Could someone explain roller rocker arms?
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Joined: Jun 2001
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From: West Dundee IL
Could someone explain roller rocker arms?
Would someone mind explaining the difference between roller rocker arms and regular rocker arms? I have rollers in mine, but I have no idea what it means..
Thanks
Tom :flag
Thanks
Tom :flag
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Joined: Apr 1999
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From: Raleigh North Carolina
Re: Could someone explain roller rocker arms? (tdellaringa)
At the point where the lifter rides on the cam, a regular hydraulic (or solid) lifter has a flat or slightly convex surface. A roller lifter has a roller at this point which rolls on the cam lobe, unlike a standard lifter which "wipes" on the lobe. Hydraulic roller cams have different profiles than non-roller cams.
Also... highly modified engines can have "roller" cam bearings as well. These replace the common shell type bearings. The block and/or cam must be modified to use this setup.
Edit:
Now... to answer your question... I had to hit "reload" 12 times to reply, by the time the box came up, I had forgotten your question!
Roller rockers can be simply "roller tipped", which have a small roller mounted in the tip where it rides on the valve stem tip. These reduce friction greatly and pretty much eliminate "rocker arm scrub" which is the action of the rocker arm tip scraping across the valve tip. This also reduces side loading of the valve in their guides which prolongs the life of the valves, guides, and seals.
Other roller rockers may have the fulcrum where the rocker pivots mounted in roller (needle) bearings as well. This also reduces friction and is worth some HP.
[Modified by Tom454, 2:56 PM 10/5/2001]
Also... highly modified engines can have "roller" cam bearings as well. These replace the common shell type bearings. The block and/or cam must be modified to use this setup.
Edit:
Now... to answer your question... I had to hit "reload" 12 times to reply, by the time the box came up, I had forgotten your question!
Roller rockers can be simply "roller tipped", which have a small roller mounted in the tip where it rides on the valve stem tip. These reduce friction greatly and pretty much eliminate "rocker arm scrub" which is the action of the rocker arm tip scraping across the valve tip. This also reduces side loading of the valve in their guides which prolongs the life of the valves, guides, and seals.
Other roller rockers may have the fulcrum where the rocker pivots mounted in roller (needle) bearings as well. This also reduces friction and is worth some HP.
[Modified by Tom454, 2:56 PM 10/5/2001]
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Joined: Feb 1999
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From: Park Ridge IL
Re: Could someone explain roller rocker arms? (tdellaringa)
There are tow types of roller rockers (not including shaft mounted roller rockers): full roller rockers and roller tipped rockers.
Full roller rocker feature a rollerized trunnion in addition to the roller wheel which rides over the valve stem tip. The elimination of the ball nut used at the pivot point on standard rockers reduces friction significantly.
Roller tipped rockers use the same ball nut as a standard rocker but feature a roller wheel at the tip for riding over the valvestem. There is very little benefit to roller tipped rockers as there is not as much friction on the vlave stem tip as there is at the pivot point. If you consider that a standard valve stem tip has a diameter of 11/32", and a properly set up valvetrain keeps rocker movement within the center 1/3 of the valve stem tip, you should only have about 3/32" movement max across the valve stem tip.
Actually, alot of times, especially when high-performance springs are used, the roller wheel tip on roller rockers doesn't even roll in the real world, it just slides across the valve stem tip.
Full roller rocker feature a rollerized trunnion in addition to the roller wheel which rides over the valve stem tip. The elimination of the ball nut used at the pivot point on standard rockers reduces friction significantly.
Roller tipped rockers use the same ball nut as a standard rocker but feature a roller wheel at the tip for riding over the valvestem. There is very little benefit to roller tipped rockers as there is not as much friction on the vlave stem tip as there is at the pivot point. If you consider that a standard valve stem tip has a diameter of 11/32", and a properly set up valvetrain keeps rocker movement within the center 1/3 of the valve stem tip, you should only have about 3/32" movement max across the valve stem tip.
Actually, alot of times, especially when high-performance springs are used, the roller wheel tip on roller rockers doesn't even roll in the real world, it just slides across the valve stem tip.
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From: Foxfield CO 1970 Convertible
Re: Could someone explain roller rocker arms? (tdellaringa)
