Broken rocker arm, tossed spring shim. RAS? Cams? Or hard limiter? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

KingSpence · 05-31-2014, 02:48 AM

Stock head, so stock springs, retainers, hydraulic lash adjusters. BC 264 IN/EX camshafts. Tomei RAS. Hard limiter set to 7200rpm. 355whp/298tq 14psi.

I'm a noob to this site, but it's a great forum with a plethora of information.

I have an odd powerband, it doesn't peak before redline, it keeps going. This is causing me to be on the upper end of the rpm range, ALL THE TIME.

4500rpm--170hp
5000rpm--260hp
5500rpm--300hp
6000rpm--325hp
7000rpm--355hp

Within 100kms of driving I broke a rocker arm in three pieces. Cylinder #1 exhaust rocker. Tonight as I shifted from first, I hit limiter as my clutch went in, loud backfire, tossed a shim from exhaust rocker #4.

I'm frustrated, and trying to get an idea on what the issue is. I've heard good things, and bad things about RAS, sound like I shouldn't be running them with a stock head. BUT, is this and issue that can be caused by not running stiffer springs in the first place?

I've also heard a hard limiter can be the cause of these issues? What's the advantages, and disadvantages of a hard limiter?

What should I change, what should I keep? I can't have this thing breaking constantly. I spent two hours in a parking lot tonight pulling a camshaft.

Here's a picture of the car we're talking about. Thanks guys!

jr_ss · 05-31-2014, 09:56 AM

Factory springs with BC cams would be the start of where I'd look. You need springs with an upgraded cam shaft in the step 2 range.

Doing the dual guide mod will help as well. That's where I would start.

Asil · 05-31-2014, 10:18 AM

I was reving the same 7.200 and i have broken rocker arms two times. Then, put the limit on 6.900 and i never break again. Also there was an option of "soft limiter" on the AEM ecu.
Hard reving especially at first gear breaks the rockers.
And i think RAS is a must otherwise you will easily throw rocker even at lower rpms only good thing maybe you dont brake it.

EsChassisLove · 05-31-2014, 10:23 AM

I've only broken one in two years of having 400+hp, Tomei 272 cams, Tomei RAS and Tomei dual valve spring kit.

They just break.

cotbu · 05-31-2014, 02:43 PM

I'd like to say that most people don't understand what hard and soft cut limiters are. The aem unit is blamed for broken thrown rocker arms but it shouldn't be. The stock ecu has the same cuts. The fuel cut is referred to as soft and the hard cut is ignition.

That being said you setup is not correct, why? bc recommends springs with their step 2 264 cams. And you don't have them.
If you think this is happening at the hard cut, raise it, turn it off, or make the soft cut closer to the hard cut in rpm. it may lesson the shock to the valve train

Kingtal0n · 05-31-2014, 06:28 PM

its your weak springs.

doctors recommend wearing a condom to prevent some sexually transmitted diseases. Do you walk into a clinic and say "well it cant be an std because condoms are just recommended..."

Croustibat · 06-01-2014, 02:07 PM

You really have heard good things about RAS ? I have seen heads DESTROYED by RAS, but i never saw one SAVED by these.

You need to understand that they dont prevent the engine from throwing a rocker arm, they prevent the rocker arm from moving out of the way. What do you think happens when a rocker arm gets sideways there ? yup, valves go making a last kiss to the piston under, and it also tend to kill the cam lobes.

Stay away from that RAS crap, get a lower rev limit, or a newer/ tighter head. And harder springs ...

05-31-2014, 09:56 AM	#2
jr_ss Post Whore! Join Date: Dec 2005 Location: Pa Posts: 6,415 Trader Rating: (35) Feedback Score: 35 reviews	Factory springs with BC cams would be the start of where I'd look. You need springs with an upgraded cam shaft in the step 2 range. Doing the dual guide mod will help as well. That's where I would start. __________________ My SR20VET Does your VTC gear rattle in your S14/15 SR? PM me.

