GREGGPENN

So you went from alum to steel rockers to make sure you had the strength necessary to support your extra lift?

Makes sense.

When you made the swap, did the lifters stay the same? Otherwise, you changed all the variables -- not just the rockers. (Kinda makes me wonder about your extra lift being at least part of the culprit.)

STL94LT1

At that time the only change I made was the rockers, and the increase valvetrain noise was immediate. I tried everything from 1/4-1 full turn adjustment without any noticeable decrease in noise.

Now that I am running the higher lift camshaft and dual springs the noise is even louder.

I have mentioned the valvetrain noise to others and they listen to the car and say it's really not that noticeable. Maybe we are just overly sensitive to every little noise we hear coming from the engine compartement.

turbotim23

I don't know if you know this but it's worth asking. How are you checking lifter for preload? I was told not to do it by twisting the pushrod back and forth with your thumb and fore finger[as some do] but by lifting it up and down to feel for play. I was told twisting the pushrod gives a false reading of what preload really is. That lifting up and down is much more accurate way to tell.

mtwoolford

Is there a consensus of opinion here? Is it 1/4 turn ? 3/8 turn ? 1/2 turn ? 3/4 turn?

Lets hear from an expert who thinks WAY outside the box.

Tuned Port Induction Specialties (TPIS) "The Shape Of Things To Come" in their publication LT-1 HINTS & L-98 UPDATE, at page 9:

"Effect of valve lash on hydraulic camshafts"

" One of the lessons learned (competing in the 1994 and 1995 World Challenge Series) is that to achieve elevated RPM's out of these camshafts (all hydraulic camshafts - flat or roller tappet) is that you need to preload the lash at least two turns below zero and sometimes more....

....Three turns below zero is extreme for the street but two turns is not out of the question. UNDER NO CIRCUMSTANCES SET THEM AT ONE TURN OR LESS" (emphasis added). "

Any thoughts ?

WW7

I have never heard of or known anyone to set the preload at more then one full turn past 0 lash.. The FSM for my 89 says 1 full turn. I don't know if this above statement would be something to try without a little more investigation.. You could do some serious damage if wrong...Also if 1 turn is suppose to put the plunger half way down, wouldn't 2 full turns bottom the plunger out??..God only knows what 3 turns would do...WW

cv67

So whos going to be the first to go 4 turns because more is better

GREGGPENN

There's at least one guy in the LS1 forum who adjusted his LSx motor to .100". That would be well over one turn (if he knew what he was doing). He added it was quiet and performed well. His post was in response to his learning that LS7 lifters needed .060"-.120" preload. (Of course, that doesn't make sense to me because LS7 lifters are referred to by many as short-plunger lifters). Plus GM Performance and COMP both say less preload is required for their short-plunger counterparts.

You gotta think the first stage of overtightening would create an open valve during the combustion stroke. Significant power and/or backfiring would be present. The next level would be contact from the valve to piston.

I might call Clay and see what the Insider Hints scoop is. On more than one occasion, he's shared his views/opinions on advice published by TPIS.

AVL94LT1383

I have the .579 and .588 lift with 1.6 RR comps. we are at 1/2 past 0 lash... What about the 18 lbs tq spec.?

Calderone

i've just did 1/2 past 0 lash , and if i have to readjust looking for less noise
i won't never go past 1 turn ! but that's me, maybe its my ignorance
but at one point in the past i overtightened and the engine ran very hot
this is off topic but ...it didnt stay that way for long because i had a problem
that the valves loose their adjustment very quickly, in a couple of days

STL94LT1

That sounds like the spec for the non-adjustable LT4 roller rockers.

engle1147

Got false/burst knock?
It doesn't look like you've got too much stuff in the way of pulling the valve covers so it should be a relatively quick/easy job. Pull the covers and add 1/4 turn more for each rocker and see if it makes a difference.

GREGGPENN

I just got off the phone with Clay@TPiS. He's their main engine mechanic as I understand it.

He clarified that the quote above can be misleading since it's intent was primarily for high-rpm racing applications. Under those conditions, tightening the lifter to the point it verged on performing like a solid lifter was found benficial.

On the phone, he said more clarification may have been beneficial -- especially for the statement starting with "Three turns is extreme for the street...." That clarification would have stated one turn is really about their recommended "limit" for a street application.

In talking about so many people/companies recommending as little as 1/4 turn, I (we) came to the conclusion that builders do this as a safety margin. That's because, at higher rpms, a lifter can get "pumped up" and act more like a solid lifter. We all know solid lifters don't get cranked down (past zero lash) like solids do.

