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need valve lash advise if I don't know the cam

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  • Michael H.
    Expired
    • January 29, 2008
    • 7477

    #31
    Re: need valve lash advise if I don't know the cam

    Originally posted by Ian Gaston (47813)
    Hey Duke,

    I know you really like the LT1. Never having owned an old corvette, I really like the idea of having it the way it was in 1959...or as close as possible. Will the fuelie sound and drive the same with the LT1 cam in it?
    I have the engine almost completely disassembled to put on the correct heads and water pump, so putting a repop Duntov cam in it wouldn't be much trouble... I read the '097 has a very unique sound to it.

    thanks for your advice as always,
    ian
    If I were that close to the cam, and I wasn't sure which cam it is, I would definitely replace it with the correct 097. Or, at least remove it and find out exactly what it is.
    The 097 does have a unique sound that's part of old Corvettes.

    Comment

    • Stuart F.
      Expired
      • August 31, 1996
      • 4676

      #32
      Re: need valve lash advise if I don't know the cam

      .008" x .016" on a 097 cam idled @ 600 rpm will give you smoke rings out the pipes on a cold morning. Then you'll know you have it right.

      Stu Fox

      Comment

      • Duke W.
        Beyond Control Poster
        • January 1, 1993
        • 15610

        #33
        Re: need valve lash advise if I don't know the cam

        I don't buy this "unique sound" business. The idle characteristic is basically a function of overlap and both the Duntov and LT-1 cams have about the same effective overlap, so they exhibit the same basic idle characteristic.

        At the proper lash setting or a few thousandths looser, the Duntov will exhibit more valvetrain noise because is has much higher jerk and acceleration just above the tops of the clearance ramps than the LT-1 or 30-30 cams.

        Though I consider the LT-1 cam to be a much better grind for 327s with big port heads, it is not that well suited to a 283 with small port heads, which is the configuration that the Duntov was designed for, but it has too much overlap.

        The durations are good but the LSA is too narrow. If you want to spend an extra 100 bucks for better torque bandwidth, have Crane grind it to POMLs of 110/118 rather than the OE POMLs of 108.5/112.5.

        You didn't say anything about the heads, but having them pocket ported/port matched and relieving chamber overhang on the sides, particularly the exhaust is well worth the effort, and target a CR of 10.25:1. Use the 3911068 or equivalent (like Sealed Power VS677) valve springs, and I'd also recommend better con rods like the Eagle SIR, which are only about $250 a set.

        Mike Ernst lost a '57 FI a couple of years ago when a rod broke!

        Do all the above and the engine should have good low end torque, make useable power to 7000+, and be reliable as the Rock of Gilbrater.

        Duke

        Comment

        • Ian G.
          Extremely Frequent Poster
          • September 3, 2007
          • 1114

          #34
          Re: need valve lash advise if I don't know the cam

          Thanks very much for the advice. I've been toying with the idea of rebuilding the engine, because the CR is only about 8.6 right now due to low horse pistons in there... Just the insurance of having stronger rods in there seems like a good idea.

          When Mike had a rod go, it wasn't possible to have that cylinder resleeved? That really sucks.
          What is the likelihood of something like that happening? I don't plan to push the car very hard. I never redline my driver either.

          Comment

          • Joe C.
            Expired
            • August 31, 1999
            • 4598

            #35
            Re: need valve lash advise if I don't know the cam

            Originally posted by Duke Williams (22045)
            I don't buy this "unique sound" business. The idle characteristic is basically a function of overlap and both the Duntov and LT-1 cams have about the same effective overlap, so they exhibit the same basic idle characteristic.

            At the proper lash setting or a few thousandths looser, the Duntov will exhibit more valvetrain noise because is has much higher jerk and acceleration just above the tops of the clearance ramps than the LT-1 or 30-30 cams.

            Though I consider the LT-1 cam to be a much better grind for 327s with big port heads, it is not that well suited to a 283 with small port heads, which is the configuration that the Duntov was designed for, but it has too much overlap.

            The durations are good but the LSA is too narrow. If you want to spend an extra 100 bucks for better torque bandwidth, have Crane grind it to POMLs of 110/118 rather than the OE POMLs of 108.5/112.5.

            You didn't say anything about the heads, but having them pocket ported/port matched and relieving chamber overhang on the sides, particularly the exhaust is well worth the effort, and target a CR of 10.25:1. Use the 3911068 or equivalent (like Sealed Power VS677) valve springs, and I'd also recommend better con rods like the Eagle SIR, which are only about $250 a set.

            Mike Ernst lost a '57 FI a couple of years ago when a rod broke!

            Do all the above and the engine should have good low end torque, make useable power to 7000+, and be reliable as the Rock of Gilbrater.

            Duke

            As a supplement to Duke's always excellent advice, including his Rock of "Gilbrater" (Gibraltar) comments.

