Still confused about adjusting hydraulic lifters.. - NCRS Discussion Boards

Still confused about adjusting hydraulic lifters..

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  • Terry F.
    Expired
    • September 30, 1992
    • 2061

    #16
    Re: Still confused about adjusting hydraulic lifte

    So, an engine that is only going to see a couple hundred miles a year can handle less pre-load on the lifter and it may be safer and develope more top end power?? Thanks for you input, Terry

    Comment

    • Mike McKown

      #17
      Re: Still confused about adjusting hydraulic lifte

      I'm thinking your expectations may be a little higher than the results you'll achieve. I believe if your engine is stock and in good condition, it'll rev past the point of peak power before valve float. Thus, no gain except more noise. I'd set the lifters by the book and be happy if it were mine.

      Comment

      • Dave Suesz

        #18
        Don't overthink this...

        "I am wondering about the technique of using a standard lifter and adjusting it to just when the play comes out of the rocker (I could totally be misunderstanding this method). My understanding is that it assumes the lifter will completely pump up at high RPM and act essentially as a solid?? I have talked to some people and they seemed to have never heard of such a technique? I also seem to recall reading something about this in my overhaul manual?"

        If you are not looking for normal operation above 5500 rpm, all you need to do is adjust each rocker to zero lash on the base circle, check by looking for axial play (up and down) movement of the pushrod, many people spin the pushrod but this is a mistake, as it is often possible to spin the rod even after the lifter plunger begins to depress. The tighten the retaining nut 3/4 turn. The lifters will not, unless they are defective, "pump up" when run at 5500 rpm, it would likely take 1000 rpm more than that. Even then, unless you were slamming the throttle wide open with the trans in neutral, what you would get is the valves gradually failing to seat, which would cause power loss, limiting your rpm. I knew a fella who was told he needed to "floor it" once in a while, to clear out the engine. One day he tried this in his 327 RS Camaro in the driveway, in park. After hitting maybe 7000 rpm, the engine shut down. No permanent damage resulted.

        About those roller rockers: The #137 car in the photo below had a race-prepared 327 Corvette engine (with dual-quads installed), and was built before availability of roller rockers. Jack used stock stamped steel rockers, which were case-hardened and tempered (Jack is a metallurgist). His redline was 8500 rpm under power, and could downshift/decelerate up to 10,500 rpm without damage. The worst he ever experienced with this engine was breaking the tip off one rocker. The last I heard the car still exists, and was being raced on the vintage circuit. Sadly, that owner destroyed the 327 engine, and has installed a more "modern" 350, with less power, than the 327, and has also had an upholstered interior installed, adding weight. In the form shown in the photo, Jack was clocked at over 200 mph at Riverside. Not bad for a car Jack built in his garage.




        Pomona
        Attached Files

        Comment

        • Mark #28455

          #19
          GET REAL!

          All this talk about "zero lashing" the lifters is a GIANT BAND AID to make up for inadequate valve spring pressure for a given RPM range. If you have the correct valve springs for your application and you keep the engine in the correct RPM range, the lifters will not suddenly "pump up". Lifters only pump up when the RPM goes high enough for valve float and the lifters take up the slack.

          I have done a LOT of stupid things with BB engines over the past 20+ years, but I have always followed the cam manufacturer's recs regarding valve spring specs and valvetrain limiting speed. By doing that, I have never had a case of the DREADED lifter pump up. The stock 390 HP cam will run perfectly with the stock valve springs for that cam up to 5600 RPM. If you're a little worried, you can swap the stock L88 springs (about 125# seat pressure), and stay out of valve float to over 6500 RPM, but there is a slight increase in valvetrain wear with the "stiffer" springs. Contrary to popular belief, the wear is not that much. I am running valve springs with 135 - 140# seat pressure and about 330# at max lift up to 7000 RPM. You certainly DO NOT need that stiff of a spring for the stock cam. With the correct springs, you should just use the factory specs for cam adjustment and forget about it for the next 50,000 miles or so!

          Mark

          Comment

          • A L.
            Expired
            • January 1, 1992
            • 63

            #20
            Re: Don't overthink this...

            Terry, while admitting I am no authority on this, I was around back in the sixties when we bought performance cars to run. It was pretty much accepted that the GM hydraulic lifers were safe to 6000 RPM and that lifter pump-up and valve float could/would occur thereafter. This is supported by the GM redline on the 327-350 HP engines(6000 RPM) which used pretty much the same lifter as the 390 HP-427. As a matter of fact, my parts book indicates it is the same lifter used in the 1966 390 HP. I have a 400hp 69 and have/had some thoughts also about wanting a 6000 RPM performer, but always realized that the 327-350 HP had forged steel crank, forged pistons, and high performance rods, and less rotating mass. The solid lifter 427's built to operate in the 6000 plus rpm range have all the forged stuff plus 4 bolt mains to deal with the rotating mass. The red line on my 400 hp is around 5600 rpm. It also has 2 bolt mains, a cast iron crank, and cast pistons. It is my opinion that GM did not set the 5600 RPM redline because of lifter pump up, but more so because of the bottom end. My point is that the normal prescribed GM method for setting hydraulics would not keep my 400 HP from safely turning 6000 RPM but there are other bottom end issues that would. Thanks for asking the question.
            AG

            Comment

            • Terry F.
              Expired
              • September 30, 1992
              • 2061

              #21
              Re: Still confused about adjusting hydraulic lifte

              I believe you are right. I was looking at my 68 overhaul manual and it stated one turn past zero lash. Do you know if chevrolet ever amended this to 1/2 or 3/4 turn past zero lash. I seem to recall reading something about this or reading other manuals and having them state something different. Can you recommend a manufacture of a good quality hydraulic lifter or single piece push rod? Thanks, Terry

              Comment

              • Terry F.
                Expired
                • September 30, 1992
                • 2061

                #22
                Re: Don't overthink this...

