Roller Rocker Arm Situation

[idahovette]

Have you talked to Scorpion manufacturing about this or did I miss that?

 

[Ronno6]

Have you talked to Scorpion manufacturing about this or did I miss that?

I did.
Mr. Norm said that he has heard of this before.
He recommended slotting the valve cover perimeter holes in order to move the covers up as much as .040" While that would take care of the symptom if done correctly, it did not preclude the possibility of the cover being installed incorrectly or possibly slipping down as gaskets shrunk,etc.
I would rather address the problem rather than the symptom.

 

[climb-101]

Any reason to not get a set of tall valve covers?

 

[Ronno6]

Any reason to not get a set of tall valve covers?

See post #55..........

the top is not where the interference is....height is not the issue.

 

[Honky Kong jr]

See post #55..........

the top is not where the interference is....height is not the issue.

I ground the corners on 2 of mine they didn’t mind

 

[Ronno6]

I ground the corners on 2 of mine they didn’t mind

Who were "they," the rocker arms or Scorpion?
I pitched that notion to Mr. Norm at Scorpion.....he was less that enthused...

 

[Honky Kong jr]

Who were "they," the rocker arms or Scorpion?
I pitched that notion to Mr. Norm at Scorpion.....he was less that enthused...

Any time you find a flaw in ones product they will be less then enthused about a simple solution

 

[Ronno6]

Just am update: checked the rockers o the other head and 7 were spot on, 1 slightly high.

Pushrods all checked to be the same length; valve stems all the same height.

 

[Ronno6]

Well,
After all these trials and tribulations, I may have identified a culprit, if not THE culprit:
ROCKER ARM STUDS !!
PBM 5183
These were furnished as part of my engine build kit. I am not impressed.........
Whilst removing them to shave the ears off my guide plates, I observed noticeable "wobble" of the studs.
Neat as I can measure, the TIR on these puppies in around +/-.012"
That can yield adjacent studs being out of line by up to .024", possible even more!
These numbers my even be greater. I have read that some are out as much as .030" !!
This does not indicate a bend; the gap is parallel from tip to base of the upper portion of the stud.

Looks like a set of ARP studs (.005" advertised TIR )

Stackup of tolerances indeed!

 

[Rusty Nail]

/thread.

Good job. Wish ida thought of that. That's the problem!
Gawl dang summit. Don't get me started!

Jeg's > Summit

xc_hide_links_from_guests_guests_error_hide_media

 

[QBuff02]

I know I'm late to the party here, and it's been awhile since I've posted but im going to add my .02 to this discussion. For starters, you do have an alignment issue, that's a fact, as it's been discussed here, aftermarket heads change the geometry and location of the intake and exhaust ports in a lot of cases. The problem you are seeing with the misalignment of the rocker arms is a simple fix, and pretty much all manufacturers make a set of offset guideplates to combat the very problem that you are seeing to correct that issue. It's a simple thing of what heads you have generally have a recommended/required parts list to go with them, most of the offset guideplates come in I believe a .150" offset to straighten up the rocker arm side to side geometry. You can run self aligning rocker arms, or install the correct guideplates, you can't run both, However, I have issue with the pushrods as well. A couple of things to take into account here. I know it's been said that the "contact" patch has been checked, but if it was checked with anything but a solid lifter, I can assure you just by looking at your pictures that the pushrods are most certainly the incorrect length for your application. Once you go adding aftermarket heads with a generally thicker deck/flange surface and most aftermarket heads run longer stemmed valves, and then you start decking the block and adding different thickness head gaskets and installing a roller cam and lifters suddenly the original valve train "geometry" is out of whack. I've seen cases where we've had to install pushrods as long as +1.100 to correct geometry issues on engines. Installing a roller camshaft and roller lifters generally can change the length of the pushrods sometimes by as much as a couple hundred thousands of an inch at a minimum, and then add back in thicker aftermarket heads, taller than stock valves, etc. it NEEDS to be checked and verified. And if it's being done with a hydraulic lifter in place of a solid lifter, you will NOT get a correct reading nor make a proper determination of push rod length. Throwing in +.100 length pushrods just because is asking for problems. I'm not saying you're going to have catastrophic failure, but you're valve train will be unstable at the very least. There are many variables involved and sometimes putting the correct parts in solves many other issues as well. For example, the rocker arms kissing the valve covers, even though those scorpions are a larger than most body. And when it comes to rocker arms, and valve tips, you generally want the rocker arm roller to "start" somewhat on the inboard third of the valve, and roll across the center of the valve stem as the lobe pushes the valve stem down (open) and end up somewhere on the outer third of the valve stem at max lift. Understand, that this is somewhat of a cliff notes version of checking geomtry, but getting it right now will keep you from having headaches in the future. I know I'm getting slightly off track here, but everything discussed in this thread needs to be checked. I'd be more concerned with proper geometry than I would the studs being .025 or so "out of round" although I agree that seems like quite excessive run out. Get em "squared" up first and then worry about the other stuff.

 

[MikeB]

I've had that problem on a few valves with Brodix IK heads and the Old Pro-Topline heads. I ended up using standard CompCams guide plates on the Pro-Toplines (which have pushrod guide holes in the head that I opened up just a little), and Isky adjustable plates on the Brodix heads.

Here's a shot of my initial problem with the Brodix IK 180 heads. You can see where the rocker is cocked slightly and the valves stem tip is very close to the rocker arm body. A problem just waiting to happen! As I recall it was the same 3 or 4 valves on each head. I don't have an "after" pic with the Isky adjustable plates.

Don't see why self-aligning rockers wouldn't work for you, assuming you can return or sell the ones you have.


As shipped with CompCams guide plates.

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Isky 200-AGP

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[Ronno6]

Thanks, QBuff02 for that input.
There is much there to digest.

