The Alchemist

iTrader: (19)

I agree with everything you are saying, but too many people forget to do the last step, and measure. Just like the fiasco with piston to valve clearance. People want to be able to bench calculate what they have, and that's great to get a ballpark idea, but most people simply rely on the fact that the shop that sold them the mega monster cam said it would fit, so they run it.

Well, just because it fit, doesn't mean the motor is going to live.

And why do you think that with running 0.030" lifter preload is going to cause the valvetrain to go to ****... please explain, I'd like to hear your reasoning, because again, I think it's more scare tactics than anything. Have you see a motor on a spintron with only 0.030" preload causing the valvetrain to go to ****? I'm a chemist, so I rely on people who actually know what they are doing and who aren't trying to sell me the latest and greatest to get advice.

PREDATOR-Z

Because of lifter pump and bleed cycle.. With light preload, agressive ramps and higher rpms, the lifter might be unnable to control the valvetrain and result in valve fluttering or float.
This is relative to type of lifter used. OEM range is ~.080>.100+
Less increases tappet noise which we both know is metal to metal. Noise cannot happen without friction, time will eventualy cause failure.
Different lifters require different preload range, exemple is Comp Cam "R" lifters Vs 850-16.
2 different animals.

Since you are a chemist, then you are familiar with oil grades and even that has an effect on lifter operation and valvetrain stability.

The Alchemist

iTrader: (19)

I hear what you're saying, but too many people don't even bother to check to see what the zero preload length really is.

Just like any theory, you need to prove it with data via test results.

Jessica

Good posts boys... looks like you kicked the internet lore straight in the ***** with actual data.

Some people need to stop making 10,000+ posts and actually go do something.

This post right here is flat out a flaming pile of POO and even the quoted numbers that serve as DATA are WRONG.

Eskimo

iTrader: (9)

You're basing all this talk upon one assumption... That the OEM spec of .100" preload *is* the best for performance and high RPM stability. There's lots of things that are spec'd by the OEM that are not the best for performance, but were done for emissions reasons, crashworthiness, fuel economy, etc.

Let's also not forget that we've changed from the nice mild lobes of a factory cam to sharper, taller lobes. What makes you think that the .100 is still appropriate?

I'd really like to know what your actual, first hand experience is that leads you to insist on this .100" preload number. I can tell you as a fact that my own .035" preloaded engine's valvetrain is quiet, relatively speaking, despite the lifters moving 20% further and quite a bit faster than they did before. Stock lifters, stock rockers, larger diameter 7.350 pushrods, and little 'ol PAC beehive springs.

We're putting my car on the rollers this weekend to get it tuned after the cam swap. I'm sure with your knowledge, you'll know what a valvetrain going to **** looks like on a curve. Want me to post the chart? I can guarantee that mine does not have that kind of curve.

Oh, and to the poster who asked "How can the vendor expect you to order pushrods with the cam if you have to measure it" - That tells you something about the vendor now, doesn't it? "Close enough" is good enough for them.

The Alchemist

iTrader: (19)

What scares me even more is the "do I have enough PtoV based on my current setup", or "will this cam fit" and rely on the vendor over the phone to be able to make the call. Will it fit is very different than will it run and not grenade in the first 1000 miles.

PREDATOR-Z

Assume I have never done it (humour me if you like ) and run me through a step by step as to how you determined that ammount of preload. (.035)
Please do not skip any steps and list all parts, measurements and methods used to get that reading and therefore your choice of "thick" 7.350 advertised pushrods.

"You talked the talk, show us how to walk the walk"

I know this might be a long post for you; but hey, you have done it, so consider it as a valuable contribution to the LS1tech community.

20% further, that is 0.31" smaller than stock base circle, man that must be some serious lifts you are using to have a base circle of 1.24", I thought you were running a hydraulic cam. Did you measure that too ??

willyfastz

There's really no reason for him to explain to you how to measure for correct pushrod lenght. It's really quite simple as you should know. He also probably means "thick pushrods" as in 11/32" diamiter verses the little 5/16 that is sold as the norm.

And I'm just guessing but I'm thinking the 20% more travel would be from the increased lift of the new cam.

The Alchemist

iTrader: (19)

It really is quite simply measuring zero preload. Then you decide how much pre-load you want, and add that to the zero preload measurement, and voila.

