Magnum roller camshaft

Small Block Mopar Engine

  1. 6PakBee

    6PakBee FABO Gold Member FABO Gold Member

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    Anyone got an idea how much lift the stock roller lifter spider based retainers can handle? I would think that there is a point where the spider can't control the lifters and you have to go to the link arrangement.
     
  2. George Jets

    George Jets 1967 Dart 2 Door FABO Gold Member

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    Here is a stock '90 318 roller engine for comparison. (TBI setup)

    Imagine it's about the same as the magnum spider setup.

    You could look up the eariler roller lifters like pictured here, then look at the roller lifters for your magnum. See if that flat side on the lifter is longer on your magnum engine. Would think that has a lot to do with how much lift you can run.

    Screenshot_20211125-083945_Gallery.jpg

    Screenshot_20211125-083653_Gallery.jpg

    Also check to see if the lifter bore castings are standing up higher on your magnum engine too. That would help support more lift.
     
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    • pishta

      pishta I know I'm right....

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      measure and multiply by ~1.5 or 1.6 on a magnum. Id say not much but remember the max lift is determined by how much they drop the base circle. That top lifter looks maxed.
       
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      • George Jets

        George Jets 1967 Dart 2 Door FABO Gold Member

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        Here is a magnum roller lifter for comparison:

        Screenshot_20211125-085900_Firefox.jpg

        Screenshot_20211125-085808_Firefox.jpg
         
      • Mopar Sam

        Mopar Sam Well Fed Member

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        How much lift are you wanting to run?

        Two of my sons run the magnum spider setup.

        One runs .575" lift with stock spider setup and stock magnum rockers.

        The other runs .565" lift with the magnum spider and 273 adjustable rockers on edelbrock LA heads on a magnum block.

        The 565 lift cam was .380" lobe lift. If I remember correctly, there was enough room for .400+ lobe lift.

        The size of cam's base circle will make a difference too.

        I hope this helps.
         
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        • Mopar Sam

          Mopar Sam Well Fed Member

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          I forgot to mention, these are their daily drivers, and their only vehicles. Both have proven to be reliable.
           
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          • mopowers

            mopowers Well-Known Member

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            I would think uncovering the oil ring would be a bigger concern than being out of the operating range of the retainer.
             
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            • rumblefish360

              rumblefish360 I have escaped the evil Empire State! FABO Gold Member

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              I don’t think the spider has issues. I think the oil band on the lifter body will, but at what lift I do not know. The lifter bores are much more uniform as compared to the earlier LA engines and much taller. Again, how much lift hey can handle I do not know. But Sam’s kids run a good bit I see.

              If there is any problem to running a high lift, I don’t think you’ll find it at the cam, lifters or spider. The heads, if stock, have lower lift limitations.
               
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              • Mopar Sam

                Mopar Sam Well Fed Member

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                If you look at the way the lifters are made, the lifter would hit the dogbone before the oil hole would be uncovered.

                So, as long as the maximum lift of the lobe does not cause the lifter to contact the dogbone, there will be no oil loss problems.
                 
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                • Mopar Sam

                  Mopar Sam Well Fed Member

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                  Here is the where the lifter would contact the dogbone. You can see that the oil hole would remain covered. Screenshot_20211125-085808_Firefox_LI.jpg
                   
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