qwikz28

iTrader: (12)

I'm terribly confused, but that is also because I don't understand the mechanics of a lifter. Are you saying excessive preload would cause valve lift to decrease?

butler

Imo it would hold the valve off the seat when the lifter completely pumped up especially at hi rpm. Bent pushrods and valves.

salemetro

iTrader: (5)

No...and yes. Too much preload will not let enough oil into the lifter at low rpm/oil pressure, and the plunger will hit bottom....having the same effect as shortening the pushrod. But when you rev the hell out of the engine, the lifter will pump up too much....having the same effect as lengthening the pushrod.

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.

ZeeOSix

The chart I attached to Post #5 is a little confusing it seems - maybe I'm reading the footnotes in the chart wrong (?). How I take that chart is that:

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.

ZeeOSix

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.

ZeeOSix

Isn't the only way for the lifter to "overly pump up" is during valve float? Seems in order for the lifter to overly pump itself up, the pushrod would have to loose contact with the lifter or rocker arm to allow the lifter's plunger extra room to travel and over pump up.

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.

salemetro

iTrader: (5)

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.

ZeeOSix

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.

salemetro

iTrader: (5)

I do...you can actually hear the rockers "clacking" occasionally at various rpms.....not all the rockers....but some for sure.

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.

Havoc40

As mentioned before many times on this forum, there are many components that contribute to noise. Block material, manifold, LT headers, etc. Lifter noise is pretty distinctive, and is directly related to the sizing of the lifter internals, oil pressure, oil quality, RPM, and engine temperature. A ticking lifter is the piston bottoming out. How loud, again, depends on the variables I just mentioned.

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.

qwikz28

iTrader: (12)

That explained it perfectly. Thank you. I read the updates in your thread and it seems like you found a good solution for your problem. It seems like your lifters were screaming from the sound of it.

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.

salemetro

iTrader: (5)

Damn, I hate having a vehicle down for that long...I feel your pain! lol

qwikz28

iTrader: (12)

The absolute worst! Especially since all I want to do is move it into the garage for the remainder of winter! Thanks for all your help; you, Havoc, and everyone have been a great help. I'm looking forward to having a day out of this office to make some progress on the car.

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.

gMAG

iTrader: (1)

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.

ZeeOSix

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.

Z28Z06

iTrader: (2)

Subscribed and looking for an expert!?!?

gMAG

iTrader: (1)

This makes sense. Thanks.

Zach99Z

iTrader: (1)

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.

ZeeOSix

The pushrod measuring tool (if it was a Comp Cams) is supposed measure the "gauge length" of the pushrod. When you measured with a caliper, you were measuring from tip-to-tip, which will be a larger number than the gauge length obtained by the tool.

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.

Zach99Z

iTrader: (1)

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.