How to measure preload is simple, I'd like to see or hear some data of why you think having 0.030" preload is going to cause my valvetrain to go to ****. I don't buy it, and will have dyno numbers and graphs to prove it.

And who's to say 11/32" is thick, I went thicker, but don't tell anyone.

PREDATOR-Z

Why not? 304 posts won't hurt and since he has done it and measured it, I'm sure many other poeple besides me would like to know how it is done "properly".

See, according to his post, I type too much, I should just go work on my motor, and I have little or no first hand experience.
So, first I need to learn how to do it, before I go practice

On the other hand, I really want to know how he got .035 preload on a non adjustable OEM rocker system (meaning 7.315 measurement on all his valves) with a cam that obviously has some amount of lift in it and 243 heads (unknown valves).

(the 20% part was for him to tell me his cam specs or at least the lobes he used )

On top of this I gave a range of preload on stock LS1 liters of .080>.100. Somme poeple like .060>.100
I never said IT HAS TO BE AT .100
Why this range? because OEM lifters were not designed for the lifts most of us are using on our cams and the high spring pressures make the bleed faster.
If a lifter bleeds faster and has light preload, it CAN find it harder to pump fully to maintain adequate pump up and the pushrods in continuous contact with the more agressive lobe. When the preload is in the .080>.100 range, it has an easier time to do so at reasonable rpm. (reasonable is not 7000 rpm)

The Alchemist

iTrader: (19)

QUOTE: On the other hand, I really want to know how he got .035 preload on a non adjustable OEM rocker system (meaning 7.315 measurement on all his valves) with a cam that obviously has some amount of lift in it and 243 heads (unknown valves).


Are you serious? You don't know how to get 0.035" preload? I got 0.030" preload simply because when I measured (3 different pushrods) I found that zero lash was 7.318"-7.322" and with a 7.350" pushrod, it gives me a preload of 0.028-0.032".

Your whole 'bleed down' theory is crap as well. According to your theory, the lifters will bleed down while running which is a lie plain and simple. There is plenty of oil pressure to keep the lifter pumped up and seated against the pushrod.

Where are you getting this bleed down info from, please enlighten me, because I've talked to engine builders and they disagree with you.

PREDATOR-Z

It is that simple, so explain it, simple must be short then.
Ok how do you get 0 lash on all your valves?

And for Pete's sake quit putting words in my mouth, where did I say your .030 preload is going to cause your valvetrain to go to ****?
In post # 20 I said that OEM (meaning in a stock motor), preload is close to .100. If you reduced that peload (in a stock motor) to .030, the valvetrain will go to ****. That is in a OEM motor, not yours.

In another post, I said that YOUR .030 preload works for you for a reason, but YOU still do not know why? You measured it (assuming you did it correctly) and that is what you chose.

Look, I gave you guys the clue to the whole discussion (NON ADJUSTABLE ROCKERS). There is no way in hell you can set the optimum preload with those on all valves, you can only be in a ballpark, and to add to that; unless you have a no split cam (meaning same intake and exhaust duration), you HAVE different base circles on int/exhaust and therefore different preloads if you use the same length p-rods.

I did not bash anyone in this whole thread, but you guys had to, to prove your point. So I am asking: Can you prove your point with numbers and measurements (since you measured)? maybe by doing this exercise you'll find out why .030 works for ya, that would be something wouldn't it?

PREDATOR-Z

See you are doing it again. Where did I say that lifters bleed when motor is running? You are only reading what you wish.

Tell me how you set 0 lash and then I will tell you how many times you need to bleed your lifters to do so.
To get 0 lash you need to be on the base circle, tell me how you did that? And don't tell me your piston was at TDC, because how would you know with a dampner that has no timing marks? You can, but there is a way, come on spit it out
Were your lifters pumped? How? was your motor warm? Ok so you measured once.
And then?

The Alchemist

iTrader: (19)

Actually, I do have a single pattern cam, so that's why it works for me, but again, I measured multiple times on the same cylinder to ensure I was on the base of the cam and came up with the same measurement each time. Trust me, I'm not a rookie at performing measurements. The level of my precision and attention to detail would surprise you.

Let me ask you, do you trust that medication you take? If it's made by J&J you can thank people like me because of my attention to details.

