Lifter Preload
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It's not just a matter of noise....it's also a matter of obtaining the most valve lift. Noise means (as I understand it) that your lifters are bottoming out, which means that valve lift is suffering. Personally, I want to know that the cam is able to do it's job just as it was intended.
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Imo it would hold the valve off the seat when the lifter completely pumped up especially at hi rpm. Bent pushrods and valves.
Best explanation that I could find...
http://www.youtube.com/watch?v=lorANZ1Tptw
Notice how in the example, the inside of the lifter hits the bottom of the lifter body when there's no oil being fed into the lifter?? That's bad....and is what happens when the oil runs out of the lifter too quickly also.
Next notice what happens when the oil stays inside the lifter...not allowing the inside lifter piston to hit the inside bottom of the lifter. That's a good thing....as long as you have not set lifter preload too deep (the amount, in thousanths, that the lifter's internal plunger rests from the top of it's travel....when the camshaft is at zero lift.) If you set too much preload, it is possible for the lifter to pump up too much under high rpm/oil pressure situations. Then, the inside of the lifter can rise to the top of the lifter body...in effect, making the pushrod longer and holding the valves open too far.....not good at all.
The goal is to find a lifter that will not bleed off too quickly, causing noise and less valve lift.....but will also not pump up too much under high rpm and oil pressure situations, causing valve float and bad things to happen with pistons hitting the valves. You want accurate valve control....kinda like a solid lifter....but you want it without the noise of a solid lifter.
Hope this helps make it clear....sorry I'm not too good at explaining it.
Last edited by salemetro; Feb 1, 2012 at 01:33 AM.
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the ls7 lifter is the standard.
the part numbers are different in that it says that the lifter and tray is one part number while just the lifter is the other. you cant buy ls1 or ls6 lifters anymore. if you look up their part number they have been superceded by the ls7 one.
the part numbers are different in that it says that the lifter and tray is one part number while just the lifter is the other. you cant buy ls1 or ls6 lifters anymore. if you look up their part number they have been superceded by the ls7 one.
2007 thru 2010 LS3, LS7, LS7 had lifter p/n 12576400
and
All years of LS1, LS2 ... and 2006 LS7 had lifter p/n 17122490
Is the current lifter for all these LS engines now 17122490?
I don't know how old this chart is, but it can't be older than before 2010 since it references 2010.
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It's not just a matter of noise....it's also a matter of obtaining the most valve lift. Noise means (as I understand it) that your lifters are bottoming out, which means that valve lift is suffering. Personally, I want to know that the cam is able to do it's job just as it was intended.
No matter how perfect the lifter pre-load is on these engines, there's still going to be some valve train noise it seems.
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If all the components in the entire valve train was always in contact with each other, then there doesn't seem to be any way for the lifter to pump up beyond keeping all the components in contact at all times.
Last edited by ZeeOSix; Feb 1, 2012 at 05:05 PM.
I think the valve train noise that most here are talking about is the typical LSx "sewing machine" noise ... not necessarily noise for bottoming out a hydraulic lifter. I'd think if you were bottoming out the lifters it would make some pretty horrific noise ... like when you start an engine after the lifters have bleed down.
No matter how perfect the lifter pre-load is on these engines, there's still going to be some valve train noise it seems.
No matter how perfect the lifter pre-load is on these engines, there's still going to be some valve train noise it seems.
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The sewing-machine noise is exactly the lifter bottoming out. I've heard an LS1 with a silent valvetrain...and it was just that....silent. Granted, it was a cold start and only ran for about 5 minutes....but it was silent the entire time. I'd imagine once the car was up to temp, it could have exhibited some noise...but nowhere near what my car is currently doing.
My LS6's valve train is pretty quiet on cold starts too, but does make some sewing machine noise once the oil is at full temperature. I highly doubt the lifters are bottoming out, especially if the noise is heard at idle when the lifters should have no problem keeping pumped up as designed.
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Verdad Gallardo They acually make MORE noise at idle...when oil pressure is the lowest (about 40psi). As RPMs and oil pressure climbs (roughly 80psi), they quiet down considerably...but some rocker "clacking" can still be heard up to 3.5k. It's defintiely NOT how it should be.
