LS7 Rockers - Yella Terra?
12-02-2017, 05:04 PM
#22
I have many many customers running Yella Terra products for close to a decade now and zero issues. My personal CTS-V I built in 2012.....I have 30,000 miles on that build and close to six years later zero issues and no oil consumption from the worn guides I would have had with OEM rockers and their poor geometry with higher lift cams etc. They (Yella Terra) had some teething pains with the first design in 2004 and there were a few broken rocker arms years later (this was only on the first generation cathedral head rockers).....the 2nd Gen was released shortly after and reliability was dramatically improved and then in 2012 the 3rd generation of the same rocker was released which all but eliminated any potential failures.....the 3rd generation rockers have been awesome and are still what's being currently sold today. Anything can be broken however....if your running your set-up to close to coil bind and have a missed shift you could certainly tweak a rocker as it stacks solid and something has to give.....no engine part is immune from failure but the parts offered today are going to offer you the peace of mind your looking for
Changing out a broken rocker arm (worst case scenario) is a piece of cake compared to having to remove and R&R your heads I assure you but the chance of having an issue is slim to none. Are they designed for 100K miles? No....but neither is anything else in a performance engine with a higher lift cam and a bunch more lobe intensity. You would have had to replace your valve springs three time if you were trying to build that kind of life expectancy in your performance engine....stock is stock....its meant and designed for the long haul making less power naturally along the way. A modified engine isn't meant for that type of cycle time but can approach half of that with very little fanfare besides a spring replacement midway there. You cant run a .650 lift cam and expect to get the same life out of the valve springs.....there is always a price to pay when modding your vehicle but most of us don't rack up the kind of mileage that even bring some of those longevity short comings to light (the biggest deal being valve spring replacement from time to time to avoid breaking a spring and potentially floating the valve and have it make contact with your piston).
Anyway....this response went a bit off topic but what I said about the YT stuff is spot on. I have designed 100's of combinations for my customers over the years and every single one of them are fitted with YT rockers....how many threads have you seen with a Mamo package and a customer griping about broken rocker arms?? Bad news travels fast and if it was an issue....a real issue, I assure you that you would know about it. I run them on my own personal hotrods.....is there a better endorsement than that how I feel about their function and reliability?
If there was a better product out there for the money I would be running those and recommending the same for all my clients
-Tony
__________________
www.mamomotorsports.com
Tony@MamoMotorsports.com
Anything worth doing is worth doing well. Build it right the first time....its alot cheaper than building it twice!!
www.mamomotorsports.com
Tony@MamoMotorsports.com
Anything worth doing is worth doing well. Build it right the first time....its alot cheaper than building it twice!!
Last edited by Tony @ Mamo Motorsports; 12-02-2017 at 05:11 PM.
12-02-2017, 08:40 PM
#23
ModSquad
iTrader: (6)
Hi G, thanks for the kind words.
I BELIEVE "velle" can not read !
The RACE engine starts/stops (temp-up/temp-down) NOT OFTEN in its life, constant internal temperatures. (Little Heat Treat)
The DD engine operates each day with OFTEN start/stops. (Much Heat Treat)
NOW, I do NOT "build" LS engines, I assembly LS engines.
I do BUILD (manufacturer) components.
NEXT, "Race Only" = NOT TRUE (about 20%)
Examples LS-x :
Trailer Queens = 10%
Driven each Day = 20%
Professional Racing engines = 20%
Produce Development engines = 10%
Genset/Pump engines = 15 % (25K hour life)
Toy engines = 10%
Military/other types = 15%
I worked with Carl Wegner on the NASCAR GN-West LS project.
We fit the GM rockers with CHE's, NEVER have had a problem to THIS DAY.
THUS D9, good choice.
Lance
I BELIEVE "velle" can not read !
The RACE engine starts/stops (temp-up/temp-down) NOT OFTEN in its life, constant internal temperatures. (Little Heat Treat)
The DD engine operates each day with OFTEN start/stops. (Much Heat Treat)
NOW, I do NOT "build" LS engines, I assembly LS engines.
