Mark VI Big block cam swap question

Discussion in 'Engine Topic' started by Powerglide350, Jul 8, 2015.

  1. Damon

    Damon Veteran Member

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    Nov 16, 2000
    Philly area
    Pay attention with those Comp 914 springs. They only work on Krabben's motors because it's a 454HO crate engine with old school rectangular port heads- traditional 1.88" spring installed height, non-rotator/retainers and a partridge in a pear tree. (They were a Team-Damon special selection to fit his specific application as a drop-in upgrade)

    I have NO IDEA what the spring installed height is on a factory L29 head. If it's 1.88", and the factory spring pockets can accomodate them, they'll probably work just fine for you. If it's not, you could be asking for trouble. Valve springs are HEAD-SPECIFIC as well as cam-specific if you're looking for drop-in simplicity.
     
    Last edited: Jul 8, 2015
  2. Powerglide350

    Powerglide350 Veteran Member Lifetime Gold Member

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    Jul 8, 2001
    Moriches,NY
    It seems most people are using rotator eliminators, apparantly some minor grinding is required to make them sit flat.
     
  3. Damon

    Damon Veteran Member

    12,937
    21
    Nov 16, 2000
    Philly area
    Understood. Big block heads got all kind of weirdness thrown at them over the years. Rotator/retainers or standard retainers with rotators that sit down in the valve spring seat.... it's a bit nightmarish when you drill down into the details on any given head.

    Figure out what your ACTUAL spring installed height is going to be once you have selected what your final parts are going to be in the valvespring area. Eliminating the rotators can make a BIG difference in your installed height. Then we can get down to brass tacks on what springs will work.

    There is no simple shortcut in this area. You choose, you measure, you figure out what's going to work.
     
  4. Powerglide350

    Powerglide350 Veteran Member Lifetime Gold Member

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    Jul 8, 2001
    Moriches,NY
    Ugh. I was just hoping for a tried and true combo. The motor I have is all stock. I agree that the right way to do it would be to measure everything out. I just figured someone must've had the same idea as me with the same engine. Just trying to eliminate the chance of screwing it up, this will be my first big block build. The small block stuff I've done was more or less idiot proof.
     
  5. curtscam

    curtscam Member

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    Apr 22, 2012
    Cookeville,tennessee

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