roller rockers
07-29-2013, 10:13 PM
#2
Roller tip rockers are often needed to reduce/diminish premature valveguide
wear in aftermarket cylinder heads which use bronze valve guides. It's be-
lieved that the less friction is worth a few ponies however since they're made
of aluminum they tend to be bulky and heavy and contribute to early valve-
float if the proper valvesprings are not used. The GM rocker arm is about the
best option with a trunion upgrade kit from Comp Cams or Lunati.....research
is your friend on this site.
wear in aftermarket cylinder heads which use bronze valve guides. It's be-
lieved that the less friction is worth a few ponies however since they're made
of aluminum they tend to be bulky and heavy and contribute to early valve-
float if the proper valvesprings are not used. The GM rocker arm is about the
best option with a trunion upgrade kit from Comp Cams or Lunati.....research
is your friend on this site.
07-30-2013, 07:02 AM
#4
Yep screw roller rockers...I wouldn't run them, even to the point when I buy some trick flow heads I'm going to have the bronze valve guides replaced so I don't have to run rollers, some have them and love them, but to me there is a reason GM didn't design the LS engine using them...but do a search and you will get plenty of info
07-30-2013, 03:38 PM
#5
I'd love to run Roller Rockers. I had this debate in my build thread some time ago and usually pop up in a YT thread to shake my head.
The stock rockers are great pieces. Very light and very strong. If you run PM guides, you should be fine with the stock rockers and decent spring pressure (130-160 closed/380-450 open). As you get into higher valve lifts (.630"+) and stronger springs, the stock rockers really start to become less ideal and starts to side load the valves and wear parts pretty bad with their "rocking chair" motion of scrubbing across the valve tip.
The problem is a good roller rocker alternative doesn't exist at a good price point. The Yella Terra is probably the best option. It's doesn't cost a fortune, doesn't add an insane amount of weight, and cleans up the wipe and valve scrubbing issues. The issue with them has been it does add some weight so you need more spring pressure, and because it is aluminum, they fatigue and break. Several revisions later and maybe they have it.
The best option would be like Comp's SBC steel roller rockers. They make something like that for the LS1 but it's a 1.8:1 ratio rocker. Give us a good, strong, lightweight steel roller rocker for under $500 and a lot of folks would run it.
The stock rockers are great pieces. Very light and very strong. If you run PM guides, you should be fine with the stock rockers and decent spring pressure (130-160 closed/380-450 open). As you get into higher valve lifts (.630"+) and stronger springs, the stock rockers really start to become less ideal and starts to side load the valves and wear parts pretty bad with their "rocking chair" motion of scrubbing across the valve tip.
The problem is a good roller rocker alternative doesn't exist at a good price point. The Yella Terra is probably the best option. It's doesn't cost a fortune, doesn't add an insane amount of weight, and cleans up the wipe and valve scrubbing issues. The issue with them has been it does add some weight so you need more spring pressure, and because it is aluminum, they fatigue and break. Several revisions later and maybe they have it.
The best option would be like Comp's SBC steel roller rockers. They make something like that for the LS1 but it's a 1.8:1 ratio rocker. Give us a good, strong, lightweight steel roller rocker for under $500 and a lot of folks would run it.
07-30-2013, 06:00 PM
#6
Yep screw roller rockers...I wouldn't run them, even to the point when I buy some trick flow heads I'm going to have the bronze valve guides replaced so I don't have to run rollers, some have them and love them, but to me there is a reason GM didn't design the LS engine using them...but do a search and you will get plenty of info
Last edited by ckpitt55; 07-30-2013 at 06:06 PM.
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07-30-2013, 07:02 PM
#8
Teching In
This is an interesting thread for me. I just bought my 1st engine (without a car around it) for my 1st build and this is something I was curious about. Garcr4 makes a pretty powerful arguement. To be honest my opinion isn't worth much at my experience level but I think nascar would run what's best. Let me ask this: why did the LT1 vettes (or was it only LT4s) have rollers and not the f-bodies if they're not better? Just to help justify the cost difference between the cars? Does it make a difference on the LT engines vs the LS. Just throwing it out there.
07-30-2013, 08:31 PM
#9
Cost is why GM did it. And it's another moving piece that can fail with a roller tip.
Btw, any race motor designed around the stock motor has two things working for it that you don't with your stock motor: lightweight valvetrain and spintron testing.
