Safe 360ci valve spring compression height question

Discussion in 'General Motoring' started by Brett, Aug 19, 2003.

  1. Brett

    Brett Guest

    I recently bought a Mopar Performance pre-magnum short block. I am using
    a set of rebuilt stock 1976 heads with stock valves and stock 1.5
    rockers. I put the MP .430 int/.450 ext. cam in there with the exact
    valve springs and everything that MP recommends to be installed with
    this cam. The problem is that the Mopar Engines book lists this spring
    as having a 1.18 soild height and on my engine (and any stock engine)
    the exhaust valves are going to reach 1.20 and the intake 1.22 with this
    setup. The Mopar Engines book state that you should have at least 0.10
    distance between the solid height of the spring and max valve lift and I
    am only left with 0.04 int and 0.02 exhaust (installed spring height
    varies from 1.65-1.67) and this is with using the recomended parts from
    Mopar. Can anyone shed some light on to this?

    Brett, Aug 19, 2003
  2. Brett

    dodgeboy Guest

    First you stock stamped rockers are likely closer to 1.4 to one than the
    advertised 1.5 to 1. I've never seen an RV type cam .430/.450 lift come
    go anywheres near coil bind on a small block!!
    Don't worry be happy.
    Barry A. Lee
    dodgeboy, Aug 19, 2003
  3. Brett

    MoPar Man Guest

    How much is a small-block short block these days? And does it
    _really_ come from Chrysler? (I bought a 318 short block about 16
    years ago from a Chrysler dealership. It was built by a re-builder
    called "Ontario Reman" - had a metal tag pinned to the front of the
    block with the rebuilder's ID)
    MoPar Man, Aug 20, 2003
  4. Brett

    Brett Guest

    The other day I put a solid lifter in the #1 intake and set up for zero
    lash. When I measured the max lift the spring was at 1.21 which is only
    ..03 over the solid spring height of 1.18. Isn't this going to overstress
    the spring? Has anyone built a motor with the springs this close to the
    solid height without problems long term?

    Brett, Aug 21, 2003
  5. Brett

    Brett Guest

    Was about $1,250 before taxes. I think there was something on the box
    the engine came in about being made in Canada but there seems to be alot
    of parts made for Chrysler there. Looks to be a good quality engine I
    just don't want to destroy it with too little spring clearance. I had to
    swap out the .509 lift cam for the smaller one for use with my '76 stock
    heads. Also selling the .509 cam and timing chain set if anyone is

    Brett, Aug 21, 2003
  6. Brett

    dodgeboy Guest

    But how did the coils look! If their is space between then don't worry!
    Barry A. Lee
    Or go to the P5249847 spring.
    If it did not coil bind i wouldn't worry too much. I think your over
    thinking their conservative specks.
    dodgeboy, Aug 21, 2003
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