I do BUILD (manufacturer) components.
NEXT, "Race Only" = NOT TRUE (about 20%)
Examples LS-x :
Trailer Queens = 10%
Driven each Day = 20%
Professional Racing engines = 20%
Produce Development engines = 10%
Genset/Pump engines = 15 % (25K hour life)
Toy engines = 10%
Military/other types = 15%
I worked with Carl Wegner on the NASCAR GN-West LS project.
We fit the GM rockers with CHE's, NEVER have had a problem to THIS DAY.
THUS D9, good choice.
Lance
You said that you “do not fit aluminum rockers”. So I asked if you ever build street engines, which LOTS of people use aluminum rockers with. Simple question really.
Can you post data to verify your “heat treat” theory? I’d be impressed to see what you’ve found concerning this.
12-02-2017, 09:53 PM
#24
FYI on Aluminum 2xxx, 6xxx and 7xxx series heat Treatment:
Solution Treating (softening)
Solution heat treatment is done by raising the alloy temperature to about 980 degrees F and holding it there for about an hour.
Aging (hardening)
Three commonly used time/temperature cycles are used for aging—one hour at 400 degrees F; five hours at 350 degrees F; and eight hours at 325 degrees F. All are equally effective.
As you can see, it's VERY unlikely that an aluminum component used internally in an engine would be subjected to a minimum 980°F for one CONTINUOUS hour turning it back into the softer T4 condition.
Additionally, it is VERY unlikely that a component used internally in an engine would be subjected to even 325°F-400°F for the required length of time to sufficiently strengthen the material.
The tensile strength of aluminum is not greatly effected until temperatures over 400°F are reached. I HIGHLY doubt aluminum rocker arms will ever see this temperature, and if they did, there are other parts that have long failed before the rocker would.
These are my own opinions based on the research I have done. I do not claim to be a metallurgist, but I know enough about the subject to put this on a public forum. It is however always open for debate.
Cole
Solution Treating (softening)
Solution heat treatment is done by raising the alloy temperature to about 980 degrees F and holding it there for about an hour.
Aging (hardening)
Three commonly used time/temperature cycles are used for aging—one hour at 400 degrees F; five hours at 350 degrees F; and eight hours at 325 degrees F. All are equally effective.
As you can see, it's VERY unlikely that an aluminum component used internally in an engine would be subjected to a minimum 980°F for one CONTINUOUS hour turning it back into the softer T4 condition.
Additionally, it is VERY unlikely that a component used internally in an engine would be subjected to even 325°F-400°F for the required length of time to sufficiently strengthen the material.
The tensile strength of aluminum is not greatly effected until temperatures over 400°F are reached. I HIGHLY doubt aluminum rocker arms will ever see this temperature, and if they did, there are other parts that have long failed before the rocker would.
These are my own opinions based on the research I have done. I do not claim to be a metallurgist, but I know enough about the subject to put this on a public forum. It is however always open for debate.
Cole
12-02-2017, 10:04 PM
#25
TECH Senior Member
Thru reading all this I have come to a conclusion that it's not heat that affects aluminum rockers. It's work-hardening. Even though not visible, there is some amount of flexing in every aluminum rocker, which over time (granted,a LONG time) causes them to be work-hardened. And as they become more work-hardened, they become more brittle, leading to eventual breakage. Just a theory...
Not sure every alloy is equally affected, but it has to be a factor.
Not sure every alloy is equally affected, but it has to be a factor.
