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Old 12-02-2014, 02:13 AM
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Originally Posted by MER Performance
Mike,
I have looked at a couple of the past ; post in this "thread". Talking about needle bearings falling out, the only times needle bearings fall out is from bouncing the lifter, lifter hours beyond service. I have seen; hydraulic roller lifters drop the bearings out at removal. Spring pressures are limited on hydraulic roller lifters, and you can push their limits with spring pressure, RPMs, valve, retainer weight and lobe design.
You are certainly correct Mark in that generally something else is going on to cause a lifter to spit the needles out. However, it happens. Guys neglect to lash the valves, run them for longer intervals than they should, let springs get weak, improper geometry, etc. It can happen as well with a hyd roller, but I would say that it is more likely to happen (or should I say that it's easier to occur since the valvetrain is more "extreme") with a solid. The springs are stiffer, therefore, have more weight to lose. A 10% decrease in weight in an 800# spring is twice as much as a 10% drop in a 400# spring. A solid generally turns more rpm, the cams are generally more aggresive, etc. It's not neccessarily the fault of the lifters, it's just that things can go wrong with a solid a little faster and/or easier.

Not trying to argue with you. Just clarifying why I posted what I did earlier (3 yrs ago) in this thread.

Hope you are doing well. Haven't heard from you in a while. Need to catch up sometime.
Eddie
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Old 12-02-2014, 02:26 AM
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Originally Posted by HaxbySpeed
I run the 904's with no lifter bushings either. A good quality rev kit isn't a bad idea, but a nice tight lash solid deal, with bushed axle lifters can be incredibly reliable too. Anybody who is truly making 1200hp+ with a hydraulic roller is leaving lots of power on the table.. Opening the exhaust valve against all that pressure is a biatch.
You are right about leaving some power on the table. The issue is that most guys don't have the ability, tools, desire or know how to lash valves. Very few of my engines stay local. The majority of them go over 8 hours away. So, it's not really feasible for them to come back to me to have the lash done. They may or may not have someone near them that they trust or want to work on their stuff.

I talk about it with several of my customers, I would say that 99.9% of them do not want the hassle of a solid. They would rather sacrifice a small amount of power for reduced maintenance and the longevity. Obviously, there are some instances where you have to go to a solid. Since we only build marine engines, and pretty much all of those are pleasure boats, we have very little calling for solids. However, we do build a few. We currently have a few hyd rollers that we are turning close to 7000 rpm. So far, no issues with that rpm.

Hope you are doing well and staying busy.
Eddie
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Old 12-02-2014, 09:04 AM
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I agree hydraulics are a low maintenance alternative, but a good shaft rocker system all but eliminates having to set lash once it's done the first time. RPM isn't an issue if you have light enough valves, retainers, locks. But when controlling a heavy BBC marine valvetrain, the spring pressure required, combined with an aggressive cam, can certainly wreak havoc on the plungers. Based on my own personal testing, I have found the limit of the hydraulics to be more related to HP then RPM, also lobe profile plays a large factor. There are so many variables, it would take forever to type all the scenarios and factors at play, but in brief; as the lifter is coming up to open the exhaust valve at blowdown on a boosted engine, that particular part of the lobe is trying to snap the valve open very quickly against significant cylinder pressure, and valve spring pressure. This can cause the plunger to drop down in the lifter, destabilizing the valve and pushrod, and moving your exhaust opening point to where it shouldn't be. Best case scenario it acts like a rev limiter, and you have an engine that just won't pull to where peak HP should be, boost usually increases, the engine becomes more timing sensitive, and egt's go up. Worse case you break the plunger (I almost always break the freakin plunger). This phenomena, I was surprised to find out, doesn't just occur at high rpm. When upgrading to the high RPM Morel's in one engine, I found a 30hp gain as low as 3500rpm on a 1000hp 557. If you're going to run a hydraulic, run the best lifter you can get. Other benefits of a solid are, a lighter lifter, and because you don't need room for the plunger, you can get the pushrod right down close to the wheel, this of course greatly reduces side loading on the lifter, and you can run whatever spring pressure you need to control the valves. Hydraulics certainly have there place, but don't think the engineers at Merc were putting solids in just for the hell of it..
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Old 12-02-2014, 09:28 AM
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Originally Posted by HaxbySpeed
I run the 904's with no lifter bushings either. A good quality rev kit isn't a bad idea, but a nice tight lash solid deal, with bushed axle lifters can be incredibly reliable too. Anybody who is truly making 1200hp+ with a hydraulic roller is leaving lots of power on the table.. Opening the exhaust valve against all that pressure is a biatch.
while i agree that more power could be found with solids,in my application the gain is not worth the hassle of removing the center headers to gain access to the valve covers.you can barely slide a sheet of paper in there.
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Old 12-02-2014, 09:52 AM
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Good info, thanks guys.
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Old 12-02-2014, 11:33 AM
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If your valve train is stable, to begin with it; will not require constant adjustment. I have customers that run all season long, without adjustment, we usually check valve lash at the end of the season along with spring pressures and a visual. After the first; adjustment after break-in on the dyno and double checking after the dyno pulls are completed, the valve train is pretty much set.
If you have to continuously adjust valve lash, you better check push rod wall thickness, spring rates and use a shaft mounted rocker arm or add some stud girdles, that support the rocker arms properly.
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Old 12-02-2014, 03:34 PM
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I like that isky lifter design with bushings instead of needles. I worked in common rail pump design for a long time and we never even consider needle bearings in our lifters.
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Old 12-02-2014, 04:50 PM
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You guys bring up some great points. Another benefit of the solid roller, is if the lash IS out of spec, it may help track down a problem before it gets ugly.

With that being said, I can understand why certain guys do not want to mess with solids. Lots of boats, including mine, with the stellings headers, are a biotch to get the valve covers off, and alot of bilges are extremely tight. Some bilges you cant even get into, like my old Formula. Everything I did I had to do leaning on my chest or bent like a monkey. Pulling the valve covers and running thru all the valves at the end of every season, could get tiresome. For me, being kind of a gear head kinda guy, the solid rollers do spark my interest. I've got alot of buddy's though, who want the power, the sound, the speed, but don't even wanna change their own spark plugs, let alone run thru the valves. I know that with the right setup, good components, lash shouldnt change. But you still gotta check it. Getting to that point may be the hard part.

Great info guys.
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Old 12-02-2014, 05:39 PM
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MT- I'm leery of opening up my boat engine for more advanced preventive maintenance. Oil changes are no prob, but I don't have a local mentor to help me avoid the pitfalls. Couple that with the short boating season and a hydraulic cam is a no brainer.

That's one of the reason I appreciate these threads so much, the banter brings those nuances to light.
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Old 12-02-2014, 05:58 PM
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You probably do, but... Like me you have to figure out who they are.
So far for me the only one I know to trust is haxby 6 hours away.
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