I expect to correct the rocker arm alignment with self aligning rocker arms.

The studs are not "out of round" but, rather,not concentric: the axis of the top threads is not the same as that of the lower threads; studs remain perpendicular and parallel, just not on the same center line, and/or c to c dimensions may vary from pair to pair. This can result in pushrod ends of the rocker arms being closer or farther from the vertical wall of the valve cover, staggered, or closer together/farther apart than other pairs.

As for checking method, I am in a quandary. Hydraulic lifters receive a preload adjustment, which should be the dimension achieved when the lifter pumps up. Otherwise, if the lifter pumped up the remaining distance taken up by the 1/2 turn of preload (about .025" at the stud, greater at the lifter), the valve would never fully close. So, I suppose the lifter has some squish when the cam pushes it up. How much?? Dunno.
The pushrods which I purchased were the length specified by Comp Cams for my setup. I ordered nothing custom there.
As for the currently plotted course of action, I have ordered self aligning full roller rocker atms and have ground the slot ears off my guide plates. I also have ARP studs on the way. All should be showing up in 2 days. We'll see how things shake out then.

I am delving to this to the best of my ability, both pre-owned and newly acquired.
I cannot speak to any of this from a standpoint of experience, That is what I seek on forums such as these.
But, for the most part I do have reasonable logic skills which cause me to put way more thought into this stuff than I probably should.

As you obviously have a greater working knowledge in this area than I , I will consider your input carefully.
Thank you!

 

[Ronno6]

I've had that problem on a few valves with Brodix IK heads and the Old Pro-Topline heads. I ended up using standard CompCams guide plates on the Pro-Toplines (which have pushrod guide holes in the head that I opened up just a little), and Isky adjustable plates on the Brodix heads.

Here's a shot of my initial problem with the Brodix IK 180 heads. You can see where the rocker is cocked slightly and the valves stem tip is very close to the rocker arm body. A problem just waiting to happen! As I recall it was the same 3 or 4 valves on each head. I don't have an "after" pic with the Isky adjustable plates.

Don't see why self-aligning rockers wouldn't work for you, assuming you can return or sell the ones you have.


As shipped with CompCams guide plates.

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You must be registered for see images

Isky 200-AGP

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I ordered a wet of those guide plates, but failed to read the specs carefully. I received guides for 3/8" pushrods, not the 5/16 which 'I need. Those have been returned. I ground the tabs off my fixed guide plates in order to use them as washers/spacers. I should receive my self aligning rockers on Wednesday (in 2 days) along with the closer tolerance ARP studs. We shall see haw things go from there. The rockers also have a more traditionally shaped rounded push rod end which should alleviate my valve cover interference problem.

 

[QBuff02]

To try and clarify a few things, I know when looking at the alignment one would think that everything needs to be the "same" from top to bottom. but i'll use a big block chevy for example. If you look at the valvetrain geometry, the push rods do not run straight up and down from lifter to rocker arm, due to the canted nature of the valves. however, the guide plates keep everything in "line". basically, if the push rod is seated in the pocket of the lifter and it's also seated in the pocket of the rocker arm, the pushrod will not go anywhere and then you have the guideplates to make sure that everything stays "in line" if that makes sense? So in theory if you have a guide plate that is more in line with the lifter and the rocker arm (offset) then the rocker arm will run more true to the valve stem. When you put pressure on the rocker arm as you "set" the valves things will try to find their natural location. Even if the geometry is off by a few .100. but if the plates are too wide or narrow, it creates a situation similar to what you're experiencing. So in theory, offset or adjustable guideplates or modifying the ones actually on the head wider/narrower (which was an old speed trick before the advent of adjustable plates was something a lot of people did. (before my time by the way) Also, make sure you're running a hardened plate and or pushrods to avoid wear as the engine runs. I believe you already have hardened pushrods by the number. But in doing all of this you have to make sure there is enough clearance where the push rod goes through the head as you do not want the push rods binding as they move. Another thing on the pushrods is, most maunfacturers "recommend" parts and pieces based on stock parts being used. I.E. stock block and head configuration, so if you install a retrofit roller cam into an old 350 block and use stock heads, they know that "this length" of push rod should be the one you need. because they know that a stock length pushrod is 7.800 (I looked it up because I couldn't remember exactly) and when you install roller cam and lifters you lose something along the lines of .400 or more in length on the pushrod due to the taller design of a roller lifter. but then when you add aftermarket heads with different thickness than stock and valves that don't have original length, things will start to grow or shrink accordingly. I'd bet you'd need a push rod in the 7.300-7.400 length if I was to guess. Just went through something similar on a 355 I built last fall and we ended up with 7.450 push rods.
Anywho, years ago I asked the same question as you to my boss at the time about how setting the valves with a solid lifter vs a hydraulic lifter mattered and why the valve doesn't hang open once there's oil pressure in the engine.. You want to use a solid lifter to check things because you need the valve train as stable as possible for one, and if you're checking clearances with a hyd lifter in place, you can be off by as much as something like .100 if you happen to depress the lifter plunger to the bottom of the "seat" if that makes sense? as far as setting preload and the valves not sticking open.. Most springs have somewhere along the lines of at least 105+lbs of seat pressure (usually 125+ on anything set up for performance depending on camshaft) at a minimum and most engines have -80lbs of oil pressure at maximum. So even though you've got good oil pressure you don't have enough to overcome the seat pressure of the closed valve, hence the valve won't "hang" open. A hydraulic lifters nature is such that once the cam lobe starts raising it off the seat the oil passage to the lifter becomes blocked basically turning it into a "solid" lifter while it's in motion but as it sets back down on the heel of the cam lobe the passage opens back up and acts like a cushion. long story short anyway. Lol Gotta run today, but hope some of this helps make things make sense..