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  1. #1
    Smartin Guest

    Default What do Roller Rockers Accomplish?

    I've heard and seen everyone use them, but what do they really do for you? Cut down on friction? Do they add HP? I couldn't see any way they could with just bolting them on.

  2. #2
    Join Date
    Oct 2002
    Location
    East Coast
    Posts
    1,117

    Default

    I see the advantages of roller rockers as:
    • Generally more durable with a longer service life
    • Advantage of various ratios available
    • Can increase or decrease lift of same cam depending on rocker ratio
    • Ensures cam specifications are applied in engine
    • Able to compensate for machine work to the head and block
    • Able to compensate for different head gasket thickness
    • Eliminates necessity of adjustable pushrods (relatively weaker)
    • Allows for consistent preload on lifters and adjustment for maximum performance
    • Allows greater lift and spring pressure for bigger or aggressive cams
    • Less chance of catastrophic rocker failure (especially in performance applications)
    • Will allow the use of solid or roller camshaft grinds and lifters (oh yaaaaa!)
    • Less friction and wear on the rest of the valvetrain


    Cheryl
    12 Nissan Leaf SL (100% Electric Vehicle)
    05 Toyota Prius
    95 Suburban Turbo Diesel 2500

  3. #3
    Join Date
    Feb 2002
    Location
    Oakland Gardens, N.Y.
    Posts
    21,667

    Default

    Adam,
    Less friction, better adjustability, stronger, those are the main reasons. The rocker tips have rollers which roll along the valve stem tops instead of rubbing.
    Larry
    1998 "Fully Optioned" SC3800 Riviera
    70 GS 455 Stage1, TSP 470, 602 HP@ 5900, 589 TQ @ 4900
    TA Hyd Roller Cam, 230*/238*, 112, .544"/.577" lift, 4-7 swap
    MSD Digital 6+, Ignitionman Distributor w/MSD trigger
    1967 BT Switchpitch ST-400, Gear Vendors OD
    with TSP 3200/1800 converter
    AED 1000 HO Carb, 800 CFM 7042240 Quadrajet
    8.5 10 bolt, 3.73's
    11.67 @ 115.49 MPH
    Larrymta@verizon.net, GSCA #291
    BPG # 1063
    N.E. GS/GN Club Assistant Director

  4. #4
    Smartin Guest

    Default

    Thanks Cheryl and Larry...


  5. #5
    Join Date
    Jan 2003
    Location
    Port Orchard, WA
    Posts
    718

    Default

    Roller rockers provide a couple of benefits, assuming you are using the same ratio as either stamped steel or iron rockers. Typically, rollers are lighter in weight and have measurable friction savings in the valve train. This reduced weight allows more controlled valve action (assuming the use of the same springs) and can allow for either bigger valves, lighter springs or even a bit more radical cam timing. The reduced friction translates to higher HP at the flywheel.
    Think about it this way, would you rather drag 500 lbs of dead weight across concrete, or would you prefer to put wheels on that 500 lbs? Not an exact comparison, but close enough for this example.
    The question of whether or not rollers are stronger than stock rockers is fairly easily answered when discussing typical stamped steel rockers as found in most SB Fords and Chevys, Olds engines and Pontiacs. Think of the rest of the valve train. If you have a fairly radical cam and the stiff springs required to control the valves using this radical cam, it's pretty tough to have the valves move. If you have stamped steel rockers, they can bend and flex if the wall thickness/rocker design isn't up to the effort and force required to move those stiff springs. The rollers are usually stiffer and, having less friction to move them due to the roller fulcrum and the rocker tip rolling across the valve tip rather than being forced to scrape across the valve stem, they flex much less than the stamped steel.
    Another benefit of **quality** rollers is that they are more accurate in ratio in a set of 16 than stockers. The reason is better quality control. It's like assembling an engine with some pistons at .05" dech height, some at .03" and some at .07". If you do the math to see exactly what I am talking about it goes like this:

    Actual cam lobe height: .350
    Actual rocker ratio: 1.6
    Valve lift: .560

    If you have a set of rockers where the biggest ratio is actually 1.62 and the lowest is 1.58 the math goes like this:

    Actual cam lobe height: .350
    Actual rocker ratio: 1.62
    Valve lift: .567

    Actual rocker ratio: 1.58
    Valve lift: .553

    for a difference in lift of .014

    Both rockers would be considered 1.6 ratio rockers. You get the same kind of variations with duration.