05-31-2014, 02:43 PM	#5
cotbu Post Whore! Join Date: Sep 2005 Location: SWFL Age: 50 Posts: 3,318 Trader Rating: (3) Feedback Score: 3 reviews	I'd like to say that most people don't understand what hard and soft cut limiters are. The aem unit is blamed for broken thrown rocker arms but it shouldn't be. The stock ecu has the same cuts. The fuel cut is referred to as soft and the hard cut is ignition. That being said you setup is not correct, why? bc *recommends* springs with their step 2 264 cams. And you don't have them. If you think this is happening at the hard cut, raise it, turn it off, or make the soft cut closer to the hard cut in rpm. it may lesson the shock to the valve train __________________ LoverTechnologies "Half Broken Things!"

05-31-2014, 06:28 PM	#6
Kingtal0n Post Whore! Join Date: Jul 2005 Location: South Florida Age: 42 Posts: 4,829 Trader Rating: (17) Feedback Score: 17 reviews	its your weak springs. doctors recommend wearing a condom to prevent some sexually transmitted diseases. Do you walk into a clinic and say "well it cant be an std because condoms are just recommended..." __________________ 5.3/4l80e/turbo 240sx playthrough: tinyurl.com/4l80er

05-31-2014, 02:48 AM	#1
KingSpence Join Date: Feb 2012 Location: Edmonton, AB Age: 34 Posts: 30 Trader Rating: (0) Feedback Score: 0 reviews	Broken rocker arm, tossed spring shim. RAS? Cams? Or hard limiter? Stock head, so stock springs, retainers, hydraulic lash adjusters. BC 264 IN/EX camshafts. Tomei RAS. Hard limiter set to 7200rpm. 355whp/298tq 14psi. I'm a noob to this site, but it's a great forum with a plethora of information. I have an odd powerband, it doesn't peak before redline, it keeps going. This is causing me to be on the upper end of the rpm range, ALL THE TIME. 4500rpm--170hp 5000rpm--260hp 5500rpm--300hp 6000rpm--325hp 7000rpm--355hp Within 100kms of driving I broke a rocker arm in three pieces. Cylinder #1 exhaust rocker. Tonight as I shifted from first, I hit limiter as my clutch went in, loud backfire, tossed a shim from exhaust rocker #4. I'm frustrated, and trying to get an idea on what the issue is. I've heard good things, and bad things about RAS, sound like I shouldn't be running them with a stock head. BUT, is this and issue that can be caused by not running stiffer springs in the first place? I've also heard a hard limiter can be the cause of these issues? What's the advantages, and disadvantages of a hard limiter? What should I change, what should I keep? I can't have this thing breaking constantly. I spent two hours in a parking lot tonight pulling a camshaft. Here's a picture of the car we're talking about. Thanks guys!

05-31-2014, 10:18 AM	#3
Asil Join Date: Sep 2012 Location: Istanbul Age: 39 Posts: 36 Trader Rating: (2) Feedback Score: 2 reviews	I was reving the same 7.200 and i have broken rocker arms two times. Then, put the limit on 6.900 and i never break again. Also there was an option of "soft limiter" on the AEM ecu. Hard reving especially at first gear breaks the rockers. And i think RAS is a must otherwise you will easily throw rocker even at lower rpms only good thing maybe you dont brake it.

05-31-2014, 10:23 AM	#4
EsChassisLove Nissanaholic! Join Date: Jan 2011 Location: San Diego Age: 36 Posts: 2,090 Trader Rating: (26) Feedback Score: 26 reviews	I've only broken one in two years of having 400+hp, Tomei 272 cams, Tomei RAS and Tomei dual valve spring kit. They just break. __________________ IG/TikTok-ThatS14_Z06guy

06-01-2014, 02:07 PM	#7
Croustibat Nissanaholic! Join Date: Aug 2011 Location: France - Toulouse Age: 44 Posts: 1,851 Trader Rating: (0) Feedback Score: 0 reviews	You really have heard good things about RAS ? I have seen heads DESTROYED by RAS, but i never saw one SAVED by these. You need to understand that they dont prevent the engine from throwing a rocker arm, they prevent the rocker arm from moving out of the way. What do you think happens when a rocker arm gets sideways there ? yup, valves go making a last kiss to the piston under, and it also tend to kill the cam lobes. Stay away from that RAS crap, get a lower rev limit, or a newer/ tighter head. And harder springs ...