Ls3 with 1.8 rockers install
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From: Baton Rouge LA
Ls3 with 1.8 rockers install
I am considering installing 1.8 ratio rockers (likely yella terra ultra lites) in my stock engine, stock cam LS3 (I have headers, intake, tune). I know this will require upgrading springs. I have a couple questions. Has anyone done this swap and and have any issues? Is there anything I need to watch out for or pay particular attention to when installing yella terra ultra lite rockers or springs (remember I haven't done this before)?
From what I've read this can be worth 15-20 hp. And no I am not looking to do or considering a cam. Thanks for the help
From what I've read this can be worth 15-20 hp. And no I am not looking to do or considering a cam. Thanks for the help
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Joined: Nov 2007
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From: Baton Rouge LA
Also I've found many sites selling yella terra 1.85 rockers YT6685 for the LS3 although yella terra doesn't list them in the ls3 area on their site. I've asked them about this application but haven't gotten a response yet. Anyone have experience with yella terra 1.85's on ls3? Or know that it wouldn't work?
Melting Slicks
Joined: Jun 2006
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From: Miami Florida
You can just bolt them on and no need to change springs with the stock cam as you will be getting only though important .036 thousands extra lift if using the 1.8 and .054 with the 1.85s the heavier load springs will end up consuming half your gains if you went that route.
Le Mans Master
Joined: Oct 2014
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From: Atlanta GA
You can just bolt them on and no need to change springs with the stock cam as you will be getting only though important .036 thousands extra lift if using the 1.8 and .054 with the 1.85s the heavier load springs will end up consuming half your gains if you went that route.
I lot of posts I am reading state that the 1.8 will cause valve float ... that is why I was looking at springs
Dave
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From: Baton Rouge LA
You have to change springs with 1.8 or 1.85 rockers even with stock cam. Stock springs are only rated for 0.550 lift, if you increase lift with rockers and keep stock springs you risk spring failure. From a spring point of view changing rockers is the same as a higher lift cam and requires new springs. I agree the higher the springs seat pressure over stock the more hp will be robbed but you also don't want less than stock seat pressure. I was looking at pac1218 and pac1215 springs. 1215's are just a hair less pressure than stock at full open. In another thread I asked for input on these two springs
Melting Slicks
Joined: Jun 2006
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From: Miami Florida
Ask if they are talking personal experience, do you understand how much 36 thousands is? these are the same brain doctors revving a 5,500 rpms oem cams to 7,000 with out valve float worth yet without power.
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Le Mans Master
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From: Atlanta GA
Lot of people state I will
Dave
Melting Slicks
Joined: Mar 2016
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From: Indianapolis IN
I've never seen anyone do it without springs. Might be a good reason for that but I cannot speak from experience. I really don't see why it would matter though. Plenty of guys running big lift on stock springs with stock rockers. Not something I would do personally but it does happen.
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From: Baton Rouge LA
I've never seen anyone do it without springs. Might be a good reason for that but I cannot speak from experience. I really don't see why it would matter though. Plenty of guys running big lift on stock springs with stock rockers. Not something I would do personally but it does happen.
Le Mans Master
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From: Atlanta GA
Dave
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From: Texas
Just responded in the other thread recommending the 1218s but to call PAC
I'll have to look up the 1219s. [edit] 1219 specs...
Mass (g) 67.0
Large End I.D. (in) 0.885
Large End O.D. (in) 1.207
Install Load (LB) 135.0
Install Height (in) 1.800
Open Load (LB) 348.0
Open Height (in) 1.175
Coil Bind Max 1.100
Lift Max (in) 0.625
Does anyone have the p/n of the LS3 spring and the install height on the Corvette? I'm curious what lift they're good to. Like Dave, I too have seen people espouse coil bind, yet it's not based on fact, just internet legend.Large End I.D. (in) 0.885
Large End O.D. (in) 1.207
Install Load (LB) 135.0
Install Height (in) 1.800
Open Load (LB) 348.0
Open Height (in) 1.175
Coil Bind Max 1.100
Lift Max (in) 0.625
[edit 2]
Stock LS3 cam with 1.7 rockers is .551 Intake / .520 Exhaust, so I agree the springs need to be swapped or coil bind will occur at the 1.8 install height.