12-03-2017, 09:37 AM
#26
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There are no issues running the Yella Terra rockers....OEM rockers will decrease the service life of your cylinder heads dramatically prematurely wearing out your valve guides from the side loading and scrubbing across the top of the valve. They are completely out of their element in a performance LS7 build that includes aftermarket cams with more lobe lift and intensity and twice the OEM spring pressure. Your valve guides will be toast in 10-15K miles forcing you to replace all of them and re-valvejob the head as well which is a huge (expensive) endeavor. Once the wear gets bad you will consume oil and performance will suffer due to the valves not sealing properly when there is to much slop in the guide bore housing from the hour glassed shape the OEM rocker will eventually create.
I have many many customers running Yella Terra products for close to a decade now and zero issues. My personal CTS-V I built in 2012.....I have 30,000 miles on that build and close to six years later zero issues and no oil consumption from the worn guides I would have had with OEM rockers and their poor geometry with higher lift cams etc. They (Yella Terra) had some teething pains with the first design in 2004 and there were a few broken rocker arms years later (this was only on the first generation cathedral head rockers).....the 2nd Gen was released shortly after and reliability was dramatically improved and then in 2012 the 3rd generation of the same rocker was released which all but eliminated any potential failures.....the 3rd generation rockers have been awesome and are still what's being currently sold today. Anything can be broken however....if your running your set-up to close to coil bind and have a missed shift you could certainly tweak a rocker as it stacks solid and something has to give.....no engine part is immune from failure but the parts offered today are going to offer you the peace of mind your looking for
Changing out a broken rocker arm (worst case scenario) is a piece of cake compared to having to remove and R&R your heads I assure you but the chance of having an issue is slim to none. Are they designed for 100K miles? No....but neither is anything else in a performance engine with a higher lift cam and a bunch more lobe intensity. You would have had to replace your valve springs three time if you were trying to build that kind of life expectancy in your performance engine....stock is stock....its meant and designed for the long haul making less power naturally along the way. A modified engine isn't meant for that type of cycle time but can approach half of that with very little fanfare besides a spring replacement midway there. You cant run a .650 lift cam and expect to get the same life out of the valve springs.....there is always a price to pay when modding your vehicle but most of us don't rack up the kind of mileage that even bring some of those longevity short comings to light (the biggest deal being valve spring replacement from time to time to avoid breaking a spring and potentially floating the valve and have it make contact with your piston).
Anyway....this response went a bit off topic but what I said about the YT stuff is spot on. I have designed 100's of combinations for my customers over the years and every single one of them are fitted with YT rockers....how many threads have you seen with a Mamo package and a customer griping about broken rocker arms?? Bad news travels fast and if it was an issue....a real issue, I assure you that you would know about it. I run them on my own personal hotrods.....is there a better endorsement than that how I feel about their function and reliability?
If there was a better product out there for the money I would be running those and recommending the same for all my clients
-Tony
I have many many customers running Yella Terra products for close to a decade now and zero issues. My personal CTS-V I built in 2012.....I have 30,000 miles on that build and close to six years later zero issues and no oil consumption from the worn guides I would have had with OEM rockers and their poor geometry with higher lift cams etc. They (Yella Terra) had some teething pains with the first design in 2004 and there were a few broken rocker arms years later (this was only on the first generation cathedral head rockers).....the 2nd Gen was released shortly after and reliability was dramatically improved and then in 2012 the 3rd generation of the same rocker was released which all but eliminated any potential failures.....the 3rd generation rockers have been awesome and are still what's being currently sold today. Anything can be broken however....if your running your set-up to close to coil bind and have a missed shift you could certainly tweak a rocker as it stacks solid and something has to give.....no engine part is immune from failure but the parts offered today are going to offer you the peace of mind your looking for
Changing out a broken rocker arm (worst case scenario) is a piece of cake compared to having to remove and R&R your heads I assure you but the chance of having an issue is slim to none. Are they designed for 100K miles? No....but neither is anything else in a performance engine with a higher lift cam and a bunch more lobe intensity. You would have had to replace your valve springs three time if you were trying to build that kind of life expectancy in your performance engine....stock is stock....its meant and designed for the long haul making less power naturally along the way. A modified engine isn't meant for that type of cycle time but can approach half of that with very little fanfare besides a spring replacement midway there. You cant run a .650 lift cam and expect to get the same life out of the valve springs.....there is always a price to pay when modding your vehicle but most of us don't rack up the kind of mileage that even bring some of those longevity short comings to light (the biggest deal being valve spring replacement from time to time to avoid breaking a spring and potentially floating the valve and have it make contact with your piston).
