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Thread: This is good info for us "not so schooled" in engine builing

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    99dart's Avatar
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    Default This is good info for us "not so schooled" in engine builing

    How to Select a Valve Springs; http://www.crankshaftcoalition.com/w.../Crane_pdf.pdf


    With the many choices of aftermarket cylinder heads, most with longer-than-stock length valves, the recommendation of a
    specific spring for a specific cam is almost impossible. It is now necessary to select the spring that will best fit the cylinder
    head configuration. We offer the following as general guidelines only:
    1) “FLAT FACED LIFTER” cam/lifter applications (Street & Street/Strip) seat pressures
    a. Small Block: 105-125# Seat Pressure
    b. Big Block: 115-130# Seat Pressure (Note: Big Block applications need higher seat pressures due to their
    larger, heavier valves.)
    2) “FLAT FACED LIFTER” Open pressures should not exceed 330# open pressure (sustained after spring break-in
    for accepable cam and lifter life.
    a. Open pressures should be a minimum of 220# for applications up to 4000 RPM.
    b. For good performance above 4000, open pressures should be at least 260# with stock weight valves.
    (Lightweight valves require less spring open pressure.)
    c. Spring open pressures over 280# can cause pressed-in studs to come loose; therefore, we recommend
    screw-in studs for open pressures above 280#.
    3) HYDRAULIC ROLLER CAMS require higher spring seat pressures to control the heavier roller tappets and the more
    aggressive opening and closing rates available to roller cam profiles.
    a. Small Block applications: 120-145# seat pressure
    b. Big Block applications: 130-165# seat pressure
    4) HYDRAULIC ROLLER CAMS use higher open pressures to control the high vertical opening inertia of the heavier
    roller followers.
    a. Small Block applications need at least 260# for general driving applications up to 4000 RPM.
    b. Moderate performance small block applications like 300-360# open.
    c. Serious small block applications can tolerate 400-425#* open pressures and still expect reasonable
    valve train life when top quality springs, pushrods, and lubricants are used.
    d. Big Block applications need at least 280# for general driving applications up to 4000 RPM.
    e. Moderate performance big block applications like 325-375# open pressure.
    f. Serious big block performance applications can tolerate 450#* open pressure and still expect
    reasonable valve train life when top quality springs, pushrods, and lubricants are used.
    *Note: Open pressures in excess of 360# require the use of roller tappet bodies made of billet steel. Crane hydraulic roller
    and solid roller tappets are made from heat treated steel billet to withstand the stresses of high-performance use. Most
    stock hydraulic roller tappet bodies are made of cast iron and cannot tolerate high spring loads.
    5) MECHANICAL ROLLER CAM/LIFTER Applications are generally for serious street/strip use and full competition. Most are not used in daily-drivers where day-to-day reliability is stressed. Instead, most of these cams are intended for winning performance. These cams are designed with very aggressive opening and closing rates. High seat pressures are necessary to keep the valves from
    bouncing when they come back to the seat. In all cases, the valve action and spring pressures required mandate the
    use of high-strength, one-piece valves. However, Crane does offer the SR-Series of Street Roller camshafts intended
    for daily usage.
    a. Seat Pressures are determined by valve/retainer weight, engine RPM and life expectancy of components
    before replacement is required. Milder roller cams require 165# on the seat as an absolute minimum.
    180-200# is common for most modest performance applications. 220-250# is common for most serious
    sport categories and some circle track professional categories. Pro-Stock and Blown Alcohol/Fuel drag applications use as much as 340-500# on the seat.
    b. Open Pressures need to be high enough to control the valvetrain as the lifter goes over the nose of the cam. Ideally, the minimum amount of open pressure to eliminate or minimize valvetrain separation is desired. Any
    excess open pressure only contributes to pushrod flex, which can aggravate valvetrain separation. For serious
    racing applications this can be determined only by experimentation and track testing. For general guidelines
    we offer the following
    i. Street/Strip performance with long cam/lifter life desirable, 350-450# open. ii. Circle track and moderate bracket racing 450-600@ open.
    iii. Serious drag racing and limited distance circle track racing 600# and more.
    H
    99 DA CC R/T
    13.97@100 w/modded kegger & ported TB
    12.96 @103
    10:8-1 .30 over forged bottom end
    R/T ported heads
    Detroit locker 4:56 gears
    Built 46RE MSaine 3500 stall Ultra Billet
    http://imgur.com/a/lOVuZ

  2. #2



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    Default

    I called PAC and said..."HELP". Then I let my engine guy set the installed height with +.100 retainers.

    Done.
    11.27 @ 118.23
    2017 NM Mopar Challenge Series Champion

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