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Old 06-06-2010, 07:30 AM
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Builder says 1/4 more on rockers....HHHMMM?

While talking to my builder the other day I had my car idling. Its about 600 miles since stroker build. He says

"Oh those rockers are starting to get a bit loud, give em another 1/4 turn"

Their comps magnum full roller to which he zeroed then 1/2 turn at build. When I questioned him he said

"Oh those will have settled a bit ,a 1/4 turn wont hurt em"

I might be a fussy gus here but isnt the idea to keep things the same? I mean how do I know all wear in has been equal? I dont, so maybe for some that will add up to 3/4, maybe for others the 1/4 I put on will be the only 1/4 on them. If what he says is true should I not go over them all by backing them off ,then coming up to zero and putting the prescribed 1/2 turn on?
The cam is the 270 hyd roller

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Old 06-06-2010, 07:45 AM
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If there not clacking they don`t need adjusted. I set mine 1/4 turn off zero lash with the engine running. However I have encountered in the past when valve train and head parts were new after a initial run in I had to go back and readjust some of the valves.
There`s quite a radius hydraulic lifters can adjust, I`ve seen some go a full 1 turn past zero lash and it ran fine. So to a degree he`s right, you can give them more, but if there not out of adjustment I wouldn`t bother. But if they have worn in they may not be in adjustment anymore as it will change as mentioned after some pieces begin to wear.
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Old 06-06-2010, 08:20 AM
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Quote:
Originally Posted by sooper
While talking to my builder the other day I had my car idling. Its about 600 miles since stroker build. He says

"Oh those rockers are starting to get a bit loud, give em another 1/4 turn"

Their comps magnum full roller to which he zeroed then 1/2 turn at build. When I questioned him he said

"Oh those will have settled a bit ,a 1/4 turn wont hurt em"

I might be a fussy gus here but isnt the idea to keep things the same? I mean how do I know all wear in has been equal? I dont, so maybe for some that will add up to 3/4, maybe for others the 1/4 I put on will be the only 1/4 on them. If what he says is true should I not go over them all by backing them off ,then coming up to zero and putting the prescribed 1/2 turn on?
The cam is the 270 hyd roller


I recently had a similar build w/ a comp 270 full roller and right from the get go I found the rockers a bit noisy. The only difference is , I put it together and knew for sure where I was with adjustment. Also, like what your builder "says" , gave them the prescribed 1/2 turn. But the noise was still there. So I went back in there and started from scratch, again with the prescribed 1/2 turn, making sure the locks were tight. . . . . . same sound. So back here to post about it. I heard everything from, " some motors make noise - some don't" to " its because of the steep ramps on the roller cam" to " try a different oil" to " Give it another 1/4 turn and see what happens" + a few more. You won't hurt anything by giving them another 1/4 turn, AS LONG AS YOU KNOW WHERE THEY ARE. If you choose to tighten them, I would start from 0 lash and do them all JMO. I ended up with a little noise in the end and got used to it. When the engine gets hot( like after running it up to 6500), it is a little more noticable, but quiets back down . I am going to try a little thicker oil. So in the end, 1/2 turn it is for me .

Oh, I forgot to mention, I also have the retro link bars on the lifters, They can make some noise too.

Last edited by Fast 4 Door; 06-06-2010 at 07:16 PM.
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Old 06-06-2010, 08:55 AM
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clatter

I have to use a stethoscope to do it now, but it's better anyway. You can isolate the noisy rockers. I'm old school, and in the day it was 3/4 to full depending on the book. Know the cam specs are different but 3/4 or more still works. I think it more likely that some of those self locking nuts are worn smooth and slowly backing off. I really hope you don't have break-in wear that significant yet. Might swap out for a set of poly locks, and while you're at it recheck your headbolt torque. Duntov

Last edited by Duntov; 06-06-2010 at 07:52 PM.
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Old 06-06-2010, 07:48 PM
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I have found that when you run a roller cam and roller valve train, it is just somewhat noisy and not a problem. If it doesn't get any worse and you have checked them already and found no problem, it's normal roller valve train noise. My retro hydraulic roller and full roller rockers have always had a little noise.
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Old 06-06-2010, 09:12 PM
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On a 3/8"-24 SBC rocker stud, each thread (or each full turn on the thread) equals 0.04166". There is about 0.06000" preload depth available before you bottom the plunger, starting from zero lash. So, if you take one-half turn past zero lash, you have pre-loaded the plunger 0.02083", or about 1/3 the available depth.

From what I read, using half the available depth is ideal, so if you pre-loaded by 3/4 or a turn, that would be 0.031245", or about half the available depth.