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Sure seems you'd have more than just "sewing machine" noise from the valve train if lifter plungers are bottoming out in the lifter body.
My LS6's valve train is pretty quiet on cold starts too, but does make some sewing machine noise once the oil is at full temperature. I highly doubt the lifters are bottoming out, especially if the noise is heard at idle when the lifters should have no problem keeping pumped up as designed.
My LS6's valve train is pretty quiet on cold starts too, but does make some sewing machine noise once the oil is at full temperature. I highly doubt the lifters are bottoming out, especially if the noise is heard at idle when the lifters should have no problem keeping pumped up as designed.
A lifter having fast leakdown symptoms will experience the most problems at idle and during cruising speeds, where oil pressure is at a minimum. Performance wise, faster leak lifters don't survive high RPM's. But will increase vacuum.
Last edited by Havoc40; Feb 2, 2012 at 01:52 PM.
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I still haven't had a chance to get back under the hood of the car to do more measuring, but it looks like I should be ordering new pushrods shortly and hopefully getting this thing running. It's been over a month now that she hasn't run.
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PS- The Miata is unbelievable. I still lust for a NA with big flares and some wide, go-kart like tires. My buddy has a NB Miata that he just had repainted, I think I forwarded him a pic of your car months ago when I saw your build thread. He loves it.
Here's something that hadn't occurred to me before....When going through the process of torqueing the rockers and setting up the valvetrain, does a lifter have to first be pumped up with oil? Wouldn't a lack of oil in the lifter skew the measurement?
Afterall, there is oil pressure under running conditions.
Afterall, there is oil pressure under running conditions.
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Here's something that hadn't occurred to me before....When going through the process of torqueing the rockers and setting up the valvetrain, does a lifter have to first be pumped up with oil? Wouldn't a lack of oil in the lifter skew the measurement?
Afterall, there is oil pressure under running conditions.
Afterall, there is oil pressure under running conditions.
The lifter doesn't have to be pumped up with oil in order to make pushrod measurements. There is still a spring in the plunger that will push it to the top of it's travel. If a lifter was totally pumped up with the plunger at the very top, that condition might actually skew the measurement if the lifter's plunger didn't compress as the rocker arm is tightened down and forced the valve to open some instead.
When I was selecting pushrod length in my car I had the adjustable pushrod to check my sizes. Once it was at zero lash I took it and measured the size with a caliper. The reason for that is the adjustable pushrod was off on its size. Don't remember exactly how much, but enough for me to wanna make sure. If you have access to a caliper for measuring, that is your best way for an accurate measurement on preload. I wanted .060" in my lifters and with my head setup I needed a longer pushrod than normal. I had to go with 7.550" and those gave me .049" of preload. I also measured the length of the 7.550" pushrods and they weren't exactly their advertised length either. Once again I don't remember exact numbers. Just trying to make the point that without the caliper I could've been pretty far off on preload. With my .049" and my Patriot Gold Dual Springs the motor is a little noisy, but not bad. Also noise is an opinionated statement in this case, so you may not always agree with what people say aren't noisy lol. Hope this helps.
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When I was selecting pushrod length in my car I had the adjustable pushrod to check my sizes. Once it was at zero lash I took it and measured the size with a caliper. The reason for that is the adjustable pushrod was off on its size. Don't remember exactly how much, but enough for me to wanna make sure. If you have access to a caliper for measuring, that is your best way for an accurate measurement on preload.
Comp Cam pushrods are in gauge length, as is their pushrod length measuring tool. Some pushrods, like Manton's, are specified by tip-to-tip lenght ... so when measuring and buying pushrods it's important to know how the tool and manufacturer is specifying their pushrods.
Ahh! I did not know that. I just assumed it was measured by the actual length according to that diagram. I have the Comp Tool also if you were wondering. Thanks for that info.
I will say this though, for me personally I like using the caliper to get my measurements so they're spot on or at least very accurate. That's just me though.
I will say this though, for me personally I like using the caliper to get my measurements so they're spot on or at least very accurate. That's just me though.