Difference between hyd flat tappet and hyd roller cam?

Discussion in 'Mopar Performance Issues' started by LovetheA's, Oct 2, 2018.

  1. LovetheA's

    LovetheA's FABO Gold Member FABO Gold Member

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    I’m asking this question because I often get confused as I’m attempting to fix/upgrade/repair my 67 Dart. Currently I’m installing a new timing set and chain due to chain slack/wear. I noticed in the Cloyes timing gear set I ordered there was a three bolt cam gear and a cam thrust bearing. The problem was that my original mopar performance cam in my 383 is a one bolt cam. Therefore I couldn’t use my three bolt Cloyes cam gear. No problem I inspected my single bolt cam gear teeth look good and it measure out at the same exact size as my three bolt. I’ll just put it back in instead. Then I couldn’t figure out where to put the cam thrust bearing included in the kit? I didn’t remember seeing one when I pulled off the lower crank gear? After reading a bit I think I know why. With traditional flat tappet hydraulic cams based on the lobes and the clockwise revolution of the cam it doesn’t want to walk forward but instead move back. Therefore a cam thrust bearing isn’t needed as well as a cam button for the timing cover. Only when you move to a hyd roller are those things needed because the cam can walk forward. Do I have it correct everyone?
    Carl

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  2. pishta

    pishta I know I'm right....

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    Correct, the roller lobes are perfectly parallel with the axis of the cam so there is only the distributor/oil pump rotation that will push on the cam toward the rear of the block. A thrust button is usually employed to butt against the timing chain cover. you can get roller thrust buttons too. Notice thrust button buttress plate

     
    Last edited: Oct 2, 2018
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    • LovetheA's

      LovetheA's FABO Gold Member FABO Gold Member

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      Thanks pishta I’m starting to get it.
       
    • dartgarth

      dartgarth Well-Known Member

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      The Torrington thrust bearing in your kit is just there so the cam gear doesn't just ride on the block. On a flat tappet cam with the way it's ground, the lifter rotation "locates" the cam and it doesn't walk back and fourth. With a roller cam it can walk either way, the cam gear keeps it from going back but a cam button is needed to keep it from moving forward. There is a spec for the allowable amount of thrust movement on a roller cam.

      I used a really nice trick aluminum cover that my friend makes that makes setting the thrust super easy without taking the cover on and off multiple times...

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      • LovetheA's

        LovetheA's FABO Gold Member FABO Gold Member

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        Dartgarth
        That is a great idea for a timing cover. Are they for sale? How much? Fit B or RB engine with no mods?
         
      • Michael Harrington

        Michael Harrington Active Member

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        I want and plan to include a switch to a hyd roller in a 360 build. Total cost from hyd flat to hyd roller will exceed $1300 for everything.
         
      • dartgarth

        dartgarth Well-Known Member

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        Yes he makes them and sells them. They fit B or RB Blocks with no modifications and fit behind the stock timing cover, the only thing that doesn't fit is the oil slinger on the front of the crank (don't really need it anyway). You would also have to buy or make a timing pointer. There is one that fits I'm not sure which it is, I just made one from a piece of wire as I only need to know where 0 is because I use an advanceable timing light.

        He wants $280 CAN for them or about $220 USD.

        Garth
         
      • dartgarth

        dartgarth Well-Known Member

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        Oh he has them anodized in black too.

        He also makes a very nice valve cover......


        Garth