BROKEN ROCKER ARMS AT 6900 RPM LAUNCH ON 2 STEP! ANY IDEAS?????

[SILVIADRIFTR]

Problem: At high rpm launches off the 2 step(6900-7200), I have broken 3 rocker arms so far and shot out 1 lash cap. It is almost like the rocker arm is coming off the lifter, binding, and breaking.

Head setup: Ferrea valves, retainers, dual springs, lockers, lockers, and locators. HKS 272 step 2 cams. Tomei rocker arm stoppers. Arp head bolts. Factory lash caps and lifters.

I have been looking into doing the Lash killer set from HKS but have been receiving conflicting info as to whether I can run them with the 272 step 2's or if they can only be run with the step 3's. But I don't know if this will solve my problems.

If anyone has run into this problem I would greatly appreciate the help.

[Fireplug]

I have the exact same setup in my head as you do...everything is the same. This may not be of much help, but it's what I understand.

#1. From what I've heard, the lash killer kit is trash...The people that have told me this haven't gone into detail about why it is...but they are very reputable SR guys so I trust them. Also, I have heard the same thing about the lash killer kit not working with the Step 2's.

#2. Why are you launching so high on the 2 step? You're building boost with that 2 step...and launching the piss outta that thing...How much boost are you running out of the hole? I'm suprised you haven't gone through rear end/axles. I would venture to say a more mild launch (5500-6500 range) would be more beneficial on your drivetrain/valvetrain. Is your car bogging if you don't rev it to the 6900-7K+ range? I'm really not sure of what a good "fix" would be for eliminating your problem except for switching to solid lifters....and i've heard that they're tough to get right...

[Blown240sx]

why the hell are you launching at such a high rpm.... I mean geez

[180fan]

I don't recall seeing a lash killer kit being listed on your setup. If you're running a lash killer kit with a step two, there's one fault there. You're supposed to use the HKS step 3, or Toda or Tomei Procams or JUN's cams (solid).

[Nismo_Freak]

C'mon people read his post.

1. He isn't running a "lash killer kit" aka solid lifters.

2. He launches that high because he has an aftermarket management that allows him to, obviously he is on some level of tire.

3. Launching at 7200 RPM > 5500 RPM

You can try upgrading the rockers to the superior stock design.

[SILVIADRIFTR]

Running 26x10.50 et streets or similar size slicks. I have to launch that high to keep the motor in it's optimal power range. I am building anywhere from 15-20psi off the line. If I launch at a lower rpm the 2 step seems to be more harsh than a higher rpm launch. You can't pull a 1.57 60ft with less than 6900rpm's or at least I haven't been able to. I am not running the lash killer kit but was esentially wondering if anyone had tried running them with a step 2 cam instead of the step 3. Excuse my ignorance, but which design is a superior stock design. I thought all the s13,s14,s15 rocker arms were the same. I am going to pick up 8 new factory nissan rocker arms from nissan today. I ordered them for the 91-98 sentra ser 2.0l. I asked a couple of my sources if there was an upgraded rocker arm that someone offered but no one has been able to help me out there.

[SILVIADRIFTR]

I have the exact same setup in my head as you do...everything is the same. This may not be of much help, but it's what I understand.

#1. From what I've heard, the lash killer kit is trash...The people that have told me this haven't gone into detail about why it is...but they are very reputable SR guys so I trust them. Also, I have heard the same thing about the lash killer kit not working with the Step 2's.

#2. Why are you launching so high on the 2 step? You're building boost with that 2 step...and launching the piss outta that thing...How much boost are you running out of the hole? I'm suprised you haven't gone through rear end/axles. I would venture to say a more mild launch (5500-6500 range) would be more beneficial on your drivetrain/valvetrain. Is your car bogging if you don't rev it to the 6900-7K+ range? I'm really not sure of what a good "fix" would be for eliminating your problem except for switching to solid lifters....and i've heard that they're tough to get right...

I have the 300z trans hat has been adapted to my car and have done some other upgrades to the subframe. I talked with one of teh crew from enjuku for their drag car and he let me in on some of the issues I would face.

yes, the car will bog if it doesn't stay in the power band of the turbo since the car hooks at launch.

