanks guys
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Old Aug 25, 2007 | 04:43 PM
  #5  
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Car: '88 Trans Am
Engine: 5.7L TPI
Transmission: Slushbox
Axle/Gears: 3.27
Re: zz4 rail rocker replacement?

SA rockers make noise can cause false knock if you are EFI the best safest design is NSA.
check posts about rockers www.ls1tech.com
www.camaroz28.com plenty answers there
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Old Aug 25, 2007 | 04:56 PM
  #6  
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From: Calgary, AB, Canada
Car: 1982 Trans-Am
Engine: 355 w/ ported 416s
Transmission: T10, hurst shifter
Axle/Gears: 10 bolt, true-trac, 3.73
Re: zz4 rail rocker replacement?

SA rockers make noise can cause false knock if you are EFI the best safest design is NSA.
I'm sorry, but that's ridiculous.

is there more valve stem protruding past the spring when sa rockers are used
No


Valves need A (singular) method of guiding the pushrods.

-Slots in cylinder head
-Guide plates
-SA rockers

Pick any one and enjoy. If your heads have slots where the pushrods come through (and not big gaping circular holes), then you're done, use non SA rockers.
If they have holes you either need the guide bosses machined for guide plates, and non-SA rockers, of go simple, and use SA rockers.
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Old Aug 25, 2007 | 06:03 PM
  #7  
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Engine: 5.7L TPI
Transmission: Slushbox
Axle/Gears: 3.27
Re: zz4 rail rocker replacement?

if that is soo rediculous why did chevrolet instal a less sensative knock module in the pcm to cancel the added valvetrain noise due to the SA rockers in the LT4 engine along with composite valve covers instead of metal?
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Old Aug 25, 2007 | 09:38 PM
  #8  
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Car: 91 RS
Engine: 350 vortec
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Re: zz4 rail rocker replacement?

so if the SA rockers of say a 062 head made more "noise" than say 416's? actually it seems to be they replaced the rockers on the LT4 due to galling of the ***** at high RPMS they went with modified comp roller rockers which are forged AL and produce more valve train noise than the stamped steel... and for the composite covers... who knows maybe they were cheaper...
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Old Aug 25, 2007 | 09:51 PM
  #9  
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From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Originally Posted by sweeneyuk
I have some zz4 heads off a 91 vette & want to replace the rail rockers known as self aligning rockers with some roller rockers.
That doesn't sound right. I was under the understanding that they used soft guide plates.

But, wouldn't be the first time I was wrong.
----------
Originally Posted by 92droptopws6
if that is soo rediculous why did chevrolet instal a less sensative knock module in the pcm to cancel the added valvetrain noise due to the SA rockers in the LT4 engine along with composite valve covers instead of metal?
The earth's temperature has been rising since cell phone use has become common place. Think those things are related?

Last edited by five7kid; Aug 25, 2007 at 09:54 PM. Reason: Automerged Doublepost
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Old Aug 26, 2007 | 01:01 AM
  #10  
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From: Calgary, AB, Canada
Car: 1982 Trans-Am
Engine: 355 w/ ported 416s
Transmission: T10, hurst shifter
Axle/Gears: 10 bolt, true-trac, 3.73
Re: zz4 rail rocker replacement?

I'm glad someone beat me to it Five7, and with a more intelligent quip than I would come up with as well.
When I swapped to SA rockers on my engine there was no noise change, that my in-sensitive ears could pick up at least. Theoretically I can't see why there would be either, the mechanics of the movement don't change to a method that would be "louder".
The gist of my post was for sweenyuk. There needs to be one method. None are really better than the other per se, although guideplates are most common on hot rodder engines - take that as you will.
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