Modified XJ Cherokee Tech XJ (84-01)
All modified tech questions. If it modifies your XJ beyond stock parts ask it here.

Roller rockers

Old 04-22-2017, 09:16 PM
  #1  
Junior Member
Thread Starter
 
lild's Avatar
 
Join Date: May 2015
Posts: 47
Likes: 0
Received 0 Likes on 0 Posts
Default Roller rockers

So I seen a video today trying to say roller rocker arms gain 20+ hp is this true I find it hard to believe but I would like to know if it's worth the money.
lild is offline  
Old 04-22-2017, 09:26 PM
  #2  
Member
 
Jeepification's Avatar
 
Join Date: May 2013
Location: Ohio
Posts: 155
Likes: 0
Received 0 Likes on 0 Posts
Year: 2001
Model: Cherokee
Engine: 4.0L non 0331 head
Default

Originally Posted by lild View Post
So I seen a video today trying to say roller rocker arms gain 20+ hp is this true I find it hard to believe but I would like to know if it's worth the money.
So the video you SAW was potentially correct assuming every other thing in the engine is in tip top shape and probably has other performance parts on it.
Jeepification is offline  
Old 04-22-2017, 10:11 PM
  #3  
Junior Member
Thread Starter
 
lild's Avatar
 
Join Date: May 2015
Posts: 47
Likes: 0
Received 0 Likes on 0 Posts
Default Fresh

Well I have a fresh rebuild, with a port and polished head, heavier valve springs, bigger cam, header, and a few other new things, next i was looking at injectors and maybe roller rockers. If it's worth the time and money.
lild is offline  
Old 04-22-2017, 10:19 PM
  #4  
Member
 
Jeepification's Avatar
 
Join Date: May 2013
Location: Ohio
Posts: 155
Likes: 0
Received 0 Likes on 0 Posts
Year: 2001
Model: Cherokee
Engine: 4.0L non 0331 head
Default

Originally Posted by lild View Post
Well I have a fresh rebuild, with a port and polished head, heavier valve springs, bigger cam, header, and a few other new things, next i was looking at injectors and maybe roller rockers. If it's worth the time and money.
I'd say that with your application, definitely yes.
Jeepification is offline  
Old 04-24-2017, 08:30 AM
  #5  
Senior Member
 
TRCM's Avatar
 
Join Date: Jan 2016
Location: Newport News, VA
Posts: 949
Likes: 0
Received 0 Likes on 0 Posts
Year: 96 & 88 4 dr Cherokees
Default

20 hp sounds a little excessive...but it can't hurt.
TRCM is offline  
Old 04-24-2017, 08:41 AM
  #6  
CF Veteran
 
Join Date: Apr 2016
Location: Pasquotank, NC
Posts: 1,606
Likes: 0
Received 0 Likes on 0 Posts
Year: 1990
Model: Cherokee
Engine: 4.0
Default

The rocker arms are a simple lever. The ratio between the point the lifter presses to the pivot point and the point the rocker presses on the valve increases the distance the valve is opened. Follow me? Here's a link to better explain what I mean: http://www.jegs.com/s/tech-articles/...atio+Explained Increase the ratio, increase how much the valve opens.

That said, the roller end simply reduces the friction in the drivetrain. That's definitely good, but doesn't increase power. Do not buy roller rockers in the same ratio as what you have because you will see no power increase. Before buying a higher ratio, verify you will not have clearance issues. I am not sure about jeep engines, haven't messed with them before, BUT I know LS1s you must be VERY careful with the amount of lift on a cam and higher ratio rockers because you can slam a valve into a piston. The correct way to identify clearances is to put clay on the top of the piston, rotate engine, and check for impressions in the clay. There are other ways to check for clearance, I suggest Google.
bad_idea is offline  
Old 04-24-2017, 09:01 PM
  #7  
Senior Member
 
TRCM's Avatar
 
Join Date: Jan 2016
Location: Newport News, VA
Posts: 949
Likes: 0
Received 0 Likes on 0 Posts
Year: 96 & 88 4 dr Cherokees
Default

Been there...done that (clay checks)

Gotcha....but the original post mentioned nothing about changing the ratio too.....my comment was on just using roller rockers to get rid of the friction and gain a slightly stiffer rocker assembly.

Changing the ratio too can add hp......until ya smack a piston top....
TRCM is offline  
Old 04-24-2017, 10:50 PM
  #8  
CF Veteran
 
Join Date: Apr 2016
Location: Pasquotank, NC
Posts: 1,606
Likes: 0
Received 0 Likes on 0 Posts
Year: 1990
Model: Cherokee
Engine: 4.0
Default

I know the OP didn't mention a ratio change, I wanted to educate if he was unaware or anyone else reading. It is my understanding changing to roller rockers (same ratio) will net a more reliable valve train but will not net noticeable horsepower increases. To net horsepower you must increase the ratio also.

Many modifications people neglect to mention important details. I feel this may be one of those situations. If someone claims noticeable horsepower increase from roller rockers, I believe they changed the ratio also and neglected to mention it. Similar to changing to 4 hole injectors, was it the injector type change that increased power or the fact the old ones were filthy and leaking? Similar to claiming a Holley carburetor increased throttle response and power over a Rochester that was on the engine, when in reality they added a 600 CFM 4 barrel in place of the Rochester 2 barrel that's maybe 300 CFM.
bad_idea is offline  
Old 04-25-2017, 11:58 AM
  #9  
Senior Member
 
TRCM's Avatar
 
Join Date: Jan 2016
Location: Newport News, VA
Posts: 949
Likes: 0
Received 0 Likes on 0 Posts
Year: 96 & 88 4 dr Cherokees
Default

Originally Posted by bad_idea View Post
I know the OP didn't mention a ratio change, I wanted to educate if he was unaware or anyone else reading. It is my understanding changing to roller rockers (same ratio) will net a more reliable valve train but will not net noticeable horsepower increases. To net horsepower you must increase the ratio also.

Many modifications people neglect to mention important details. I feel this may be one of those situations. If someone claims noticeable horsepower increase from roller rockers, I believe they changed the ratio also and neglected to mention it. Similar to changing to 4 hole injectors, was it the injector type change that increased power or the fact the old ones were filthy and leaking? Similar to claiming a Holley carburetor increased throttle response and power over a Rochester that was on the engine, when in reality they added a 600 CFM 4 barrel in place of the Rochester 2 barrel that's maybe 300 CFM.

Which is why I said 20 HP may be a bit much.....same ratio...nill in the HP department, but you do get a more reliable valvetrain with less deflection

change ratio, maybe 15-20 hp, depending on other stuff.
TRCM is offline  

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: