Rockers for LS1?

[Vettezuki]

There's an outside chance the Gods will stop kicking me in the teeth in the coming moths, at least enough to play maybe a tiny bit with the Vette. If I have to pull the engine to investigate and fix the cam knock, might do some other things that I've wanted to do at the same time, namely rockers and lifters. Morel link bar lifters seem the way to go for high value, but what about Rockers? I think I want to keep the stock ratio unless changing will give better higher rev performance without risking passing smog.

[94cobra69ss396]

What are the specs on your cam again? I don't know anything about the LS1 but upping the rocker ratio will give you more lift and a faster opening/closing rate. It could make more power if the heads flow enough to use it but it may also hurt power and RPM potential if the spring rate can't handle it. I've only looked your car over once and I can tell you that your biggest issue right now is your tiny exhaust. You need to address that first.

[Vettezuki]

Cam is 224/224 114LSA .566 lift.

These are just things (at least lifters) I would probably do while the engine is out having the cam knock issue resolved. The rockers could wait.

[94cobra69ss396]

I don't know how good the stock LS lifters are but I have almost 200,000 miles on the stock roller rockers in my '99 Suburban which has the 5.7 Vortec (R motor). Granted they don't see the lift and RPM yours do but still.

For the rockers, if you went from the stock 1.7 to a 1.8 you'd see an increase of .033 for a lift of .599. Do you have the piston-to-valve clearance for that? How about the springs, will that put them coil bind?

[Vettezuki]

I don't know how good the stock LS lifters are but I have almost 200,000 miles on the stock roller rockers in my '99 Suburban which has the 5.7 Vortec (R motor). Granted they don't see the lift and RPM yours do but still.

For the rockers, if you went from the stock 1.7 to a 1.8 you'd see an increase of .033 for a lift of .599. Do you have the piston-to-valve clearance for that? How about the springs, will that put them coil bind?

They're not stock springs, but I don't remember what their spring tension is. We would have to measure all these things. Come to think of it, I could also swap the valves. I have a set of the titanium valves. The heads are heavily ported 4.8L truck heads. (Common back in the late 90s early 2000s as a poor man's solution to a little more compression and flow.)

[Shaolin Crane]

Your springs are 165-185# installed and started to bind around.620 IIRC. However the only rockers I would run on an LS are the chromoly magnums and those only come in a stock lift. The valves you have are fine and iI would stick with those, if anything, have some bowl work done to lower your compression.

[C5Natie]

Its been proven the best rockers for LS motors are stockers with upgraded bearings and trunions. Theyre light, strong and handle high rpm. Theres been failures with just about every aftermarket brand of rockers. If you do a search I think youll find a lot of good info. The upgrade trunion kit from Comp Cams is cheap insurance. I made a video on this a while ago.

http://www.compcams.com/WhatsNew/Files/compls1rockertrunionupgrade.pdf

https://www.youtube.com/watch?v=0IoaGBTq2fE

[Vettezuki]

Thanks Nate. What do you think about lifters?

[enkeivette]

Go as big as you can on the lift. I don't think it will have a dramatic effect on smog unlike a change in duration. And any change in duration will be negligible. So its not really pushing more air into the cylinder, just allowing more efficient operation at high rpm. (Stand by for correction.)

Fab up some headers while you're at it. You have 2 hands, a welder, and no excuse. Just jump in balls first, thats the way to do these things.

[enkeivette]

If I were you Id buy some cheap 1 3/4 headers for a regular SB C3, then get some LS flanges, and cut, tweak, and tack to modify.

[Vettezuki]

My cup runneth over. I'll have Jammer fab ups some headers after some of the other bits are done. Then retune and probably stop there as far as the engine is concerned. I should be at around 430WHP NA through a Roman era IRS and still passing smog. That's about as good as its gonna get NA without major changes, and 430 @ 3,100lbs full wet ain't too shaby. Shedding another 100 lbs shouldn't be too hard either.

[C5Natie]

Thanks Nate. What do you think about lifters?

I use stock LS7 lifters. Actually the LS7's have become the oem replacement for all LS motors. Ive had no issues with them even when I was spinning my old LS6 passed 7000rpm. Any times the heads come off I'll replace the lifter trays tho. At like $8ea theyre cheap insurance. Ive heard complaints about people with the Rhodes or Morel link bar lifters. Theyre usually noisy and bleed down too much, at least on street cars.