    One thing our Buicks have going for them is the shaft mount rockers. Good motion control and a stiffer valve train. This assumes of course that one has good quality rocker shafts and bolts to hold them down with.

    The question to actually answer is whether or not that reduced friction, ratio availability and valve clearance adjustability is something your engine really needs. If so, spend the bucks for a **quality** set of rollers. There is a lot of trash out there claiming to be "equal to so and so, but without the big cost". Remember, if it seems to good to be true, it probably is.
    Phil
    First Buick: 68 Riv GS Red/Black/Black - Gone - But not forgotten
    Next Buick: 1970 GS350 Silver/Black/Black
    Current cars/projects:
    1967 GS400 Under construction
    1970 Olds 442 Under Construction
    1967 Olds Toronado - Needs electrics and window motors to be finished!
    1994 Ford F350 PSD, Longbed, Crew Cab, Dually, 5 Speed - Currently in Diesel Hospital awaiting treatment
    Daily Driver:
    92 Chevy 1/2 Ton

  6. #6
    Join Date
    Feb 2002
    Location
    Camarillo, CA
    Posts
    430

    Default

    They really have the greatest advantage on high rpm motors.
    Tomsriv
    71 Riv

  7. #7
    Join Date
    Mar 2002
    Location
    Midwest
    Posts
    1,173

    Default

    I agree with Tom, I don't think they do much in a street engine. Sounds "cool" when bench racing though. Mike D.

  8. #8
    Join Date
    Jan 2003
    Location
    Port Orchard, WA
    Posts
    718

    Default

    Let's ask Mr. Tri-Shield (Mike)

    Want to weigh in here? Are roller rockers 'worth it' for a street car? At what point would you recommend to a customer that they move up to full roller rockers?

    I ask because even the OEM's are going to rollers, either cams/lifters or rockers on even the lowly Olds 307 that powers my daughter's Chev Caprice wagon.

    Phil
    First Buick: 68 Riv GS Red/Black/Black - Gone - But not forgotten
    Next Buick: 1970 GS350 Silver/Black/Black
    Current cars/projects:
    1967 GS400 Under construction
    1970 Olds 442 Under Construction
    1967 Olds Toronado - Needs electrics and window motors to be finished!
    1994 Ford F350 PSD, Longbed, Crew Cab, Dually, 5 Speed - Currently in Diesel Hospital awaiting treatment
    Daily Driver:
    92 Chevy 1/2 Ton

  9. #9
    Join Date
    May 2002
    Location
    Linden, MI
    Posts
    4,092

    Default

    I just put in a set this summer. Did not expect any HP gains but was able to make sure the preload on the lifters was correct. If/when I change cams will be an easy adjust.
    Doug Gorton
    Gravity, it's only a theory.
    Trying is the first step towards failure
    -Homer Simpson
    GSX clone- May 2002
    Supercharged 462-April 2010
    1973 Ski Nautique 351w
    87 GN- August 2005

  10. #10
    Join Date
    Jul 2002
    Location
    the cold north
    Posts
    818

    Default

    Another thing they will accomplish is too drain your wallet. They cost like 600 or 700 dollars don't they?
    Bob Gable
    70 GS Foe Fiddy 5

  11. #11
    Join Date
    May 2002
    Location
    Linden, MI
    Posts
    4,092

    Default

    TA's do. I would not have them except for getting a deal ($300) about the same as TA rebuilt set.
    Doug Gorton
    Gravity, it's only a theory.
    Trying is the first step towards failure
    -Homer Simpson
    GSX clone- May 2002
    Supercharged 462-April 2010
    1973 Ski Nautique 351w
    87 GN- August 2005

 

 

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