                I totally agree with you on the rocker arm business. There are a lot of things out there sold on hype. A stock rocker is simple and reliable and light weight compared to alternatives. Several things came into play when I decided to used full roler rockers. 1) I think the technology and engineering has made it possible for them to be reliable for the long run in a stock 390hp valve train. They have also made it over into standard production on modern engines. 2) As long as they are compareable in weight to stock rockers, they should perform as good or better than stock application in my near worthless opinion. My gut feeling is that they reduce the initial opening force required to open a valve at lower RPM's and this effect probably somewhat disappears at higher RPM's (just a guess). 3) I hate lateral guide wear and they will help prevent it in my opinion. 4) They produce less heat and need less oil which to some extent hints at their superiority if made with quality parts. 5) They are more uniformly made compared to stock rockers. 6) Lastly, because of all this they increase HP and torque over conventional rockers depending on the situation. I may be miss-informed on some of this but to some degree I believe most of it is somewhat correct.

                I love the example you gave that illustrated the capablility of standard rockers. It speaks directly to the KISS priciple and validates it whole heartedly. Keep it simple Stupid is usually where it is at for me.

                Thank you for your input. Best regards, Terry

                Comment

                • Terry F.
                  Expired
                  • September 30, 1992
                  • 2061

                  #23
                  Re: Don't overthink this...

                  Thanks for the well thought out responce. Exactly the reasoning I am looking for. It seems that for my purposes, if my valve train is put together properly, I won't be near the envelope where bad things happen to nice engines. Thanks, Terry

                  Comment

                  • Terry F.
                    Expired
                    • September 30, 1992
                    • 2061

                    #24
                    Re: GET REAL!

                    You are right. I am learning very quickly from all these responces. I am not too interested in increasing valve spring pressure. I can see maybe doing it slightly with the hope that it will be off set by the full roler rockers. Thanks, Terry

                    Comment

                    • Chris Patrick

                      #25
                      Re: GET REAL! - Is Mark the only sane one?

                      You guys are making far too much out of this. Like someone said, 6000 rpm is no big deal. You have lived around the C4 L98 engines too long.

                      Take a valve cover off, cut a piece of cardboard 8 to 10 inches high to wrap around the valves, so it looks like the end and bottom walls of a valve cover.

                      Fire up the engine, loosen a rocker until it clicks. Wait 30 seconds or so. Tighten until the clicking stops. Wait 30 seconds or so. Readjust if needed. Wait 30 seconds or so. Then turn it in 1/2 to 1 turn, depending on what you feel comfortable with. Wait 30 seconds or so. See if the engine idle is still normal.

                      Repeat this for all the others. Shut off the engine. Repeat on the other side.

                      In over 30 years of running and adjusting SBC and BBC, I have had two engines with incidents. One was a big block shortly after I got it, of questionable history, that shoved a pushrod through a rocker. The other was a 350 that began breaking rockers after a cam change. I didn't notice that the original rockers had some long slot and some short slot rockers in the mix, and apparently, there was just enough change in lift to hit with the short slot.

                      Almost all I have run to 6000 rpm, unless they were a doggy cam. Some I have turned 6500 with. None died except for the above two. And I never babied those engines.

                      Heck, most 18 year olds reading a Motors or Chilton's (or even a Hot Rod) can figure it out, so I would hope in your many extra years of experience on this planet you had learned to read enough to read the manual.

                      Comment

                      • Chris Patrick

                        #26
                        Re: Don't overthink this...

                        They cost a lot more than a stock rocker. If they didn't, then you probably have a street design or a cheap knock off that will come apart 10,000 miles from now.

                        Millions of miles have been driven on stock Chevy rockers. Heck, BILLIONS of miles. Most vehicles I have had for long driving have turned the clock a couple of times, all on stock rockers.

                        If you are racing, that is one thing. If not, it is a waste of money.

                        Comment

                        • Clem Z.
                          Expired
                          • January 1, 2006
                          • 9427

                          #27
                          just be carefull when changing rocker arms

                          because on some stock cams if you change the ratio to get higher lift you will also get premature valve float as much as 500 to 1000 RPMs. found this in dyno tests

                          Comment

                          • Terry F.
                            Expired
                            • September 30, 1992
                            • 2061

                            #28
                            Re: just be carefull when changing rocker arms

                            I will use a stock ratio. Who's lifters and push rods do you use? Thanks, Terry

                            Comment

                            • Dave Suesz

                              #29
                              I wasn't kidding about the rpm on

                              the DeMar Special. 8500-10500 with case-hardened heat treated stock Chevy rockers. Jack is still around, doing high-end metalwork with his own small company.

                              Comment

                              • Terry F.
                                Expired
                                • September 30, 1992
                                • 2061

                                #30
                                Re: just be carefull when changing rocker arms

                                I think I got started on this conversation by trying to get the most out of my valve train without venturing too far from the stock configuration. Thanks, Terry

                                Comment

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