And for the record, you did say that with 0.030" preload, my valvetrain would go to ****. I guess you mean running stock pushrods, but then again, stock pushrods have 0.085" preload.

willyfastz

You can find zero lash with the non adjustible rockers. I assume you know that but just want to see if the other guy do also.

And at zero lash your not putting any pressure on the lifter plungers so they will stay up just fine for measuring. Like they said once you have zero lash you just add the preload desired and order the new pushrods.

We've checked some stock engines (bone stock) and found .150 preload from the factory. There's no way that that is any good for the valve train. With that preload you practicly had zero plunger travel.

And I've never heard that it took .080 - .100 of preload for the lifters to pump up. I always thought that oil pressure is what pumped the lifters up. Ever run any Rhodes lifters? If not they bleed off at lower rpm's to smooth the cam out a little and increase low end performance. But they pump back up as the rpm's increase. All this is done with oil pressure not the pushrod lenght.

PREDATOR-Z

Exactly,

Just let me clarify that .080>.100 is the range I recommend for street. A range that I've used with stock LS1/LS6 lifters (not LS7).
What I meant also is that in the .080>.100 range it is easier for the lifter to maintain pump up instead of a lighter preload like .030

Wouldn't it be easier to just explain everything, he generalises and still does not show us step by step procedure he took to come up with that measurement.

Guys, I'm 46 years old and a drag racer by hobby/love. I've been around Chevys since the early 80's. Different poeple have different ways of doing things. I have mine acquired through years of practice and fu8K ups.
I am just giving my way of doing things and I am not bashing any critics (unlike some).
Bottom line, poeple will sift through and decide for themselves.

sroach20

iTrader: (31)

i did .100 with the ls7 lifters and my valvetrain is quiet. on my previous setup i had around .040 and it sounded like a sewing machine.

Eskimo

iTrader: (9)

Wow, I missed a lot by not checking the board yesterday.. I was out working on the car.

I "Set" my preload by ordering my pushrod length based on my zero-lash measurement + .035".

I don't think I need to (nor will I, since you can do a google search and find the steps needed) explain all the steps involved in how we had degreed the cam earlier, and we had a degree wheel already installed to verify we're not on the lobe, and rotated the engine around onto the base circle of the cam, since that's not required... But since the wheel was on, we used it. We then slid in the adjustable pushrod.. Then torque the rocker to spec, since it's a non-adjustable, pedestal-mount rocker. Then we expand the pushrod only to zero lash, loosen the rocker, take out the checker, and measure it... Repeat as necessary. Take that number, add your desired amount of preload, and viola.. you have your pushrod length(s) to call any of the custom pushrod makers with, and order them. (Yes, you can get custom length PR's, and it won't cost a fortune!)
Or, if your desired preload puts you close so a stocking size, you could order a stocking length from someone like Comp. And yes, my pushrods are larger than 5/16". They work, and don't deflect nearly as much as a 5/16" pushrod does. (Resistance to deflection goes up far more with diameter than wall thickness..but you, of course, knew this. Or do you? What size and wall have you been telling people to buy..and why?)

Am I leaving some details out? You bet. The only reason I even went to this level of detail is because you still haven't answered what reasoning you have to believe that .080-.100 is the best amount of preload to run. Or are you "concerned" that the lifter wasn't fully pumped up and may have fallen slightly during our measurements? It didn't.

yes, 20% as in 20% more lift.. more lift = the lifters move further. Stock cam is .498 lift at the valve.. .293" at the lifter. New cam, .610 lift.. .359" at the lifter. You can do the math from there. By the way, who said my base circle is 1.24"? And yes, while we were degreeing the cam in, we did measure the lift, just to verify the cam card. Why? Because it took 30 seconds, and I was interested to see. Using a dial indicator is a pretty easy way to do so.

I took my .030" preload recommendation from more than one engine builder, all of whom have plenty of experience, knowledge, and who put their name on the line with every engine they build, and that win championships. It's my choice whether to listen to them, or listen to people like you. I chose the former.

PREDATOR-Z

See, that is the difference between us, you listen to someone else, I listen to my experience.
Keep up the good work, I'll do the same.

Eskimo

iTrader: (9)

Good job also "reading only what you want" and ignoring all the specific questions I've asked in that post.

And my own 20-odd years of experience has taught me that just doing things yourself doesn't make them right - it only makes you experienced. What are your accomplishments that make your opinions and advice so much more valuable than anyone else's? (championships, records, etc..)