So, the conclusion would be to consider your application and use a setting that coresponds to the application. The higher rpms you turn, the less lash you should use. That's because it helps to avoid valve float. (Of course their are other methods for accomplishing this as well).

For street applications, Clay has no problem with (and sounds like he'd recommend) a tighter lash setting when you were interested in getting rid of excess noise. Noise comes when the lifter rolls off the cam nose. There's an instant where slack enters the lifter/p-rod/valve setup. When the spring "slaps" it back together, you get noise. With a bit more preload, you MIGHT be able to reduce some of that noise.

Both TPiS and Bullet say noise from roller rockers does not come from bearing clearance problems. It's more from the design/geometry of a roller vs "slider" factory rocker. And, an LS7 lifter should be treated the same (with regard to preload in our motors).

Note: I will send Clay a link to this post (and the entire thread). I let him know I would be doing so in case my interpretation of our conversation needed amending/correction.

Calderone

Good info Gregg ! Im currently using 1/2 turn , i might try 1 full turn
Thanks !

Orr89rocz

LS7 lifters i've used 1/4 turn with good success and later went to 1/3-1/2 turn. I have had the rockers come loose before and needed retightened. My turbo motor did the same thing so I went 3/4 turn or so. Less makes more power but can be noiser or prone to backing off

AVL94LT1383

Thanks I always wondered why the Lt4 said 18 lbs vs turn....but did not ask.... by the way I have the beehives along with the other listed items and it is more "springy" sounding if I can make up a word. The more noticable sound vs stock has not concerned any one listening which included three very well know engine builders in my local area.... what ever that is worth. The viedo/sound did not sound too far away from what I hear in my experence.

THE 383 admiral

Measuring Is a great way to start!!!!
I'm sure your aware...
But I always adjust my Rockers by backing off until you hear the slightest tick.. then adjust
till the tick is Gone.. this is my Zero<> then I adjust 1/2 - 3/4
JMO takes longer but.. Well worth the time!!!!!

korvette4u

hi gregg, the point of the matter is: depending on BRAND of lifter MOST plungers inside a hydralic lifter will travel up to .80 thousands.. the idea is to be in approx the middle of that trAvel about .030- 040"s . yes the threads will vary slighly using 3/8" over 7/16" , however using a dial indicator to set. TAKES THE GUESS out of how much of a turn is required. once the first lifter is set to the .030 you will note how much was turned to achieve that depth.. PLease keep in mind that the roller of the rocker must be in the center of the valve stem when closed.. this is vital part of an observation that should not be overlooked..if so can cause serious damage!

usually with 1,5 @ .500 lift will add .333" with 1.6 rocker
using rockers of larger lift can be calculated: use this my lift caculator

the final ingrediant is ZERO VALVE LASH.. how is it determined? most will use the tighten method untill the lifter rod becomes difficult to turn..although this may work for those that have to "NACK"..THE BEST WAY is to tighten untill "THE FEEL" of the movement up and down has stopped. this "FEEL" and dial guage combination is hard to argue with!

.

your builder should have equally told you in thousand of inch as well

using the above combo with 1.6 rocker is .588 lift, my question, did you dial in your cam? were new heads used/or resurfaced( how much removed)? was the block decked? basically have you determined piston to valve clearance? mininium .100" depending ,, established by the clay method.
my next concern: are the springs too soft and do these compress enough with out binding? usually the CAM spec will suggest a combination best suited, spring must have enough resistants to over come lift and float.

seems the 155#@ 1.800 is closed installed lbs/ hieght, and the compressed open height 352#@ 1.280 a difference of .520 " is your problem.. not by much ! only .068" too much to function without binding.. may need to change springs! maybe use 185#, these are good to .650"

hope this helps

GREGGPENN

Sorry for the confusion. I don't have .588 lift. The .544" number listed is WITH my 1.6 rockers.

The heads were new, but still cut down to 56cc. (I did this before deciding to go the 383 route.) The cam was dialed in. Clearance was measured. And, push-rods were measured too. I have .040 quench with 20cc inverted dome pistons.

I don't believe I have any issues with setup/geometry.

383vett

I've been running Crane gold rockers and Crane hydraulic roller lifters for years (unfortunately no longer available). I use 1.5 on the exhaust and 1.6 on the intakes. The Crane instructions call for 1 1/2 turn past zero. I have been doing this for 10 years+. I shift at 6500, the motor has been run to 7000 and I have never had any valvetrain issues. Willie

korvette4u

ok. .040" cold? the spec on #155 binding occcurs at .520, that makes .024" too much lift: Nominal Open Pressure & Height should not be exceded.. spec i found are here: check spring specs here,,,BTW just trying to help up to you now..