[Fireplug]

I have the 300z trans hat has been adapted to my car and have done some other upgrades to the subframe. I talked with one of teh crew from enjuku for their drag car and he let me in on some of the issues I would face.

yes, the car will bog if it doesn't stay in the power band of the turbo since the car hooks at launch.

I'm sorry if I came off as criticising you, I didn't mean it that way. If it hooks that hard at launch do you think it's too much of a slick for the car/car's power? Maybe you could go to a MT 8.5-10" slick so it won't hook as hard and get better results with your times, a few guys I talk to have some MT 8.5" slicks and he's running 11.1's-11.0's on them. That might be a route to go, that way with a little spin you'll be easier on your valvetrain and it won't bog = faster times. It seems to me that launching that high is going to keep doing that to the rocker arms but I'm not sure. Try the new ones you got and let us know. I'm interested to see how this turns out.

C'mon people read his post.

2. He launches that high because he has an aftermarket management that allows him to, obviously he is on some level of tire.

3. Launching at 7200 RPM > 5500 RPM

I'm well aware that the 2 step "allows" him to do so, but I was questioning if a 69-7700 launch was beneficial...that's why I asked if he was bogging at any lower launches. I wasn't trying to rip him apart, simply asking a question to figure out why he had to launch so high. and a 7200 launch is not always > then a 5500 launch...It actually depends on the persons setup. Don't tell me a 7200 launch (assuming the drivetrain is setup for it) is going to be better on a stock SR with bolt-ons.


Modified by Fireplug at 9:52 AM 5/18/2005

[USsil80]

You can try upgrading the rockers to the superior stock design.

the only thing that i have seen for rocker arms are the stoppers..you are using them are you not... also contact AEBS they modded there rocker arms some how ... maybe they well let you in on what they did...been to lazy and the car is to far apart then together to call them my self

[SILVIADRIFTR]

I'm sorry if I came off as criticising you, I didn't mean it that way. If it hooks that hard at launch do you think it's too much of a slick for the car/car's power? Maybe you could go to a MT 8.5-10" slick so it won't hook as hard and get better results with your times, a few guys I talk to have some MT 8.5" slicks and he's running 11.1's-11.0's on them. That might be a route to go, that way with a little spin you'll be easier on your valvetrain and it won't bog = faster times. It seems to me that launching that high is going to keep doing that to the rocker arms but I'm not sure. Try the new ones you got and let us know. I'm interested to see how this turns out.

I'm well aware that the 2 step "allows" him to do so, but I was questioning if a 69-7700 launch was beneficial...that's why I asked if he was bogging at any lower launches. I wasn't trying to rip him apart, simply asking a question to figure out why he had to launch so high. and a 7200 launch is not always > then a 5500 launch...It actually depends on the persons setup. Don't tell me a 7200 launch (assuming the drivetrain is setup for it) is going to be better on a stock SR with bolt-ons.

Modified by Fireplug at 9:52 AM 5/18/2005

No offense taken. It does run better with the et streets since it spins instead of hooks but I have to run it up to around 6500 to get them to spin. Maybe we'll play with the tire pressures a little as well. I did run the 1.57 spinning the et streets so that may be better for me than hooking. It ran 11.22 at the end of last year with right at 400whp with the et streets and 1.65 60ft so I will probably try the smaller slick and maybe go with a smaller width on the slick. But I still can't figure out why the rockers would come out unless it is geting valve float at high rpms on the 2 step from it being so harsh.

[SILVIADRIFTR]

the only thing that i have seen for rocker arms are the stoppers..you are using them are you not... also contact AEBS they modded there rocker arms some how ... maybe they well let you in on what they did...been to lazy and the car is to far apart then together to call them my self

It says http://www.aebsracing.com account is suspended. Anybody have their phone number by chance????????????

