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dumb question
https://www.ausmini.com/forums/viewtopic.php?f=2&t=39338		 Page 1 of 1
Author:  mattsmadmini [ Sun Feb 17, 2008 7:46 pm ]
Post subject:  dumb question
as title suggests, pretty dumb question,

just curious though, how does roller rocker gear work? wat does it do? does it improve performance?

again, dumb question.....
cheers,

matt
Author:  sports850 [ Sun Feb 17, 2008 7:53 pm ]
Post subject: 
From what I understand it reduces friction on the valve's top by letting the rockers tip roll when the angle of it changes while pushing the valve down . I don't know about horsepower gains from them but they mean your valves can open and close easier and quicker which might allow a few more revs (If you lighten your valve train it's the same as putting heavier springs on basically , well in a nutshell anyway , a lot of physics involved ...) and will make things smoother . Be keen to hear from anyone with dyno figures comparing roller rockers with fixed rockers of the same offset ???
Author:  Morris 1100 [ Sun Feb 17, 2008 7:57 pm ]
Post subject: 
As a normal rocker opens the valve the tip of the rocker arm slides across the tip of the valve and tries to push the valve sideways as the valve opens, this creates a bit of friction in the valve guide.
Rockers with roller tips do not add any side load to the valve as it opens, this will free up a small amount of friction.
Rockers with needle rollers in the centre bush reduce friction where they run on the rocker shaft.
So if you get rocker arms with needle rollers and roller tips you can reduce a fair bit of friction.

But they do not like small bits of metal in the oil. The sort of small bits that Mini gearboxes give off. :lol:
Author:  1071 [ Sun Feb 17, 2008 8:18 pm ]
Post subject: 
Morris 1100 wrote:
As a normal rocker opens the valve the tip of the rocker arm slides across the tip of the valve and tries to push the valve sideways as the valve opens, this creates a bit of friction in the valve guide.
Rockers with roller tips do not add any side load to the valve as it opens, this will free up a small amount of friction.
Rockers with needle rollers in the centre bush reduce friction where they run on the rocker shaft.
So if you get rocker arms with needle rollers and roller tips you can reduce a fair bit of friction.

But they do not like small bits of metal in the oil. The sort of small bits that Mini gearboxes give off. :lol:


But hopefully you've fitted an oil filter, so the rockers won't see any chunky bits..

You generally use roller rockers which have higher lift. Higher lift increases the side load on the valves leading to premature guide wear, which in turn allows the valve to slop around on its seat reducing its sealing ability.

So, you fit rollers not to increase hp, but rather to retain what you have longer....

Cheers, Ian
Author:  drmini in aust [ Sun Feb 17, 2008 9:22 pm ]
Post subject: 
There are roller rockers, and there are roller rockers. I've seen cheapo Mini***** ones a while back wear flats on the rollers in 10,000km, making them worse than useless.
And cheap alloy ones in race motors flex.
You get what you pay for. You can pay $800+ for good ones.
Many racers still run 1.5:1 forged MSC rockers, or modified Toyota Corolla ones. Reason- they work, and don't break easy. :wink:
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