Your thinking would be correct, a longer PR will bring up the PR end of the rocker, which will also bring up the axis point of the rocker and give it more clearence on the outside egde of the retainer top.

I don't have a set of 7.50" PRs, but could at least set up the adj PR to see what the wear pattern would be. I'm going to go ahead and swap the 7.15"s out for the 7.35" when I take it back apart.

 

I recently installed the 1.6 Comp Magnums with my stock springs and they aren't one bit louder than the stockers were. This is im sure due to them not being full rollers, but i def picked up around 15 hp with them, fully noticeable (comp claims 15-20hp). They are the only type i have tried so im not sure whether there is more hp to be gained from the pro comps or one of the aluminum styles. But, there quiet as a mouse, no falsely detected knock (from noise), no mods needed for valve covers, and im fully happy with the mod. Def one of the best dollar per hp mods out there!!!

- also.... im still not even close to coil bind with my stock springs!

 

Ok, I finally had time to swap out to the longer PRs. They are not 7.35" like I thought, I measured them and they are 7.30" Comp Magnum 7609's, getting old I guess, could have sworn they were 7.35s.

Anyway, the noise is a bit quiter, but these things still chatter pretty good just right at 1500-1800 rpms under load. Sounds better at idle and unloaded for sure.

I found 2 or 3 rockers that had just a tad bit of scuffing where it could have been very very slightly touching the spring retainer, I mean it was a very tiny mark.

Now with that finding, it still does not make sense that they were noisey with the aluminum rockers with the beehives as they had plenty of clearance even with shorter PRs.

Any longer PR and I will be pushing it as an increase in PR length means the rocker nuts will move that much higher and may start to touch the valve cover, I ll also need longer studs as I only have about 5-6 threads now with the 7.30s.

I may go back to the aluminum rockers and the beehives with the longer PRs..still paranoid about that .020" clearence on the valve seals and inner spring with these dual springs.

 

Your recent results show that you're moving in the right direction. Not only can contact between the rocker arm and the spring retainer cause noise, it can unload the valve locks and cause engine failure should one of the locks pop out. No matter what you have to do do, any contact between the rocker arm and the retainer must be eliminated. You'll need a minimum of .030clearance.

I'm using ARP 200-7202 rocker studs which have a effective length of 1.90" The studs that came with my new Dart heads came with 1.75" studs. I anticipated the need for a longer stud, so I ordered 1.90" from Summit, however, once I mock up the valve train I may need to go to even longer with 2.00 or 2.10 studs. It just depends on the tolerance stack and how things line-up and clearance.

On my 388 with Scorpion 1.7 RRs, and small base circle XFI cam I had to buy GM Approved Proform covers that are 1/4" taller to give me the poly-lock clearance I needed. I tried making the stock covers work, but I soon realized it wasn't gonna happen. To me correct valve train geometry was essential, not which covers I ended up running.

Going with thinner poly-locks or ones giving less thread engagement was never an option just to get the covers to fit. If one of the poly-locks fails, it will usually be at high rpm and you can probably imagine what carnage that would cause.

The difference between the retainer and the valve stem guide or seal should be greater than the valve lift, according to CompCams. "Must be greater than valve lift" is the exact quote. So since you have .020 you're fine. Changing that to get more clearance would call for an increase in valve spring installed height, different springs, changing to a lower lift cam, less rocker ratio, etc.

My thinking is 'What have you got to lose?' If a still longer rods and studs will give you the clearance you need and eliminate the noise you're experiencing, then it's the right thing to do.

Comparing one engine with another may sometimes be helpful, but in your case it doesn't seem to be. When using after-market parts, sometimes what works on one engine won't work on another. Like in raising my four kids, I treated each one as an individual; what worked with one of them didn't necessarily work with another.

Keep us posted.

Jake

West Point ROCKS!

 

I think you may have misunderstood what I meant on the valve seal clearence, I was talking side to side cleareance since the inner spring has such small I.D., the valve stem seal just barely fit up inside the spring. Don't remember the exact measurements, but the difference between the spring ID relaxed and the valve seal diameter was only .020", thats .010" on each side.
Not that it is causing any noise, but would hate for a spring to pull off the seal and get caught up in the spring.

I'll experiement with even longer PRs in the coming weeks as time permits, but with the 7.30 I can see plenty of daylight now between the rocker bottom and the retainer top and there appears to be plenty of clearance all the way around and valve open or closed.

I'll see where a 7.50" pr puts the wear pattern, I may have some taller studs also somewhere in the garage that used to be on the truck when it had 1.52rr maybe they'll be taller.

 

Oh, okay, I NOW see what you mean about the seal clearance. I'll have to do some research to see if .010" is sufficient.

