Flat Tapped Cam With Roller Rockers?

Discussion in '1965 - 1973 Classic Mustangs -General/Talk-' started by Braden65, Jul 19, 2014.

  1. We installed a mild cam and intake. Tried to reuse the original rocker arms only to realize they were shot. Bought some flat tappet rockers from the machine shop only to install them and have them break on installation. Machine shop guy sold us roller rockers instead. We didn't know any better. Cue now and studs are coming up. We've been told threading is the way to go but still trying to decide. And slight ring wear is visible on the pushrods. We've pinned one of the studs but that's a difficult process for 16 valves. Any suggestions? We've been told mixing roller with flat tappet is bad for the valve train. Should we go back to flat tappet or what?
  2. it sounds like the new cam has to much lift for the studs to handle. maybe machine the heads for screw down studs, or look into some lightly used heads that already have that feature.
  3. This is the cam sheet. It's a less than mild cam didn't think we'd run Into these problems. And whoever posted asking about lifters they are hydraulic liftersq but I was talking about the roller rockers mixing with the flat tappet cam. Iv heard that can cause problems. I'm considering biting the bullet and spending 1200 or so on heads. What would be good heads to mix with the cam? Are roller rockers okay with a flat tappet cam?

    Attached Files:

  4. There is no issue using roller rockers with a flat tappet cam, they don't touch each other. That cam is for 1962-1981 engines (and related spark control systems); is that what you're installing it in?
  5. Yes it is but we don't know what's causing the wear to the pushrods
  6. Its not bad, but there is a clear rimg where the pushrod is rubbing on the rocker arm. We kept the same pushrods that came with the flat tappet rocker arms. Could that be the problem? Pushrods not made for roller rockers?
  7. Whenever you make changes in the valve train you need to measure or at least check the push rod length. It is possible that the push rods are not the correct length for the application that you have. If you have any sort of binding in the valve train you will likely have problems with the studs as well. Check the push rod length first. Additional pictures of what you are describing may also be helpful.

    Unless you are looking to increase the performance of the engine then replacing the cylinder heads may not be warranted. As stated above, flat tappet cams and roller rockers are not an issue when used together.
  8. What 84Ttop said, no problem mixing flat tappet cams with roller rockers, but the roller rockers will change the geometry of your valve train, specifically your PR length. Summit sells an adjustable PR for checking length.

    As an aside, make sure you're using a ZDDP rich oil to protect your flat tappet cam. Shell's Rotella T is a common go-to.
  9. It's a freshly rebuilt 289.we are using a zinc additive. We were using straight 30 oriellys brand with a bottle of zinc, but now are going to use 5w-30 Quaker state with a bottle of zinc additive. It was the cheapest. Is that 5w-30acceptable? How do I know which pushrod length is acceptable with the aftermarket rocket arms?or does pushrod length rely entirely on the engine.
  10. Braden65 likes this.
  11. Thank you. Very informative
  12. <----another vote for pushrods
  13. as far as your oil goes, you will be fine but, why dont you just get some oil that has the zinc in it?
  14. if you used the old push rods, they were worn in to the old rockers. now you have them on new rockers, and the wear patterns are different.
  15. this would be sufficient? I wouldn't need an additional zinc additive?

    Attached Files:

  16. The pushrods never got used. When installing the new pushrods that came with the new flat tappet rockers, the rockers cracked on installation so we pulled them off and got roller rockers (using the same never used pushrods).
  17. Attached Files:

  18. So long as the adjustable push rod works within the range you need, any one will suffice. Check the length of the push rod you have now and order an adjustable one that is approx the same length. They make a few different lengths and obviously you wouldn't want it too short or too long.

    As far as oil goes, I prefer Brad Penn "Green Oil" you can learn more about that here: http://www.penngrade1.com/Default.aspx
    It may not be readily available everywhere unlike the Rotella and this may be the only draw back. I have been using this oil for almost 3 years now and have really had amazing results with bearing longevity and engine metal surface protection. We are super hard on our cars and my engine is apart multiple times a year for various issues and we have yet to have a scuffed bearing or a poorly lubricated surface. In years past we haven't enjoyed this same longevity while using the Rotella product. I'm probably an extreme case, but for what it's worth, Brad Penn is my only oil choice