Anyway....this response went a bit off topic but what I said about the YT stuff is spot on. I have designed 100's of combinations for my customers over the years and every single one of them are fitted with YT rockers....how many threads have you seen with a Mamo package and a customer griping about broken rocker arms?? Bad news travels fast and if it was an issue....a real issue, I assure you that you would know about it. I run them on my own personal hotrods.....is there a better endorsement than that how I feel about their function and reliability?
If there was a better product out there for the money I would be running those and recommending the same for all my clients
-Tony
I will run the Yella-Terra rockers. My CHE decision was mainly based on reading a bunch of poor reviews of the Yella-Terra. After reading this I've gone back to them and they are all from <2010. It looks like they have iterated on the design quite a bit. I really like the roller tip design and the price tag.
FYI on Aluminum 2xxx, 6xxx and 7xxx series heat Treatment:
Solution Treating (softening)
Solution heat treatment is done by raising the alloy temperature to about 980 degrees F and holding it there for about an hour.
Aging (hardening)
Three commonly used time/temperature cycles are used for aging—one hour at 400 degrees F; five hours at 350 degrees F; and eight hours at 325 degrees F. All are equally effective.
As you can see, it's VERY unlikely that an aluminum component used internally in an engine would be subjected to a minimum 980°F for one CONTINUOUS hour turning it back into the softer T4 condition.
Additionally, it is VERY unlikely that a component used internally in an engine would be subjected to even 325°F-400°F for the required length of time to sufficiently strengthen the material.
The tensile strength of aluminum is not greatly effected until temperatures over 400°F are reached. I HIGHLY doubt aluminum rocker arms will ever see this temperature, and if they did, there are other parts that have long failed before the rocker would.
These are my own opinions based on the research I have done. I do not claim to be a metallurgist, but I know enough about the subject to put this on a public forum. It is however always open for debate.
Cole
Solution Treating (softening)
Solution heat treatment is done by raising the alloy temperature to about 980 degrees F and holding it there for about an hour.
Aging (hardening)
Three commonly used time/temperature cycles are used for aging—one hour at 400 degrees F; five hours at 350 degrees F; and eight hours at 325 degrees F. All are equally effective.
As you can see, it's VERY unlikely that an aluminum component used internally in an engine would be subjected to a minimum 980°F for one CONTINUOUS hour turning it back into the softer T4 condition.
Additionally, it is VERY unlikely that a component used internally in an engine would be subjected to even 325°F-400°F for the required length of time to sufficiently strengthen the material.
The tensile strength of aluminum is not greatly effected until temperatures over 400°F are reached. I HIGHLY doubt aluminum rocker arms will ever see this temperature, and if they did, there are other parts that have long failed before the rocker would.
These are my own opinions based on the research I have done. I do not claim to be a metallurgist, but I know enough about the subject to put this on a public forum. It is however always open for debate.
Cole
---------------------------------------------------------------
Thank you all for the feedback. The first-hand responses are excellent and make this forum such a powerful tool.
I look forward to contributing with my build and results, soon.
Kind regards,
D
12-03-2017, 11:18 AM
#27
FormerVendor
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Alum-A-Therm = Westminster, CA. Hi Cole, yes a good tech report in a "kind" way, not as others have done who state MY BUSINESS.
I was employed at Alum-A-Therm in Westminster, CA. (1970)
We ran a LOT of Boeing 7075 air frame forgings.
I also operated the Annealing Ovens, not dressed in your tech.
I give "G" A high grade for his report of Work Heat, yes this is the cause of the higher temperatures seen.