            Install the "30-30" cam custom ground by Crane on a 116 degree LSA instead of its original 114 degree LSA. Increase compression ratio accordingly to compensate for the later intake valve closing event @ 116 LSA, if installing at anything less than 6 degrees advanced. Install the cam 4 to 6 degrees advanced. The wider LSA and smaller resulting overlap will give a smoother idle and more idle vacuum, which will work better with your Rochester Fuel Injection. Set the valve lash at .027/.027, instead of .030/.030.

            This config will make * virtually the same peak power as the 30-30 cam, but with * virtually all of the additional bottom/midrange torque of the LT1. The wider LSA is better suited to the smaller displacement of the 283. Have your intake valves ground with 30 degree seats to maximize flow at low lifts, which will take advantage of your 1.94" intake valves.

            The downside to this, as opposed to installing a normally ground 30-30 (which is not advisable for a 283), is that the engine will lose some of that exciting "come on the cam" rush, which is a joy to experience with the 30-30 cam, but which is, unfortunately, lacking in the LT1.

            * within 1 per cent

            Comment

            • Michael H.
              Expired
              • January 29, 2008
              • 7477

              #36
              Re: need valve lash advise if I don't know the cam

              Originally posted by Ian Gaston (47813)
              Thanks very much for the advice.
              Well Ian, are ya thoroughly confused now? I sure am.

              Comment

              • Joe C.
                Expired
                • August 31, 1999
                • 4598

                #37
                Re: need valve lash advise if I don't know the cam

                Originally posted by Michael Hanson (4067)
                Well Ian, are ya thoroughly confused now? I sure am.
                Hey Michael............did ya just bail???
                Stay in fer the good part, will ya.

                Comment

                • Michael H.
                  Expired
                  • January 29, 2008
                  • 7477

                  #38
                  Re: need valve lash advise if I don't know the cam

                  Originally posted by Joe Ciaravino (32899)
                  Hey Michael............did ya just bail???
                  Stay in fer the good part, will ya.
                  Joe, I'm not confused by the numbers. I'm confused about where a discussion about the 30-30 cam came from.

                  I think Ian wanted to know how to tell if he has the correct 097 cam.

                  Does anyone happen to have the gross lift (at the cam) for that cam handy? He's using a dial indicator so it would be easier to provide total indicator movement rather than get involved in "checking clearances".

                  I have this info here somewhere but I'm not sure where.

                  Comment

                  • Ian G.
                    Extremely Frequent Poster
                    • September 3, 2007
                    • 1114

                    #39
                    Re: need valve lash advise if I don't know the cam

                    Hey Michael,

                    Using a bore dual indicator I came up with .32/.31 so I think the cam is an LT1. So then the conversation went to whether I should take the plunge and switch out what appears to be the LT1 cam and get the 097. I decided to get the 097 cam. Based on the discussion and previous threads, the LT1 will be fine, but I like the idea of using the 097 since some folks think it sounds better than the LT1, and well that's what was in it when it was built...

                    Urban legend? I dunno.

                    I don't think I would mess with any custom grinds of a 30-30 (bad for fuelie anyway right) or the '097, since honestly its out of my league and I don't want to screw it up. The only reason I'm even thinking of changing the cam, is because I have the heads off and need to cange out the water pump and motor mount anyway. So that leaves very little work to do to put in the "correct" cam... But now I'm wondering again if I just go all the way and have the engine rebuilt, since the pistons are low horse kind with indents and the CR as I calculated it is only 8.6 when it should be 10.5 per GM (maybe 10.0 in reality?).

                    Comment

                    • Joe C.
                      Expired
                      • August 31, 1999
                      • 4598

                      #40
                      Re: need valve lash advise if I don't know the cam

                      Originally posted by Michael Hanson (4067)
                      Joe, I'm not confused by the numbers. I'm confused about where a discussion about the 30-30 cam came from.

                      I think Ian wanted to know how to tell if he has the correct 097 cam.

                      Does anyone happen to have the gross lift (at the cam) for that cam handy? He's using a dial indicator so it would be easier to provide total indicator movement rather than get involved in "checking clearances".

                      I have this info here somewhere but I'm not sure where.
                      A conversation Duke and I had recently, where I demonstrated the benefits of widening the LSA on the 30-30. Have shown that doing so reaps all of the best qualities of both the LT1 and the 30-30, with no givebacks (except the exhilarating "come-on-the-cam" rush delivered by the 30-30 @ about 3500.)

                      On January second, Ian seems to have deduced that he may have an LT 1 cam installed, based on the accuracy of his measurements, but that conversation was in a far off galaxy........................... a long, long time ago.

                      Since then we have discussed the finer points of geometry, error factors, included angles, dial indicators, bore dial indicators, cam identifier location(s), LT1 universal replacement cams, and Einstein's Theory of Relativity. Since the 30-30 cam ground on 116 LSA outperforms both the LT1 and the original 30-30, it was worthy of insertion into this rather far ranging discussion.

                      Hey................I just had a great idea.............why not have a few members donate their engines as "Special 30-30 Cam" test mules?

