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My apologies to everyone that used my information.

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  • My apologies to everyone that used my information.

    I want to apologize for any miss leading information I've said about the rocker arm ratios on the 1600 Road Stars.
    This last Friday I was fortunate to meet and talk with Nigel Patrick, owner of Patrick Racing. We had a good conversation through-out his shop and I found it very interesting and educational. While talking about differences with the 1600 and 1700s, he brought up something that I questioned. The stock 1600 rocker arm ratio vs. the 1700 ratio and how it effects the lifters and cams. I was always told, and I did ruff measurements myself, that the 1600 rockers had a ratio of 1.9 to 1. Nigel corrected me and said that the ratio is 1.6 to 1. There is still a difference, but not what I have been putting on this forum. I stand corrected, and hope that it hasn't messed anyone up with their engine builds. My apologies.

    If anyone has purchased the Speed Star heads, Nigel's shop did the work for Yamaha, along with a lot of other Speed Star components. He has help Harley Davision design the Milwaukee 8 heads and I found him very likable and knowledgeable while enjoying my visit with him and Jamie, his wife.

  • #2
    1.6 is more "car like" in terms of rocker ratio and easier to remember!
    LET'S RIDE

    Comment


    • Duke
      Duke commented
      Editing a comment
      Yeah, when I used to build the SB Chevys for dirt tracks, I would put the 1.5 on the intake, and the 1.6 on the exhaust, depending on the cam. Sometimes I would use the 1.6 only on the outer 4 cylinders.

  • #3
    I would have loved to have met him and Jamie and tour the shop. I have spoken to both a few time on the phone and they are very polite, professional and helpful when you talk to them. If he helped in the design of the M-8 heads that would explain the similarities to the Roadstar head.

    Comment


    • Duke
      Duke commented
      Editing a comment
      I know you would have enjoyed the visit Dave.

  • #4
    Remember we'd talked about going to heavier valve springs in regards to running 5k RPM with the Dyna 3000 on a 1600 to eliminate valve float? Would this make doing that more viable rather than less? Just curious.

    Comment


    • #5
      The 1600 has more load on the lifters-to-cam than does the 1700. Putting heavier valve springs on would increase the load on both 16 and 1700s. You can do it, just remember that your putting more loads on the lifters & cams.
      If you are not changing the cams, then I would stick with the stock springs.

      Comment


      • #6
        Spoke with Nigel at PR today about cams for a 1600 and confirmed above posts plus some other info. Actually first I spoke with shortblock Charlie who told me try Web-Cams for cams. Web cam said they used to stock cams for the 1600 and 1700 back when PR Racing was able to get ceramic surfaced lifters. They said to check with PR because they heard a rumor they might have gotten another ceramic lifter source. So I call PR racing and talked with Nigel who said they still do not have a source and that's why they stopped doing kits for the 1600 due to the 1.6:1 stress on the cam. Interestingly though he confessed they may have overstressed being on the safe side and the probability of cams getting eaten on the 1600 without ceramic lifters may have been less likely than originally thought, but qualified that by saying he wasn't confident enough to make cam kits readily available. Bottom line he would do a cam kit for me but it would be using non-ceramic lifters like the 1700 and the risk would be on me, but also said it just may hold up fine. Which leads me to thinking how much more load is actually on the 1600 cam over the 1700. Is it really enough to be a cam eating issue.

        Comment


        • #7
          I do not think so as long as the "lifter to cam" is getting plenty of good oil, lifter rotation, and mated surfaces break in together right. Most HP flat tappet cam manufacturers suggest to using weak valve springs to break-in the cam to lifters.

          Comment


          • #8
            I always thought the lifters were the same on both 1600 and 1700's?????

            Comment


            • davej
              davej commented
              Editing a comment
              PR lifters are ceramic coated. I have a set installed in my bike. I'm confused why they can sell 1700 cams with ceramic lifters but don't have the same lifters to sell for 1600 cams????

            • Duke
              Duke commented
              Editing a comment
              PR doesn't have the ceramic lifters on either bikes, they are the same lifter. I believe that when they sell a 1700 kit, they use a standard lifter. I know the Nigel wants the 1600 lifters to be the harder ceramic lifters due to the increased pressures from the rocker ratio difference.

            • davej
              davej commented
              Editing a comment
              I know back when I got mine he was having issues getting them in a timely manner. I waited an extra few weeks to get my parts back because of the lifters.

          • #9
            yes Dukes right. they don't have ceramic lifters for the 1600 at all right now and they didn't need them for the 1700 because the lighter lifter/cam load due to rocker ratio. sorry for any confusion there Dave.

            Comment


            • #10


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              • Duke
                Duke commented
                Editing a comment
                How old is that ad?

            • #11
              Originally posted by Duke View Post
              I want to apologize for any miss leading information I've said about the rocker arm ratios on the 1600 Road Stars.
              This last Friday I was fortunate to meet and talk with Nigel Patrick, owner of Patrick Racing. We had a good conversation through-out his shop and I found it very interesting and educational. While talking about differences with the 1600 and 1700s, he brought up something that I questioned. The stock 1600 rocker arm ratio vs. the 1700 ratio and how it effects the lifters and cams. I was always told, and I did ruff measurements myself, that the 1600 rockers had a ratio of 1.9 to 1. Nigel corrected me and said that the ratio is 1.6 to 1. There is still a difference, but not what I have been putting on this forum. I stand corrected, and hope that it hasn't messed anyone up with their engine builds. My apologies.

              If anyone has purchased the Speed Star heads, Nigel's shop did the work for Yamaha, along with a lot of other Speed Star components. He has help Harley Davision design the Milwaukee 8 heads and I found him very likable and knowledgeable while enjoying my visit with him and Jamie, his wife.
              I've spent a lot of time thinking about what Nigel had told me about the rocker ratio for the 1600s, and I think that maybe he was thinking of other bikes or other something. I've been doing the math on the 1600 and 1700 cam lifts to valve lifts, and the 1.6 rocker ratio doesn't add up. The best I can figure is the 1600 rocker arm ratio is 1.9 to 1. If it was 1.6, then the valves would only move .289" and when I checked the valve movement it was .344" lift. The 1600 OEM cams have a lift at 0.182" x 1.9 = 0.345",
              The 1700 has 1.4 rocker ratio and the lift on the cam is 0.244" lift. 0.244" x 1.4 = 0.342" valve lift.
              I will be checking the valve lift again on my next engine build to confirm this to be accurate.

              Comment

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