Yes, the springs will dance around unless they're fitted into cups or locators. Here's what the March, 2008 Chevy Hi-Performance magazine says on page 28: " Use of a spring locator, or cup, is mandatory on alumnum heads, and not a bad idea in any case."

I use CompCams' cups.


Jake

West Point ROCKS!

 

i have pro mags cc306 987 springs and you can't here my rockers a bit silent ..just like stock love it ...its the junk beehives ..lol

 

With all the swaps he's made, I'm not sure, now, which springs he's running.

He might want to check LS1TECH.COM and LTXTECH.COM because there are some other guys on those forums who are also complaining about the beehives causing a noisey valvetrain. Personally, I don't know if they are the cause but some others are convinced they are.

Maybe reading their posts and maybe sending a PM may shed some light on his problem and how to solve it.

Jake

West Point ROCKS!

 

I'm running the Comp dual springs currently. I did have beehives on there but swapped back to see if that was the problem. The cc306 cam does not have the aggressive lobe ramps like the xfi cams or the LPEs.

 

From CompCams and other articles I've read, the XFI lobes were designed for beehive springs and 1.6 RRs. I just read about that a few days ago in an engine build-up article.

Now I'm wondering if, when you swapped the springs, you set up the recommended installed height so that you'd have the correct seat pressure? Also, if the spring rate is correct for your cam.

Which CompCams springs are you running now and what installed height/seat pressure were they set at?

There's got to be an answer to this problem.

Jake

West Point ROCKS!

 

Can't remeber the exact model, they were the popular spring to get before beehives, they were for .650 lift, have around 420lbs pressure at 1.15" and are installed at 1.80" with around 165lbs seat pressure.

The beehives were installed at 1.75". Seat pressures are around 130 and 330 if I remember correctly, probably a tad higher when closed since the install height is shorter than the recommended 1.80". Yes the beehives are supposedly for the aggressive ramp cams.

 

Those numbers seem good to me, I can't see how they could be the cause of the noise.

Maybe it has to do with lifter preload. I recall reading a post that said Crane issued a Tech Bulletin saying increased preload would cure a noisey valve train. Supposedly this was issued by Crane a few years ago. I never actually saw the bulletin though.

I believe I saw it on Gofastnews.com on one of the Forum boards there, where guys were trying to solve the same condtion as you are. If you have time you might want to try to find it. I'll do the same and if I find it, I'll post.

Jake

West Point ROCKS!

 

I've looked for a while and can't find anything from Crane about it or on gofastnews. If you used less than a 1/4 turn I could see that helping, but mine on this last go around I set them to about 5/8 turn. All of them are very solid at the 0 lash point, had to use a wrench with a bit of pressure to get them to turn the additional 5/8 turn pasted 0.

 

I'm wondering about that "a bit or pressure" part' that doesn't seem right.

Are you using stock lifters?

Are you sure the lifters were riding on the heel of the cam lobe when you established ZERO lash and set the preload?

What was the specific method you use to find ZERO lash? Was it like this:

First off let me say that there are seveal different ways to set lifter preload and all of them will work, but only if done correctly. The difference among the different methods is that one method is less error prone than the others.

The method shown in many manuals, like Chilton's etc., will have you moving from one side of the engine to the other trying to identify and set different lifters. Doing it that way makes it really easy to mis-identify one of them (you'll adjust an intake when you should have adjusted an exhaust, etc.) Only after the engine is started will you find that you'd made a mistake, then it becomes the task of finding out which one was set wrong.

The least error prone method is the one I'm writing about now.

Okay, here's the procedure:

The goal is to adjust the rocker arm adjusting nut enough so that it depressess the pushrod and thus the lifter plunger .030". Since it would be very difficult to actually measure that amount - requirng a dial indicator with a magnetic base, etc., turning the adjusting nut a certain amount will work just fine.

A word of Caution: If the engine has been run, before using this procedure, you'll need to loosen all the rocker nuts to relieve any pressure on the lifters and wait about a minute. This gives the lifter plungers time to travel back to the top of the lifter and not be depressed. If you fail to do this, you could have a false ZERO lash position which will effect the correct preload. More on ZERO lash will follow.

Most importantly, in order for the lifter preload to be set correctly, the lifter HAS TO BE on the base circle/heel of its camshaft lobe.

Since there's no way to actually SEE if the lifer is on the base circle/heel, you watch what its companion pushrod does in order to know. You watch the intake to set the exhaust, then watch the exhaust to set the intake.

May sound crazy but that's how it's done.

To begin, install all the pushrods in their respective lifter and set the rockers and adjusting nuts loosely in place. Then you'll need a way to turn the engine in it's normal direction of rotation. I use a ratchet, extension and socket on the damper nut. Having the spark plugs removed will make the engine much easier to turn too.