Observe the Valve Spring, just a piece of steel rod AND when bent (by hand) it becomes HOT.
YES I have turned Valve Springs Blue during engine dyno testing, then added Oil Jets used to cool springs.
THUS the term "heat treat" should include Work Hardening "G's" tech.
Now Empirical Data : Tom Gloy Trans-AM racing.
The engine rebuild, after each race, saw the Al rocker arms and pistons in the trash can with no visible damage.
A report from Yellow Tera about their rocker arm Alloy & Heat Treat could ADD to the tech in this thread ?
I have found the use of Lash Caps, a better form of Valve Adjustment.
Lance
I was employed at Alum-A-Therm in Westminster, CA. (1970)
We ran a LOT of Boeing 7075 air frame forgings.
I also operated the Annealing Ovens, not dressed in your tech.
I give "G" A high grade for his report of Work Heat, yes this is the cause of the higher temperatures seen.
Observe the Valve Spring, just a piece of steel rod AND when bent (by hand) it becomes HOT.
YES I have turned Valve Springs Blue during engine dyno testing, then added Oil Jets used to cool springs.
THUS the term "heat treat" should include Work Hardening "G's" tech.
Now Empirical Data : Tom Gloy Trans-AM racing.
The engine rebuild, after each race, saw the Al rocker arms and pistons in the trash can with no visible damage.
A report from Yellow Tera about their rocker arm Alloy & Heat Treat could ADD to the tech in this thread ?
I have found the use of Lash Caps, a better form of Valve Adjustment.
Lance
12-04-2017, 12:03 AM
#29
Hi Cole, yes a good tech report in a "kind" way, not as others have done who state MY BUSINESS.
I was employed at Alum-A-Therm in Westminster, CA. (1970)
We ran a LOT of Boeing 7075 air frame forgings.
I also operated the Annealing Ovens, not dressed in your tech.
I give "G" A high grade for his report of Work Heat, yes this is the cause of the higher temperatures seen.
Observe the Valve Spring, just a piece of steel rod AND when bent (by hand) it becomes HOT.
YES I have turned Valve Springs Blue during engine dyno testing, then added Oil Jets used to cool springs.
THUS the term "heat treat" should include Work Hardening "G's" tech.
Now Empirical Data : Tom Gloy Trans-AM racing.
The engine rebuild, after each race, saw the Al rocker arms and pistons in the trash can with no visible damage.
A report from Yellow Tera about their rocker arm Alloy & Heat Treat could ADD to the tech in this thread ?
I have found the use of Lash Caps, a better form of Valve Adjustment.
Lance
I was employed at Alum-A-Therm in Westminster, CA. (1970)
We ran a LOT of Boeing 7075 air frame forgings.
I also operated the Annealing Ovens, not dressed in your tech.
I give "G" A high grade for his report of Work Heat, yes this is the cause of the higher temperatures seen.
Observe the Valve Spring, just a piece of steel rod AND when bent (by hand) it becomes HOT.
YES I have turned Valve Springs Blue during engine dyno testing, then added Oil Jets used to cool springs.
THUS the term "heat treat" should include Work Hardening "G's" tech.
Now Empirical Data : Tom Gloy Trans-AM racing.
The engine rebuild, after each race, saw the Al rocker arms and pistons in the trash can with no visible damage.
A report from Yellow Tera about their rocker arm Alloy & Heat Treat could ADD to the tech in this thread ?
I have found the use of Lash Caps, a better form of Valve Adjustment.
Lance
Please explain why an aluminum connecting rod is used in THE most powerful internal combustion engine, the Top Fuel Hemi V8?
There are numerous other types of engine builds that use similar aluminum connecting rods, many of which are close to or over 3HP per cubic inch. These are HIGHLY stressed engines.
The rods or rocker arms aren't replaced because of heat cycles or work hardening, they are replaced because aluminum has a cyclic fatigue life regardless of temperature cycles.
