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  1. #1
    Join Date
    Jan 2009
    Posts
    14

    Default 1.5 to 1.6 rockers

    sbc low lift hyd. cam looking to go to 1.6 rockers for a little more.do i need to change push rod length to. stock steel rockers.

  2. #2
    Join Date
    May 2012
    Posts
    334

    Default

    would not think so. ball to valve would be the same. push rod is moved in to make more lift.

  3. #3
    Join Date
    Dec 2008
    Posts
    174

    Default

    If you don't run guide plates ...the pushrod might rub against the bottom of the hole where the push rod goes through the head if it isn't enlarged already. Double check that after installing.

  4. #4
    Join Date
    May 2007
    Location
    in a van down by the river
    Posts
    1,892

    Default

    need to check pushrod length by installing and setting the lash on #1 cylinder. exhaust, then intake.
    note were the roller is riding on surface of the valve. roll engine over threw valve cycle.
    watch the path of the roller rolling across the surface of valve. you want it to stay as close to center as possible through the entire cycle.
    if it starts out just outside center, (toward header side) it should roll through center and max out at the same location on the opposite side of the valve that it started on (intake side).
    like I stated before you want to stay as close to center as possible to reduce side loading of valve stem, and premature valve guide wear.
    I think there should be lifeguards in the genepool.

  5. #5
    Join Date
    Jul 2014
    Posts
    305

    Default

    Leave the 1.5s 👍

  6. #6
    Join Date
    May 2007
    Location
    Pa
    Posts
    486

    Default

    Why not just talk to your cam manufacturer. Most cams are designed and built to run certain rocker arm ratio. You may actually hurt your performance by steering away from recommendation on the cam card. I have never seen any significant change in performance by just changing rocker arm ratio. You may have to change cam degree's to get what you want.

  7. #7
    Join Date
    Sep 2009
    Posts
    831

    Default

    The general rule of thumb for cam design is to open the valve quicker, hold it open longer, close it faster. Doing any of these things without losing the control of the timing event's will net more power.

    Low lift cam and high ratio rockers have an effect of speeding up the valve actions with out the extra weight of the lifter and push rods. You can get roller cam timing event's on a flat tappet cam with higher ratio rockers. The limiting factor is the spring controlling the valve.

  8. #8
    Join Date
    Jul 2014
    Posts
    305

    Default

    Just do 1.5s and mild cam 👍

  9. #9
    Join Date
    Aug 2007
    Posts
    746

    Default

    This is not as simple as just switching rockers. What is the cam specs? What are the motor specs? What are you looking to find or gain and where? What rocker ratio was the cam designed for? I have had engines dynoed that we have swapped the rocker arms in different combinations to find the most usable power band. You may very well end up with something you really don't like.

  10. #10
    Join Date
    Jul 2014
    Posts
    305

    Default

    You'll like a 1.5 vs 1.6 ill put $ on it. I can't tell you no matter what cam we have had in any motor I've had every time we switched to a 1.6 I hated the car. Way to radical every time. Driven a heck of a lot of cars and honesty the last car I drove had 1.6 on intake and I switched to 1.5s after a Thursday night practice and what a difference. Was a dry slick win that night as well. I've been able to feel the tq and car under me so much better when normally 1/2 throttle to 3/4 or full throttle it only felt like a noise maker and nothing changed in the seat of your pants.

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