Start at the driver's side, front, very first rocker, which will be the #1 EXHAUST. We'll be setting that one first.

Grab the pushrod of next to it, which will be the #1 INTAKE pushrod, with your thumb and index finger so that the pushrod can be moved UP and DOWN.

Turn the engine while feeling what the #1 INTAKE pushrod is doing. That pushrod will, at some point, begin to move up (indicating the INTAKE valve is beginning to open) and then down.

Just before that pushrod is all the way back down, STOP turning the engine. The actual point that you STOP isn't all that critical, just as long as the pushrod has moved more than half way back down.

With the #1 INTAKE pushrod in that position, the #1 EXHAUST lifter will be on the base circle of its lobe.

Now, back to the INTAKE pushrod being almost all the way back down - Move your hand to the #1 EXHAUST pushrod and begin to gently move it up and down with your finger/thumb while at the same time begin to tighten the #1 EXHAUST adjusting nut.

When you reach the point that the #1 EXHAUST pushrod can no longer be moved up and down you've found what we call ZERO LASH.

It's now time to set the lifter PRELOAD on the #1 EXHAUST lifter. Most use 1/2 turn of PRELOAD, so turn the adjusting nut 1/2 turn more from ZERO LASH. This'll depress the lifter plunger and give you right at .030" of
PRELOAD.

1/2 turn equals the handle of wrench at, say, 12 o'clock, then turn the wrench until the handle points at 6 o'clock.

If you're using Poly-locks, once that 1/2 turn is made, tighten the allen head poly lock with your allen wrench. Make sure it's tight!

That one's done.

Now we move on to setting the #1 INTAKE.

To set the INTAKE, we grab the #1 EXHAUST pushrod (the one we just finished setting) with those same two little fingers - or you can just watch what the rocker is doing - either way works.

Begin, again, to turn the engine over manually while watching the #1 EXHAUST rocker or feeling its pushrod. AS SOON as you see the #1 EXHAUST rocker begin to open that valve or feel the #1 EXHAUST pushrod begin to move UP, STOP. You just found the point that the #1 INTAKE lifter is on its base circle of its lobe.

Now grab the #1 INTAKE pushrod with your index finger and thumb and begin to gently move that pushrod up and down as you slowly tighten its adjusting nut. When that pushrod can no longer be moved up or down you've found ZERO LASH for the #1 INTAKE.

Again, tighten the adjusting nut an additional 1/2 turn to set the .030" preload and tighten the allen head screw, TIGHT.

The #1 INTAKE and #1 EXHAUST are now set. Now move on to the very next pair, #3s and do the same thing. Continue working down the line to #5 then #7.

Once done, move to the other side of the engine and begin at the very first, front rocker/pushrod (#2) and repeat, going straight down the line. After you're finished with #8 EXHAUST, you're done.

If you just do one after the other, straight down the line, you won't skip any and each will be set properly.

JUST REMEMBER: The valve arrangement is EIIEEIIE with E=EXHAUST and I=INTAKE It's important to know which valve you're working on, an INTAKE or an EXHAUST.

Since the lifters had been run and had oil in them, before beginning the procedure to find ZERO lash, did you wait a minute or so to allow time for the lifter plungers to rise back to the top?

Jake

West Point ROCKS!

 

Stock lifters, second set that have been in there over the last 2 years. The stockers always are very firm once you hit 0 lash. The LS7 lifters seems to never hold any pressure, you could have tighten the poly lock to 1 or 2 turns on those if you desired. The stockers have always been rock solid once to 0 lash, they are that way on the truck too.

That has been the procedure I have used in the past, but after doing the spring change I've started just going to TDC on the compression stroke of #1 and doing both I and E then rotating the crank 1/4 turn and going on to the next one on the order of 1-8-4-3-6-5-7-2.
Much easier due to less turning the crank when the spark plugs are still in.

You always verify that the correct cyclinder is at TDC compression because the exhaust value will be open on the 5th cyclinder up in the order from the cyclinder your working on.
If on #1, then #5 exhaust will be open.
on #8, then #7 exh is open
#4 then #2 exhaust is open
#3 then #1 exh is open and so on.

I rotate the pr and lift up and down on the rocker end to make sure when 0 lash is achieved.
If overshootng the 0 lash the engine would be idling rough, if not enough to run rough it would cause a noisey loose valve train.

Also keep in mind, the noise is loudest at the 1500-2k rpms range when there is a light to no load on the engine, so I find it hard to beleive that springs being weak etc, would have anything to do with it except from a harmonics point of view.
At those rpms, a door spring should be able to keep the valves from floating