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question on hydraulic lifters |
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Ken_Parkman
AMC Addicted Joined: Jun/04/2009 Location: Ontario Status: Offline Points: 1815 |
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If you are just cruising it does not matter. Just crank it down a turn or so, then forget it. The .002-.004 is for the racers using hydraulics for when you loose control of the valvetrain and it can't pump up with that preload. Personally I think it a bad idea - I've had the clips break. If you run it that hard as you say run a solid. For a hydraulic set it once, forget it, and stay out of valve float.
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WesternRed
AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5787 |
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I have heard that also Ken Parkman, some people like to run very little preload on hydraulic lifters because it means they cannot pump up very far if at all.
Solid lifters are very different to hydraulics, from my understanding solid lifter lash is normally set hot, hydraulics have some leeway because of the nature of the lifter so it is probably not as critical what the actual amount of preload is, provided it is within the working range of the lifter. Remember that one of the advantages of the hydraulic lifters from the engine manufacturer's perspective is that they do not require any provision for adjustment on the assembly line. For a hobby car the need to periodically adjust solid lifters is hardly a problem, might be different if you were doing +20,000 miles per year. |
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ScrambledEgg
AMC Nut Joined: Nov/24/2007 Location: Upstate NY Status: Offline Points: 348 |
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Thanks for the replys Ken and Western. I agree with your thoughts.
Here are a few more tidbits from what I was able to garner after pouring over the internet: Within the Comp Cams line, there are four families of hydraulic flat tappet lifters and they all have their specs for preload based on what they were each designed for: High Energy - basic lifter Pro-Magnum - anti pump up lifter for street and extended periods of use. Hi-Tech - Not for street cars as they cannot be used for extended periods of time continuously. Made for class racing where you must run hydraulic and meet a certain amount of vacuum to participate in the class. Race - Not for street cars. Made to high tolerance/strict standards, heavy duty snap ring. Ford and Chevy availability only. http://www.compcams.com/Products/CC-%27Hydraulic%20Lifters%27-0.aspx The Pro-Magnums are to be set with .002-.004 preload as they want the minimum preload (almost zero lash) to prevent the lifter from pumping up at high RPM. This allows them to mimic the properties of a solid lifter within a hydraulic line. The trade off is that its gonna be noisy. I can attest that they are noisier than a solid lifter. Can I put more preload on them to make the noise go away - yes, but it defeats the purpose of what this specific lifter was designed for. At the end of the day, at least I know I was setting the pre-load per manufacturer spec and understand why I have valve train noise. I also have learned that I will never buy another hydraulic lifter cam again. They are way to wishey washey for me. No benefit and all downside. I would rate hydraulic lifters as the lifter of choice for a house wife's car. Not my taste at all. This is my first and last hydraulic cam. If I ever tear it down, the cam and lifters will be removed and tossed in the trash where they belong. If I ever go roller, it will NOT be a hydraulic roller. That is for sure. Thanks again to everyone's responses. It was very helpful and I certainly do appreciate and respect each of your input. Mark |
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ScrambledEgg
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6PakBee
Supporter of TheAMCForum Charter Member Joined: Jul/01/2007 Location: North Dakota Status: Offline Points: 5454 |
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I wouldn't be so hasty in that conclusion. For a street engine under 6,000 rpm with reasonable valve springs I'll take a hydraulic any day. Easier on valve components and more trouble free (usually) than solids. I'm getting to the age where I enjoy driving them more than working on them. As a note, the best thing that ever happened to the 2nd generation Mopar Hemi was hydraulic lifters. Setting the solid lifters on a Hemi is defined by some as cruel and unusual punishment. That's why a lot of Hemis got waxed back in the day as that engine is very sensitive to valve lash and it was too much of a pain for some owners to do regularly. |
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Roger Gazur
1969 'B' Scheme SC/Rambler 1970 RWB 4-spd Machine 1970 Sonic Silver auto AMX All project cars. Forum Cockroach |
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Ken_Parkman
AMC Addicted Joined: Jun/04/2009 Location: Ontario Status: Offline Points: 1815 |
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Yes, a hydraulic in the right application is an excellent thing. Just keep the rpm band in an acceptable range and don't over do the duration and they are excellent.