                      LT1 lobe lifts: .3057/.3234

                      The 097 is Sealed Power CS113R: LL .2633/.2673

                      Comment

                      • Michael H.
                        Expired
                        • January 29, 2008
                        • 7477

                        #41
                        Re: need valve lash advise if I don't know the cam

                        Originally posted by Joe Ciaravino (32899)
                        The 097 is Sealed Power CS113R: LL .2633/.2673
                        Thanks Joe. That's what I was after.

                        Comment

                        • Duke W.
                          Beyond Control Poster
                          • January 1, 1993
                          • 15610

                          #42
                          Re: need valve lash advise if I don't know the cam

                          Originally posted by Joe Ciaravino (32899)
                          Have shown that doing so reaps all of the best qualities of both the LT1 and the 30-30, with no givebacks (except the exhilarating "come-on-the-cam" rush delivered by the 30-30 @ about 3500.)
                          It comes "on the cam" because it doesn't have any friggin' torque below 3500. The LT-1 cam doesn't have the huge 30-30 hole in the torque curve below 3500, and they both make about the same top end power, all other things equal.

                          Which one do you think will make the best performing road engine?

                          Autocross?

                          Drag race?

                          Track hot laps?

                          You're putting waaaaaaaaaaaaaay too much faith in EA. You can't split the hairs that fine.

                          The OE spec gross lobe lift of the Duntov Cam is .2625/.2665.

                          Duke

                          Comment

                          • Joe C.
                            Expired
                            • August 31, 1999
                            • 4598

                            #43
                            Re: need valve lash advise if I don't know the cam

                            Originally posted by Duke Williams (22045)
                            It comes "on the cam" because it doesn't have any friggin' torque below 3500. The LT-1 cam doesn't have the huge 30-30 hole in the torque curve below 3500, and they both make about the same top end power, all other things equal.

                            Which one do you think will make the best performing road engine?

                            Autocross?

                            Drag race?

                            Track hot laps?

                            You're putting waaaaaaaaaaaaaay too much faith in EA. You can't split the hairs that fine.

                            The OE spec gross lobe lift of the Duntov Cam is .2625/.2665.

                            Duke
                            Calm down.......take it easy, Duke, my friend.

                            You are correct (although given to some hyperbole) in your characterization of the "come-on-the-cam" feeling, and the lack of it with the LT1! In point of fact, the LT1 equipped 327 shows about 6 per cent more torque than the 30-30 @ 2000RPM, which decreases to zero by 4250, at which point, the 30-30 takes over.

                            Perception is the greater part of reality.

                            The 30-30 with its slight deficit in low end torque, actually FEELS stronger, and more exhilarating than the more streetable, docile, and bland LT1.

                            An analagous situation might be why one would rather drive his 1965 fuel coupe rather than his 2008 ZR1 with all the comforts of home.

                            In a DRAG RACE between two identically equipped and geared 327 powered (NOT a 327 with 30-30 and 350 with LT1) Corvettes, one with the 30-30 and the other with the LT1. The LT1 equipped Corvette would probably be very slightly quicker, but the 30-30 equipped Corvette would be faster.

                            LL specs, talk about splitting hairs....................

                            Comment

                            • Joe C.
                              Expired
                              • August 31, 1999
                              • 4598

                              #44
                              Re: need valve lash advise if I don't know the cam

                              I found an error in my post of 1/4/09, 13:29 and corrected it, in an ongoing effort to prevent the dissemination of faulty information:

                              Install the "30-30" cam custom ground by Crane on a 116 degree LSA instead of its original 114 degree LSA. Increase compression ratio accordingly to compensate for the earlier intake valve closing event @ 116 LSA. Install the cam 4 to 6 degrees advanced. The wider LSA and smaller resulting overlap will give a smoother idle and more idle vacuum, which will work better with your Rochester Fuel Injection. Set the valve lash at .027/.027, instead of .030/.030.

                              Now reads:

                              Install the "30-30" cam custom ground by Crane on a 116 degree LSA instead of its original 114 degree LSA. Increase compression ratio accordingly to compensate for the later intake valve closing event @ 116 LSA, if installing at anything less than 6 degrees advanced. Install the cam 4 to 6 degrees advanced. The wider LSA and smaller resulting overlap will give a smoother idle and more idle vacuum, which will work better with your Rochester Fuel Injection. Set the valve lash at .027/.027, instead of .030/.030.

                              Comment

                              • Duke W.
                                Beyond Control Poster
                                • January 1, 1993
                                • 15610

                                #45
                                Re: need valve lash advise if I don't know the cam

                                Advanced from WHAT? "Advance" or "Retard" has to be relative to some datum.

                                So...?

                                Duke

                                P.S. Your best move to be to remove all this "advance" and "retard" hot rod gobbledygook (which is, unfortunately part of the Engine Analyzer program) from your vernacular and start talking in terms or POMLs.

                                When you go to get a cam ground you better tell them the exact POMLs you want. Otherwise you may not even know how the cam is indexed, or they will pick whatever indexing they think is "right".

                                Comment

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