I agree with cc82z-28 about valvetrain noise. Unless you have a bone stock cam with bone stock hydraulic lifters, you're gonna have some noise. I don't understand all the griping about valvetrain noise anyway. It's supposed to be a little noisy. It's a hot rod motor.
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Old 06-06-2010, 09:45 PM
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lifters

I agree that 3/4s to a full turn puts us at near mid range. That's where it's always worked for me... I mean that's where I can't hear it anymore, assuming the nuts are still good. I've been on a lot of chevy work trucks,(pipeline guys roofers ect, where they come in skipping and rattling and they've been working on it themselves. And you can tell when the total experience of a young roofer has been on ford trucks.. The lifters are cranked all the way down. It still runs but skips cause one or two of the studs are jacked out and maybe one or two lifters collapsed bent or broke a push rod. But I've been amazed that you could wind off half the lifters 2 or 2 1/2 turns before they clack, giving them time to pump up of course. At 3/4 or 7/8ths I feel like I'm done and don't have to violate my valve cover gasket anymore. Hasn't changed much in 40 years.
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Old 06-07-2010, 04:57 AM
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Quote:
Originally Posted by techinspector1
I don't understand all the griping about valvetrain noise anyway. It's supposed to be a little noisy. It's a hot rod motor.
Oh my good man,its not valve train noise or any noise that bugs this boy. This boys bugged by even the smallest chance of leaving one half of one pony untapped
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Old 06-07-2010, 05:52 AM
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I often do the "zero lash" hydraulic lifter adjustment which is just a old hot rodders trick. It`s messy to do so, so rocker clips have to be used. Get the engine up to temp, pop the valve covers, Back off all the rockers slowly until they just begin to clack, then raise the idle speed to about 1500 to 1800 RPM, then start over from the point you started, very slowly tighten it to the point the clack goes away, then give it another 1/4 turn. Raising the idle raises the oil pressure and pushes the lifter plunger against it`s retaining clip. I`ve used this method on just about all I`ve done. What I read a long time ago was this gives the engine a few hundred RPM`s more in red line and it makes it idle smoother. I dunno about helping the RPM since I never look at the tach, but it does make it idle smoother.
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Old 06-07-2010, 07:22 AM
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Quote:
Originally Posted by techinspector1
On a 3/8"-24 SBC rocker stud, each thread (or each full turn on the thread) equals 0.04166". There is about 0.06000" preload depth available before you bottom the plunger, starting from zero lash. So, if you take one-half turn past zero lash, you have pre-loaded the plunger 0.02083", or about 1/3 the available depth.

From what I read, using half the available depth is ideal, so if you pre-loaded by 3/4 or a turn, that would be 0.031245", or about half the available depth.
Umm, what about the rocker's ratio.
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Old 06-07-2010, 07:30 AM
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If one guy says 1/4 turn and another guy says 3/4 turn...split the difference and go 1/2 turn. Ultimately you have a cushion anyway thats why the lifter is hyraulic....don't overthink it.
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Old 06-08-2010, 08:23 PM
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Quote:
Originally Posted by sooper
While talking to my builder the other day I had my car idling. Its about 600 miles since stroker build. He says

"Oh those rockers are starting to get a bit loud, give em another 1/4 turn"

Their comps magnum full roller to which he zeroed then 1/2 turn at build. When I questioned him he said

"Oh those will have settled a bit ,a 1/4 turn wont hurt em"

I might be a fussy gus here but isnt the idea to keep things the same? I mean how do I know all wear in has been equal? I dont, so maybe for some that will add up to 3/4, maybe for others the 1/4 I put on will be the only 1/4 on them. If what he says is true should I not go over them all by backing them off ,then coming up to zero and putting the prescribed 1/2 turn on?
The cam is the 270 hyd roller
You have the right idea.

Your mechanic just threw something out there, and for the most part he's correct- the hydraulics of the lifter has the capacity to absorb more or less preload. This is built into their design.

But as you've correctly said- you would have no idea of how much preload would then be applied to all the valves, being as how they don't all wear exactly the same. And that's also why you are correct in saying the right way to do it would be to go back and zero lash the valves then add the required preload.

As for the suggestion of judging preload by how many threads per inch, the rocker arm ratio has to be added into the equation. The above statement,
Quote:
On a 3/8"-24 SBC rocker stud, each thread (or each full turn on the thread) equals 0.04166".
is correct, what is not correct as it was explained to me is that the lifter preload would be the same as the amount the nut was turned. The correct figure at the lifter will be 1.5 (or whatever the actual rocker arm ratio is) times the "threads per inch" figure.

Quote:
if you pre-loaded by 3/4 or a turn, that would be 0.031245", or about half the available depth.
should read "if you pre-loaded by 3/4 or a turn, that would be about 0.047", with a 1.5:1 rocker ratio.