[SILVIADRIFTR]

Well, I got off the phone a little while ago with HKS and the word on the lash killer kit is that you can run the kit with any of the different step cams they offer. The only one they require use for it with is the step 3, but it will work. So i guess I will try that and bronze valve guides and see how it goes. If anyone else has any input please let me know. Thanks

[USsil80]

what is the advatige of the broze valve guides

[Fireplug]

But I still can't figure out why the rockers would come out unless it is geting valve float at high rpms on the 2 step from it being so harsh.

That's exactly what I thought. That's the only reason in my head it would be doing that. Awesome to hear that the lash killer kit works with any step, I was told it wouldn't...but that was from the grapevine..not HKS. Stick those babies in and let me know how they go. I heard they're noisy...Please keep us informed!

[180fan]

what is the advatige of the broze valve guides

The bronze/phosphor guides holds oil better than the normal bronze.

[Nismo_Freak]

the only thing that i have seen for rocker arms are the stoppers..you are using them are you not... also contact AEBS they modded there rocker arms some how ... maybe they well let you in on what they did...been to lazy and the car is to far apart then together to call them my self

There are at least 3 different versions of the SR rocker from the factory.

[SILVIADRIFTR]

There are at least 3 different versions of the SR rocker from the factory.

So are they different per application or is it from oldest to newest on production? Any idea? I am buying a whole new set.

[justmerging]

Have you considered cryo-treating the rockers. I don't really know much about the process or if it can even be done on your valvetrain but from what I understand it basically "adjusts" the composition of the metal so that they are beefier. Maybe someone else has more imput on this, help me out.

[VitaminT]

Keep in mine at least with Tomei that they sell cams specifically for either solid or hydro lifters. I guess HKS doesn't do this from what the guy you talked to said.

[SILVIADRIFTR]

Have you considered cryo-treating the rockers. I don't really know much about the process or if it can even be done on your valvetrain but from what I understand it basically "adjusts" the composition of the metal so that they are beefier. Maybe someone else has more imput on this, help me out.

One thing I do know is the metal the rocker arms are made of are tiny pieces of metal that are pressed together. If you have ever seen one break you con tell. I don't think cryo-treating them will help when the rocker arm shoot out of it's seat and wedges itself beteen a cam and a valve sideways.

[s13sr20chris]

rocker arms appear to be sintered. mike k made his own lash killer/solid lifters by drilling out the plunger and shimming with pieces of feeler guages.

[ItzGenX]

The rocker arms are made out of cast iron. Like anything cast, when breaking, it looks very much like grains. I would like a better option on rocker arms also. It is something no one put a lot of thought into to produce, but it is a common problem among SR's. I was planning on switching my valvetrain to tomei solid lifters and cams (if I could ever find a way to measure, can't find a shimming tool). Doing the change, I did notice that the new weak point in the valvetrain will become the rockers themselves. However, I think the solid type cams will help prevent breakage due to the softer initial ramp angle on the cam lobe.

[SILVIADRIFTR]

I have figured out some of the answers and figured I would pass them on to you guys.

1. Can you use a solid lifter with a hydrolic rated cam? Yes you can, but you can not run a Hydrolic lifter with a solid cam.2. have yet to be able to find anyone who produces aftermarket or upgraded rocker arms to the public.3. With solid lifters, per HKS, you should have .01-.02 clearance. .015 is optimal.4. With HKS 272 step 2 cams you cannot run a 2 step over 6500rpm without solid lifters.5. Bronze valve guides allow the valves to slide more easily, and creates less stress for the valve train and allows for more hp to be produced.

Thanks for the input guys. The car should be running in about 2 weeks so I will give you an update when I have one.

[s13sr20chris]

sorry, thread jack...hey genx,whats the story on your jgy screwup? if you already posted about it, how about a link?

[FAST-DATSUN]

Hks lash killer, cryo'd rockers are the only cure and at that Drag Racing your still going to break a few with the 272 cams. Make sure your lash pad clearance is DEAD ON and Check spring tension off seat pressure to insure ALL valves are the SAME>>>>>>>

[ItzGenX]

sorry, thread jack...hey genx,whats the story on your jgy screwup? if you already posted about it, how about a link?