I believe the same replacement reasoning holds true for ANY fatigue related aluminum engine component, with the exception of wear.
The component temperatures in a properly designed and cooled internal combustion engine will not reach a level where HEAT would cause a reduction in service life.
I'm just trying to shed light on the MYTH that aluminum rocker arms are a bad choice.
Case in point. The Jesel aluminum shaft rocker arms on my 406 SBC started life (in 1998) on a 358" Busch Grand National car that was built by Petty Enterprises and ran part time for a whole season (8,000+ racing miles). They have been on my car since 2004 and for 300+ passes shifting at 8100 RPM and crossing the finish line at 8400 RPM. This is withvalve springs that are 300 lbs closed and 750 lbs open. Just this year I broke down and replaced the shaft bearings in the rockers because I felt bad.
For the OP, I would not hesitate to recommend a quality aluminum rocker arm for his application. I don't have personal experience with the Yella Terra brand, so i can not add any input, but I can say I wouldn't NOT choose them because they are aluminum.
Cole
12-04-2017, 12:27 AM
#30
TECH Senior Member
Aluminum rods are used in Top Fuel engines NOT for longevity, but all-out power generation. They are changed VERY often! You do not see them used in street apps because they do not live long. The heat-cycle, work hardening thing AGAIN...
You cite cyclic fatigue life in the case of con-rods. The same applies to rocker arms, though instead of compression/extension forces contributing to short fatigue life, it's bending forces in acting as a fulcrum for valve actuation. It's these compression/extension and bending forces that cause work-hardening of aluminum, which does not require much heat to happen. Heat-treating involves various levels of heat to change metallurgical characteristics. Work-hardening involves cyclic flexing of the part involved, to its eventual failure.
You cite cyclic fatigue life in the case of con-rods. The same applies to rocker arms, though instead of compression/extension forces contributing to short fatigue life, it's bending forces in acting as a fulcrum for valve actuation. It's these compression/extension and bending forces that cause work-hardening of aluminum, which does not require much heat to happen. Heat-treating involves various levels of heat to change metallurgical characteristics. Work-hardening involves cyclic flexing of the part involved, to its eventual failure.
Last edited by G Atsma; 12-04-2017 at 12:41 AM.
12-04-2017, 01:42 AM
#31
Aluminum rods are used in Top Fuel engines NOT for longevity, but all-out power generation. They are changed VERY often! You do not see them used in street apps because they do not live long. The heat-cycle, work hardening thing AGAIN...
You cite cyclic fatigue life in the case of con-rods. The same applies to rocker arms, though instead of compression/extension forces contributing to short fatigue life, it's bending forces in acting as a fulcrum for valve actuation. It's these compression/extension and bending forces that cause work-hardening of aluminum, which does not require much heat to happen. Heat-treating involves various levels of heat to change metallurgical characteristics. Work-hardening involves cyclic flexing of the part involved, to its eventual failure.
You cite cyclic fatigue life in the case of con-rods. The same applies to rocker arms, though instead of compression/extension forces contributing to short fatigue life, it's bending forces in acting as a fulcrum for valve actuation. It's these compression/extension and bending forces that cause work-hardening of aluminum, which does not require much heat to happen. Heat-treating involves various levels of heat to change metallurgical characteristics. Work-hardening involves cyclic flexing of the part involved, to its eventual failure.
If the rocker arm or connecting rod is being work hardened and fails, then it has not been properly designed or used for that application.
Do you think Jesel would still be in business if aluminum was such a poor choice of materials for rocker arms?
Just for clarification, the connecting rod in a Top Fuel engine does not generate power, it transfers it to the crankshaft. They don't last very long because they are highly stressed and are "cheap" insurance compared to the cost of a block, heads, etc. or losing a round of competition should one fail. Again, nothing to do with heat cycles at all and purely mechanical fatigue.
Cole
Last edited by ColeGTO; 12-04-2017 at 01:47 AM.