Then there's the actual lift applied by the rocker arm. Stock rockers are often less than the advertised ratio (as low as 1.3 range on a 1.5 OE SBC rocker has been reported). And there are aftermarket rockers having differing rates of lift as the rocker moves off the seat, etc.- i.e. the ratio is not uniform from start to finish. This is a small consideration, but should be noted just the same.

Since I know of no one who preloads their lifters based on the stud's thread count, this is largely a moot point- but in the interest of accuracy, I mention it anyway.

As for ~0.030" being 1/2 of the available travel of the lifter, remains to be seen- lifters vary as to their exact amount of available travel, some I have are easily 0.100" top to bottom.

Last edited by cobalt327; 06-09-2010 at 06:33 AM. Reason: Addition.
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Old 06-09-2010, 06:23 AM
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Quote:
Originally Posted by Fast 4 Door
I recently had a similar build w/ a comp 270 full roller and right from the get go I found the rockers a bit noisy. The only difference is , I put it together and knew for sure where I was with adjustment. Also, like what your builder "says" , gave them the prescribed 1/2 turn. But the noise was still there. So I went back in there and started from scratch, again with the prescribed 1/2 turn, making sure the locks were tight. . . . . . same sound. So back here to post about it. I heard everything from, " some motors make noise - some don't" to " its because of the steep ramps on the roller cam" to " try a different oil" to " Give it another 1/4 turn and see what happens" + a few more. You won't hurt anything by giving them another 1/4 turn, AS LONG AS YOU KNOW WHERE THEY ARE. If you choose to tighten them, I would start from 0 lash and do them all JMO. I ended up with a little noise in the end and got used to it. When the engine gets hot( like after running it up to 6500), it is a little more noticable, but quiets back down . I am going to try a little thicker oil. So in the end, 1/2 turn it is for me .

Oh, I forgot to mention, I also have the retro link bars on the lifters, They can make some noise too.
I understand the OP to have a hydraulic roller cam if the wear is uneven enough to make any difference I would have bigger worries than how to adjust the valves to compensate.......and in the quoted post above if by "full" roller you mean solid roller then you are doing it wrong.Valvetrain noise isn't the way to select engine oil weight....LOL

Last edited by BBCMudbogger; 06-09-2010 at 06:29 AM.
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Old 06-09-2010, 03:14 PM
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Quote:
Originally Posted by sooper
While talking to my builder the other day I had my car idling. Its about 600 miles since stroker build. He says

"Oh those rockers are starting to get a bit loud, give em another 1/4 turn"

Their comps magnum full roller to which he zeroed then 1/2 turn at build. When I questioned him he said

"Oh those will have settled a bit ,a 1/4 turn wont hurt em"

I might be a fussy gus here but isnt the idea to keep things the same? I mean how do I know all wear in has been equal? I dont, so maybe for some that will add up to 3/4, maybe for others the 1/4 I put on will be the only 1/4 on them. If what he says is true should I not go over them all by backing them off ,then coming up to zero and putting the prescribed 1/2 turn on?
The cam is the 270 hyd roller
Comps tend to be noisy, the lifters have a higher than "stock" leak down rate which at idle gives them enough time to sink against spring pressure to where they will clack a bit. When the revs come up they won't have time to do this and will quiet down.

The point of the adjustment is to build about as much clearance in the lifter as would be there if these were solids. At about .040 inch per turn 1/2 turn gives the plunger about .020 inch before it hits the retainer clip if it were to be operated at the point of pump up. Pump up occurs when a clearance forms in the valve train to which the plunger in the lifter reacts to remove. If the plunger has enough space in which to move, it will absorb enough clearance to hold the valve off the seat. When you add more turn than specified, this provides the plunger with additional distance with which to pump the valve off its seat. This will move the pump up point lower in the rev range. Sinking the plunger just chases the problem. If you want quiet get some GM stock replacement lifters, but given the 270's lift rates even they may tick a bit. Lifters don't settle unless they are starting an internal failure mode that lets the shut-off valve leak beyond the design limit. All hydraulics back leak a little which reduces both duration and lift very slightly against an equivalent solid lifter cam. If your not racing this is of little concern as it takes a lot of rocket science to overcome the valve train motion that affects the valve the same way as a hydraulic but with a solid lifter because the push rod deflects a little as do the rocker studs, so the motion at the valve is never exactly like the lobe command without composite pushrods, Harland Sharp aluminum or Comp stainless rockers, and either a stud girdle or shaft mounted rockers.

Follow the manufacturer's recommendations for plunger position. Comp tests this stuff till the cows come home and know what and why they make these recommendations.

Bogie
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Old 06-09-2010, 06:08 PM
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lifter noise

Excellent Bogie!,
That read good, but I'm still unclear on a recommended adjustment. Sounds like you're saying they're more likely to pump up and jack valves open if treated like factory hydraulic lifters. You attribute that more to the cam lift/duration or to the aftermarket lifters? Thanks Duntov
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