I will never deal with JGY ever again. The only thing that I have from their handy work that really never gave me a problem is their fuel rail. Everything else was sent to the recycling center.

zerothread?id=112095

[Florida240sx]

Buddy mark had similiar problems..One thign you could do is get them cryo treated.Think it said is was going to be $2/rocker arm.

[f150intally]

this has been a problem for a long time with the sr. Two of my friends, Enthalpy and TNT, both popped rocker arms off at high rpms. Its not a matter of the rocker arm breaking. The problem is it pops off and that can cause it to break. Do some research, this has been discussed a lot.

as far as launching at 6900 rpm, you need to reconsider your tire sizes. TNT went 10.50 with a 1.65 60 ft and he didn't launch that high.

also, derek greaser cut a 1.49 60 ft with only 385whp and when 10.90. He landed the car in peak torque at around 5500rpm. he was using anti-lag and building 15psi on the line.

Check out my article on launching the 240sx.

[SILVIADRIFTR]

this has been a problem for a long time with the sr. Two of my friends, Enthalpy and TNT, both popped rocker arms off at high rpms. Its not a matter of the rocker arm breaking. The problem is it pops off and that can cause it to break. Do some research, this has been discussed a lot.

as far as launching at 6900 rpm, you need to reconsider your tire sizes. TNT went 10.50 with a 1.65 60 ft and he didn't launch that high.

also, derek greaser cut a 1.49 60 ft with only 385whp and when 10.90. He landed the car in peak torque at around 5500rpm. he was using anti-lag and building 15psi on the line.

Check out my article on launching the 240sx.

I have read the article before. I did try launching at a lower rpm(around 6200) but the car would bog with 350whp. I think this may be related to the Unorthodox crank pulley that I am running, but haven't had a chance to swap back to the stock pulley to find out. The video in my sig is a launch at 6800 rpm but on 26x10.50 et streets with around 360whp. The car pulled a 1.61 60ft . I think another problem I have is the suspension. I have tein he coilovers on the car and the shocks are set at the softest setting in the front and the rear. I am not having a problem hooking with the slicks(26x10.50 etdrags) just keeping it from bogging at a lower rpm. My last 60ft, before the car went down, was a 1.57 60ft spinning the et streets with no antilag and 10lbs off the line. I run a 300zx trans that was modded into the car and since have had no problems with trans failure. I also don't run a clutch that has any slippage. I run the stage4 twin plate exedy(very harsh). One thing I would like to know is what rpm did Derek Greaser launch at to have the rpm's fall to 5500? And also what clutch he was running? Because even though you don't slip a clutch with the pedal, most single plate clutches holding anything over 300 whp have some type of slippage from pressure plate to disc. You also said I need to reconsider my tire size's. What tire sizes are suggested?

[f150intally]

where does your car make peak tq? in the article I mentioned that this varies depending on cam selection etc. Put your car on the dyno and find out where your peak torque is. Then, find out where you need to launch at to achieve that. if you are running 272 step 2s then maybe your peak torque is at 6k. If so then you are probably landing in your peak torque range. Especially if your 60 fts are so good.

As far as tire size, 26s will require you to launch at a high rpm like you have discovered. with some 24" or 24.5" tires you will be able to launch at a lower rpm and maybe not be popping rocker arms.

I will say of the two cars that I have heard of popped rocker arms on, neither one of them were launching. I was riding in one of them and the owner was feathering the clutch in 1st gear.

I have a friend with a 586whp RB (RBTally) who posts here that launches around 6k with 26" slicks but he has more torque being that it is an inline 6. he went 11.11 at 127mph with a 1.65 60 ft.

As far as DG, i'm not sure where he launched at but I know it wasn't 7k. His technique is the same as mind where you "land" right before peak torque.

BTW, what was the time posted in the video??? It looks like you were spinning quite a bit. What air pressure were you running in the tires?

Here is a setup similar to yours. This guy is running 26" MT Streets with 350whp. I think his 60 ft time was 1.6x. He was launching around 5500-6k..

350whp = 11.71et

Here is the RB i was talking about.
Modified by f150intally at 6:54 PM 7/3/2005