12-04-2017, 11:17 AM
#32
TECH Senior Member
Mechanical fatigue/cyclic fatigue; synonymous. I maintain that is happening with aluminum rockers, possibly due to poor design or metallurgy. Obviously Jesel is doing something right. Ever notice when you repeatedly bend a piece of metal (especially aluminum)until the breaking point that it is quite warm at the fracture point? And you say heat has nothing to do with it??
12-22-2017, 06:09 AM
#33
Holy crap. What a bunch of BS in this thread.
Pantera, you ought to tone it down. It appears you didn't pick up enough metallurgical expertise in all of your "experience" to be debating this topic.
ColeGTO explained it very well. Everybody else is just throwing buzzwords around.
Pantera, you ought to tone it down. It appears you didn't pick up enough metallurgical expertise in all of your "experience" to be debating this topic.
ColeGTO explained it very well. Everybody else is just throwing buzzwords around.
12-22-2017, 05:59 PM
#34
TECH Addict
iTrader: (1)
I agree with you to a point. As a (retired)Tool & Diemaker, I had some metallurgy classes as an apprentice, AND 4O+ years experience in the metal trades. I can assure you that heat CAN, and DOES cause work hardening, depending on what material we are talking about. Most steel loses its "temper" at temperatures at or above 400 degrees. I sincerely doubt aluminum rockers are subjected to enough heat to be work hardened. But they do fail after enough cycles, with absolutely no advance warning. Bottom line is, aluminum is a poor choice for longevity-in any application-Remember the Vega engine?? Also, O.E.M. aluminum rollers HAVE been installed as original equipment before: Crane Gold aluminum rollers were installed O.E.M. on the original LT4 1996 C4 Corvette motors. BUT-We are talking .400-.430 lift here, maybe 125lbs. seat pressure and Maybe 250-300lbs open. I don't profess to know the exact spring #s, but I think this is close. My point being the cam/heads LS motors see a LOT more spring pressure and much faster ramp rates. That said, many times the roller tip wheel does not spin due to insufficient bearing area under extreme spring pressure. Which is exactly when you do need it. In my opinion, the old saying "nothing succeeds like success" applies here. If Tony M. has been running them for years without issues, I would not hesitate to run them myself. However, they may, or may NOT, be the answer to the worn valveguides we are seeing.. I digress
12-22-2017, 06:58 PM
#36
TECH Addict
iTrader: (1)
I'm also curious about this: Does anyone-YT or whoever-Make an affordable 1.7:1 OFFSET intake roller rocker, or any rocker, for the LS7? Years ago, when the LS7 debuted in '06, I was talking with Kurt Urban and Billy Briggs when they were both at Wheel to Wheel. I have great respect for BOTH of them as Engine Bulders. They both recommended not running 1.8:1 rockers on the street (at that time) because they are harder on valvesprings. Then Kurt said " But then G.M. goes and installs them as O.E.M. equipment on the LS7 now, so go figure.....
12-23-2017, 12:02 AM
#37
Having said that, the valvetrain is a SYSTEM and needs to be designed as such. A valvespring spec'd for a lobe and running a 1.6, 1.6 or 1.7 is different than running a 1.8. When you're pushing the limits of the system, the Spintron is your friend.
Cole
Last edited by ColeGTO; 12-23-2017 at 12:35 AM.
12-23-2017, 12:34 AM
#38
Cole
12-23-2017, 07:54 AM
#40
TECH Enthusiast
I am wondering on the shaft mounted rockers the shaft provides additional side support that the single stand ones (factory) can not do as well. Even I think the Yella Terra ones have a dual rocker per unit set up which I think probably helps out a lot. In fact on some of these rebuild kits I wish they used a 5 inch shaft instead of whatever it is a 2 inch shaft so when you rebuilt them they now become a dual rocker unit. Maybe at 325 pounds of open spring pressure not an issue but when you get over 400 pounds it might help.