[Vettezuki]

I use stock LS7 lifters. Actually the LS7's have become the oem replacement for all LS motors. Ive had no issues with them even when I was spinning my old LS6 passed 7000rpm. Any times the heads come off I'll replace the lifter trays tho. At like $8ea theyre cheap insurance. Ive heard complaints about people with the Rhodes or Morel link bar lifters. Theyre usually noisy and bleed down too much, at least on street cars.

I know people were using the Caddy racing lifters for a while. Wonder if there's any difference there. I certainly like the price tag on these upgrades!

[Shaolin Crane]

Its been proven the best rockers for LS motors are stockers with upgraded bearings and trunions. Theyre light, strong and handle high rpm. Theres been failures with just about every aftermarket brand of rockers. If you do a search I think youll find a lot of good info. The upgrade trunion kit from Comp Cams is cheap insurance. I made a video on this a while ago.

http://www.compcams.com/WhatsNew/Files/compls1rockertrunionupgrade.pdf

https://www.youtube.com/watch?v=0IoaGBTq2fE

Best? Hardly. Viable option, absolutely. The stockers will flex before they break, but if you're breaking rockers there is ALWAYS a reason for it. Regardless if stock or not.

[Shaolin Crane]

Go as big as you can on the lift. I don't think it will have a dramatic effect on smog unlike a change in duration. And any change in duration will be negligible. So its not really pushing more air into the cylinder, just allowing more efficient operation at high rpm. (Stand by for correction.)

Fab up some headers while you're at it. You have 2 hands, a welder, and no excuse. Just jump in balls first, thats the way to do these things.

Yup, only downside to high lift and low duration is the ramp rates kill the valve springs pretty quickly. Best bet would be to shim his current springs to 200lbs

[C5Natie]

Best? Hardly. Viable option, absolutely. The stockers will flex before they break, but if you're breaking rockers there is ALWAYS a reason for it. Regardless if stock or not.

Just going off what I've seen and experienced. Stockers break at the fulcrum bearing so the upgrade fixes that. The problem with the aftermarket ones is that the design of the valvetrain doesn't allow for enough material where the arm extends over to the pushrod and they break there. That's why I always say to do a search and check out the forums. There's tons oof info on the matter, so it's not just one persons opinion. You'll find that stockers with upgraded bearings have been the most ssuccessful with the most benefits. There are no lighter ones then stock available iirc.

[Shaolin Crane]

Just going off what I've seen and experienced. Stockers break at the fulcrum bearing so the upgrade fixes that. The problem with the aftermarket ones is that the design of the valvetrain doesn't allow for enough material where the arm extends over to the pushrod and they break there. That's why I always say to do a search and check out the forums. There's tons oof info on the matter, so it's not just one persons opinion. You'll find that stockers with upgraded bearings have been the most ssuccessful with the most benefits. There are no lighter ones then stock available iirc.

Like I said, there is always a reason for a rocker breaking, usally improper coil bind and pushrod length, like i said, the stockers will flex, if the rocker doesn't bbreak, the stud or the pushrod will, too many variables to give the title "the best". If you want the absolute best nothing beats a shaft mount setup, but the cost is up there. I'd personally run the magnums, everyone is entitled to their own opinion.

[C5Natie]

Yeah youre not gonna beat a Jesel shaft mount setup but it cost a very pretty penny. I was referring to oem style.

[Vettezuki]

. . . However the only rockers I would run on an LS are the chromoly magnums and those only come in a stock lift. . . .

Link? Not sure what I'm looking at.

This is an NA street car. My cam is moderate and I won't/can't go bigger. I just want a linear power curve to 430~WHP and dead reliable.

I'M at 390~ with stock valvetrain and exhaust manifolds through cats. My idea with the lifters and rockers is simply to spin more readily to peak power. I'm not sure going higher rpm with my 224/224 114LSA .566 lift is going to bring a lot to the party. I have redline set at 6,500 RPM.

Exhaust is where the bulk of "easy" power is sitting on the table. However, the engine has to come out to deal with the cam knock, so . . gulp. . . while I'm at it . . .