Last edited by 96GS#007; Oct 31, 2016 at 10:52 PM.
Thread Starter
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Joined: Nov 2007
Posts: 65
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From: Baton Rouge LA
Just responded in the other thread recommending the 1218s but to call PAC
I'll have to look up the 1219s. [edit] 1219 specs...
Mass (g) 67.0
Large End I.D. (in) 0.885
Large End O.D. (in) 1.207
Install Load (LB) 135.0
Install Height (in) 1.800
Open Load (LB) 348.0
Open Height (in) 1.175
Coil Bind Max 1.100
Lift Max (in) 0.625
Does anyone have the p/n of the LS3 spring and the install height on the Corvette? I'm curious what lift they're good to. Like Dave, I too have seen people espouse coil bind, yet it's not based on fact, just internet legend.Large End I.D. (in) 0.885
Large End O.D. (in) 1.207
Install Load (LB) 135.0
Install Height (in) 1.800
Open Load (LB) 348.0
Open Height (in) 1.175
Coil Bind Max 1.100
Lift Max (in) 0.625
[edit 2]
Stock LS3 cam with 1.7 rockers is .551 Intake / .520 Exhaust, so I agree the springs need to be swapped or coil bind will occur at the 1.8 install height.
Thread Starter
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Joined: Nov 2007
Posts: 65
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From: Baton Rouge LA
You can just bolt them on and no need to change springs with the stock cam as you will be getting only though important .036 thousands extra lift if using the 1.8 and .054 with the 1.85s the heavier load springs will end up consuming half your gains if you went that route.
Common Misconception:
Many people mistakenly think that using higher seat pressures causes a reduction in the horsepower delivered to the flywheel because higher seat pressures (and also higher spring rates required for high performance) require horsepower to compress the springs. This thinking is simply incomplete! For every valve that is opening and its valve spring being compressed, another valve is closing and its valve spring is expanding. This expansion returns the energy to the valve train and the engine. This results in a net power loss of "0" hp. Many engineering texts refer to this as the "regenerative characteristic" of the valve train. Recent tests at Crane have shown no horsepower loss on a hydraulic roller equipped engine when changing the seat pressure from 135# to 165#. Power actually improved significantly at top end, probably due to better control of the relatively heavy valves in the engine."
better seating springs don't rob hp. The do put extra wear on components though so you need to verify rating of rockers and don't go to overboard to wear components.
Melting Slicks
Joined: Jun 2006
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From: Miami Florida
If you ask the seller guess what you need them and what alse is new, on the Trick flow ls3 heads the specs are . 650 max lift for their 460 lbs. Open pressure springs but it is also their .700 lift springs.
On the Mast ls7 heads the 430 lbs open pressure springs are good to 8,500 rpms.
If you want to know how much some one knows what he's talking about ask what he does for living.
On the Mast ls7 heads the 430 lbs open pressure springs are good to 8,500 rpms.
If you want to know how much some one knows what he's talking about ask what he does for living.
Race Director
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From: Texas
...and so what does any of this have to do with stock LS3 heads at the stock install height for the valve springs?
The OP is shooting for a quick easy 15 or so hp with minimal work that he's comfortable performing. He's not building a race engine with all sorts of custom machine work.
Another example of taking something relatively easy...math is math when calculating coil bind at a known install height and spring step...and turning it into rocket science
Le Mans Master
Joined: Oct 2014
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From: Atlanta GA
I am also and being a total newbee to this in a LS3 ( I have changed Cam , Springs and chain in older SBC and BBC motors )
Can you use the stock retainers and locks or do you need to buy retainers and locks that match the springs
If that is the case ... I might be better off buying a whole cam kit that includes springs , retainers , cam and locks
Dave
Can you use the stock retainers and locks or do you need to buy retainers and locks that match the springs
If that is the case ... I might be better off buying a whole cam kit that includes springs , retainers , cam and locks
Dave
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