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Old 04-14-2021, 09:11 AM   #29
KingLT1


 
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Originally Posted by 17camaroSS View Post
The factory rocker will last at 7K+ rpm with a trunnions upgrade like CHE. Brandon Hill run them, Brady ran them in his car, along with a lot of other guys/gals out there spinning their cars up above that. Once you going to an aftermarket rocker you’re adding more weight over the valve which isn’t the best thing. Also, Gwatney did a test with stock and aftermarket rockers. The factory rocker with a trunnion upgrade made more power and was more stable at higher rpm than the aftermarket stuff.
It really isn't RPM specific, it has more to do with the cam profile and lift. Anything much over .630 lift and the stock rocker arm starts to side load the valve. That isn't good for longevity but with the correct type of valve guide will help. I agree for most setups stock rockers work fine. Weight over the valve is a issue but there are ways to address that. It just depends on the setup... for a .700 lift solid roller that needs some serious spring with link bar lifters, going shaft mount that are fully adjustable for precise preload adjustment is probably a better choice. A Hydraulic cam under .630 lift with a decent drop in lifter, Stock rockers seem to work fine and have since 1997 when the LS1 was introduced.
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Old 04-14-2021, 04:37 PM   #30
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Originally Posted by KingLT1 View Post
It really isn't RPM specific, it has more to do with the cam profile and lift. Anything much over .630 lift and the stock rocker arm starts to side load the valve. That isn't good for longevity but with the correct type of valve guide will help. I agree for most setups stock rockers work fine. Weight over the valve is a issue but there are ways to address that. It just depends on the setup... for a .700 lift solid roller that needs some serious spring with link bar lifters, going shaft mount that are fully adjustable for precise preload adjustment is probably a better choice. A Hydraulic cam under .630 lift with a decent drop in lifter, Stock rockers seem to work fine and have since 1997 when the LS1 was introduced.
I completely agree
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Old 04-14-2021, 08:00 PM   #31
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Originally Posted by KingLT1 View Post
It really isn't RPM specific, it has more to do with the cam profile and lift. Anything much over .630 lift and the stock rocker arm starts to side load the valve. That isn't good for longevity but with the correct type of valve guide will help. I agree for most setups stock rockers work fine. Weight over the valve is a issue but there are ways to address that. It just depends on the setup... for a .700 lift solid roller that needs some serious spring with link bar lifters, going shaft mount that are fully adjustable for precise preload adjustment is probably a better choice. A Hydraulic cam under .630 lift with a decent drop in lifter, Stock rockers seem to work fine and have since 1997 when the LS1 was introduced.
So it seems like I should be getting the machine shop to install better valve guides along with the seats? I have never seen anyone selling "better" or "upgraded" valve guides for even LS stuff much less valve seats.
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Old 04-15-2021, 08:31 AM   #32
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So it seems like I should be getting the machine shop to install better valve guides along with the seats? I have never seen anyone selling "better" or "upgraded" valve guides for even LS stuff much less valve seats.
Powdered metal guides are typically recommended for stock rockers. Bronze guides for full roller rockers. There have been plenty of cases of premature guide wear using stock rockers with bronze guides and really high lift cams.
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Perf. times- 1.75 60ft 10.5 @135 1/4mi Dragy Approved...No prep Full weight on 20's.
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Old 04-18-2021, 08:50 PM   #33
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Originally Posted by KingLT1 View Post
Powdered metal guides are typically recommended for stock rockers. Bronze guides for full roller rockers. There have been plenty of cases of premature guide wear using stock rockers with bronze guides and really high lift cams.
Thanks King, CHE did reply back to me and recommended bronze seats. I don't know if he was recommending bronze for the exhaust seat also or not, could you even run bronze type alloy on the exhaust side?

Do you think the trunnion upgrade is doing anything to help valve deflection and stability with big cams? Or is it just more stuff for shops to sell? It would seem it would only be important on maybe the GEN IV stuff with the offset rocker arms and help them be stiffer?
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Old 04-18-2021, 09:35 PM   #34
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Trunnion upgrade is to keep from potentially having a rocker fail and spill needle bearings down into the engine. Other then that I don't think they do anything else. It's more of a preventative mod then anything else.
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Perf. mods-Whipple 2.9/Fuel System/LT5 TB/Rotofab Big Gulp/E60/Cat Deletes/NPP Axle back
Perf. times- 1.75 60ft 10.5 @135 1/4mi Dragy Approved...No prep Full weight on 20's.
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Old 04-19-2021, 05:51 PM   #35
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Originally Posted by KingLT1 View Post
Trunnion upgrade is to keep from potentially having a rocker fail and spill needle bearings down into the engine. Other then that I don't think they do anything else. It's more of a preventative mod then anything else.
I was talking to CHE trying to get seats and he was reccommending them, but then again he was bashing E85 pretty hard and arguing that it has no lubricity. He also said I should run no valve seal I think he said on the exhaust side, either way that sounds like it would make the valve coking issue worse haha I mean.

At this point I think I should probably just buy aftermarket heads, its just hard to do seeing that its going to be over 3000 probably and I don't see where you are gaining anything besides having some more material in some places. It would be different if I could get smaller combustion chambers to help with compression.
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