As a general rule below 5500 rpm a hydraulic is almost a no brainer. In different situations you can start to have lifter problems approaching 6000 rpm, but if you do the right things they can be rpmed higher. But above 6000 is where solid's make a lot more sense. I have a hyd roller in my street car and it make excellent power, with a good power band to 6500. There was a little effort in the valvetrain to do that.
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ScrambledEgg
AMC Nut Joined: Nov/24/2007 Location: Upstate NY Status: Offline Points: 348 |
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To each their own. Hydro is not at all for me. I have never had a single failure or issue with any solid lifter in my lifetime and I have rung them out beyond what I would consider extreme. Measuring lash and making the adjustment when needed is simple and exacting - no guess work or estimating. I am way to much of an exacting tolerance person with the go or no-go type of thinking (previously in the aerospace industry where nothing is 'in the breeze','close enough' - or 'forgiving'). In the end, its all good and everyone has their own opinion and choice. |
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ScrambledEgg
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73hornut
AMC Addicted Joined: Jul/03/2007 Location: Southern Oregon Status: Online Points: 3132 |
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try a 7.095 push rod.
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71 Javelin
74 Gremlin 79 Spirit AMX Rogue Valley Rumblers Like Us on FB https://www.facebook.com/groups/1602825606650796 |
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6PakBee
Supporter of TheAMCForum Charter Member Joined: Jul/01/2007 Location: North Dakota Status: Offline Points: 5454 |
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Roger Gazur
1969 'B' Scheme SC/Rambler 1970 RWB 4-spd Machine 1970 Sonic Silver auto AMX All project cars. Forum Cockroach |
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uncljohn
AMC Addicted Joined: Jan/03/2013 Location: Peoria AZ Status: Offline Points: 5394 |
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I too have been in aero-space where it is a critical go or no-go agenda, primarily based on the inability to service something that is approaching the concept of light years or so away when it breaks or some equally foolish distance.
Parts have applications and when you select what is needed as an objective for an application you select what works the best. I too have had a couple of solid lifter engines, but they like my hydraulic lifter engines were built for the street and lash numbers were selected to get reliable service for the intended objectives that they were built for. And setting things a tad loose with the trade off being a bit of lifter noise to tolerate while gaining extended time between service intervals which on a street motor with A/C, power steering and brakes and a number of other doo-dads that make driving something comfortable and easier to take care of are an objective along with improved performance. Solids were o.k., and they worked, but I'll take hydraulics in a New York minute as an alternative. When used as they were intended to be used and for what they are intended to be used for, they have work well for me. Of course selecting parts to be used for an objective that they had no reason to be used for is a recipe for nightmarish experiences. |
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70 390 5spd Donohue
74 Hornet In restoration 76 Hornet, 5.7L Mercury Marine Power 80 Fuel Injected I6 Spirit 74 232 I-6, 4bbl, 270HL Isky Cam |
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Traveller
AMC Addicted Joined: Feb/26/2011 Location: Idaho Status: Offline Points: 1011 |
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I'm not a fan of high bleed lifters, since you're defeating the purpose of the hydraulic to a degree, to try to extend the top end and pick up a little bottom end by reducing duration at low RPM. Picking a better set of matched components designed for your use is the better way to go in my opinion. If you run spring pressures that are correct for your intended use, running a good quality lifter will keep them from pumping up anyway, as you won't get into valve float. If you stay out of valve float, the lifters won't pump up past zero lash, as they won't have any room to.
And yes, the adjuster at the pushrod sets lash directly, while adjusting at the fulcrum has a different effect. I was being a bit simplistic. Still, half a turn of preload at .025 of fulcrum movement, will only yield ~.040 or so at the lifter, which is why 1/2 a turn is good street adjustment. I do 1/4 turn for street strip stuff and run a valvespring that keeps it out of float for the RPM range I'm running. |
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