They choose their lobes very carefully and test the system on the spintron. They adjust pushrod strength, lighten the valves, play with spring pressures, and work within the design parameters of the lifters so they don't get failure. The lobe design is really the most important as the crashing of the exhaust lobe opening is what destroys valvetrains. The lifter is launched off the nose of the cam lobe, lofts, and crashes back down, breaking lifters, cams, and rockers. Flex in the pushrods can do the same thing.
Btw, any race motor designed around the stock motor has two things working for it that you don't with your stock motor: lightweight valvetrain and spintron testing.
They choose their lobes very carefully and test the system on the spintron. They adjust pushrod strength, lighten the valves, play with spring pressures, and work within the design parameters of the lifters so they don't get failure. The lobe design is really the most important as the crashing of the exhaust lobe opening is what destroys valvetrains. The lifter is launched off the nose of the cam lobe, lofts, and crashes back down, breaking lifters, cams, and rockers. Flex in the pushrods can do the same thing.
07-30-2013, 11:43 PM
#11
On The Tree
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thanks guys for the info it is greatly appreciated i will do a lot more research im trying to learn everything i can about these motors, i was a diesel mechanic and built a sled puller then turned it into a drag truck, i now sold it and bought my Camaro and going to build a street/strip car out of it. i want to do all of the work myself.
07-31-2013, 09:28 AM
#13
If they were prone to fail, they would not use them at all. Also, it ain't Cup, where a new motor goes in every race. They were also used in Grand Am in what is now the Continental Series. After trying other options the Spirit of Daytona team settled on the trunion upgrade for their Pontiac GTO's.
We are using the comp upgrade in our road race Corvette and in the first seven weekends there has not been a hint of a problem with them.
Prior to that a stock rocker failed almost immediately.
We are using the comp upgrade in our road race Corvette and in the first seven weekends there has not been a hint of a problem with them.
Prior to that a stock rocker failed almost immediately.
07-31-2013, 09:41 AM
#14
I really wish someone would A/B stock rockers vs. rollers on a spintron and end this whole pissing match once and for all.
The bottom line is that there are tradeoffs to both, and individual part selection isn't nearly as important as thorough component matching and attention to detail on setup / install. It's not just about the rocker - it's the right lobes, the right lifters, spring pressure, pushrod length and stiffness, rocker ratio, wipe pattern, etc.
The bottom line is that there are tradeoffs to both, and individual part selection isn't nearly as important as thorough component matching and attention to detail on setup / install. It's not just about the rocker - it's the right lobes, the right lifters, spring pressure, pushrod length and stiffness, rocker ratio, wipe pattern, etc.
Last edited by ckpitt55; 07-31-2013 at 09:52 AM.
07-31-2013, 10:07 AM
#15
TECH Senior Member
The issue most of the time is improper matching of valve-train. People have the tendency to do things on the big side, simply because they do not understand enough to make good decisions matching components.
The criteria is almost always the same:
1- I want the most power
2- I want it cheap
Other contributing factors are like improper install procedures and blueprinting of tolerances.
The criteria is almost always the same:
1- I want the most power
2- I want it cheap
Other contributing factors are like improper install procedures and blueprinting of tolerances.
07-31-2013, 10:58 AM
#16
07-31-2013, 12:37 PM
#18
guys that only care about dyno numbers are missing the point. the real benefit is the ability to optimize your valvetrain geometry, which becomes much more important if you don't want to wear out the valve guides on aftermarket heads in 10k miles.
if you have any more details you could share on setup / results I'd be very interested to see it if you're willing to share. what engine speeds are we talking here?
Last edited by ckpitt55; 07-31-2013 at 12:50 PM.
07-31-2013, 01:01 PM
#19
That is about as much info as I can give. Someone bought the info and can't give anything else out.
Stock rockers are the way to go. If you want to put rollers in, get better lifters and a dual spring with 180+ on the seat and 450+ open regardless of lift.
Was working with a guy, stock ls6 cam with 1.8 roller rockers, couldn't keep valve train under control up to 6500 rpm with 190 on the seat and 480 open!!! So anyone who tells me stock sucks, I just laugh at them.
Stock rockers are the way to go. If you want to put rollers in, get better lifters and a dual spring with 180+ on the seat and 450+ open regardless of lift.
Was working with a guy, stock ls6 cam with 1.8 roller rockers, couldn't keep valve train under control up to 6500 rpm with 190 on the seat and 480 open!!! So anyone who tells me stock sucks, I just laugh at them.