Rocker geometry...my turn - Page 3 - Chevelle Tech
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post #31 of 55 (permalink) Old Mar 25th, 20, 10:52 AM Thread Starter
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Re: Rocker geometry...my turn

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Originally Posted by shovelrick View Post
This is how mine came out with Straub INT. rockers on all valves, I'm very happy and also like these Trend perf. PRs I still need to put #1 springs back on and adjust them, this is with Howards (Gatorman) max effort lifters
Looks good Rick. Does the motor your building go into the taxi cab?

I ordered rockers from Chris for just the intake because my exhaust rockers look pretty good. One problem is that I'll have 1/2 blue and 1/2 bare aluminum. I really like the blue rockers, but that's just the way it is...bummer. Those Scorpion rockers are brand new, and I really don't want to fix something that isn't broken. Or should I say broken yet...PIMA has a way of breaking things...
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post #32 of 55 (permalink) Old Mar 25th, 20, 11:04 AM
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Re: Rocker geometry...my turn

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Originally Posted by kimosabi View Post
That video is all about centering the sweep on the valve stem and not about correct push rod length.

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post #33 of 55 (permalink) Old Mar 25th, 20, 11:28 AM
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Re: Rocker geometry...my turn

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doesn't seem that complex to me, if the BBC head comes with a valve and spring setup for .600" lift they need to tilt the rocker stud to fit a 1.65" rocker correctly, I can't visualize what problem that change would generate, they all need specific length pushrods and stud girdles anyway, actually moving the stud say .050" might cause some interference issue somewhere but changing the angle seems doable to me
I didn't even consider the head manufacture changing the rocker stud angle. Like SteelComp said, they need to converge with the valve angles. I thought the question by Roadknee was more along the lines of changing the location of the rocker studs rather than changing the angle of them.

But do you really think that any head manufacture is going to use either a different angle or a different rocker stud location for every single customer and for every possible combination of rocker arm and lift range used? You used an example of .600" lift, but who's to say what's average, or even what lift the majority of customers are using in light of the multitude of camshaft choices there are out there? I mean assuming a .600" lift at the valve for most customers, (which is relatively very mild by today's standards in BBC builds even for pump gas street cars) would be like assuming that most guys who are willing to spend $3K on cylinder heads for their street/strip pump gas cars, aren't also willing to reach for some big power and bigger lift from a roller cam to take full advantage of that $3K that they just dropped on the new heads.

The point being, (again) that there isn't any specific standard when it comes tocam lift anymore. It isn't like back in the day when most guys just went to the parts department at their local Chevy dealer, and ordered either an L-88 camshaft, or a ZL-1 camshaft, because there wasn't a whole lot else to choose from in the way of ultimate street performance.

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post #34 of 55 (permalink) Old Mar 25th, 20, 12:55 PM Thread Starter
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Re: Rocker geometry...my turn

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Originally Posted by BillyGman View Post
But do you really think that any head manufacture is going to use either a different angle or a different rocker stud location for every single customer and for every possible combination of rocker arm and lift range used?
The answer is NO. Another definition of "custom" is "wrong" or "make it fit".

The thing that really pi$$es me off is that they can't even get their manufacturing right on pushrod guides. Some of the rockers where hanging off of the valve tip when I first put my engine together. I had to get adjustable guides to center them. The AFR person that I talked to said to whack them in half and weld them back together. WHY?!?! I paid decent money for these AFR heads! Centering the pushrod should be in one spot, or if it isn't, send them with adjustable guides instead of ones that are wrong. The AFR person also told me that I should use headers with 2 1/8 primaries, so I have my $2K Lemons to help with all of the header problems that I've had with my 2" Headman's. Burning plug wires, blowing gaskets, and smashing tubes to get them to even fit. Oh well. I digress...

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Engine parts: (Heads, cam & lifters from Lewis Racing Engines)
ZZ502 Short block
AFR 305 CNC 106cc Chambers 8002 springs
Bullet HR ADV Dur 295/297 238/242 @ .050 .680/.650-110 LSA-108 ICL Morel lifters
Holley Avenger MPFI
612HP/594TQ
T-56 Magnum trans with hydraulic McLeod RST
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post #35 of 55 (permalink) Old Mar 25th, 20, 3:55 PM
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Re: Rocker geometry...my turn

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Originally Posted by MarkP View Post
The answer is NO. Another definition of "custom" is "wrong" or "make it fit".

The thing that really pi$$es me off is that they can't even get their manufacturing right on pushrod guides. Some of the rockers where hanging off of the valve tip when I first put my engine together. I had to get adjustable guides to center them. The AFR person that I talked to said to whack them in half and weld them back together. WHY?!?! I paid decent money for these AFR heads! Centering the pushrod should be in one spot, or if it isn't, send them with adjustable guides instead of ones that are wrong. The AFR person also told me that I should use headers with 2 1/8 primaries, so I have my $2K Lemons to help with all of the header problems that I've had with my 2" Headman's. Burning plug wires, blowing gaskets, and smashing tubes to get them to even fit. Oh well. I digress...
We used to have to cut and weld stock GM guide plates on certain heads. Been common practice since the beginning of all this stuff. I think some of you guys expect a little too much. Now, bad advice form a manufacturer...that's NEVER been a problem.
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post #36 of 55 (permalink) Old Mar 25th, 20, 5:22 PM Thread Starter
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Re: Rocker geometry...my turn

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Now, bad advice form a manufacturer...that's NEVER been a problem.
Don't you manufacture engines, Scott?

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Engine parts: (Heads, cam & lifters from Lewis Racing Engines)
ZZ502 Short block
AFR 305 CNC 106cc Chambers 8002 springs
Bullet HR ADV Dur 295/297 238/242 @ .050 .680/.650-110 LSA-108 ICL Morel lifters
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post #37 of 55 (permalink) Old Mar 25th, 20, 7:00 PM
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Re: Rocker geometry...my turn

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Originally Posted by MarkP View Post
The answer is NO. Another definition of "custom" is "wrong" or "make it fit".

The thing that really pi$$es me off is that they can't even get their manufacturing right on pushrod guides. Some of the rockers where hanging off of the valve tip when I first put my engine together. I had to get adjustable guides to center them. The AFR person that I talked to said to whack them in half and weld them back together. WHY?!?! I paid decent money for these AFR heads! Centering the pushrod should be in one spot, or if it isn't, send them with adjustable guides instead of ones that are wrong. The AFR person also told me that I should use headers with 2 1/8 primaries, so I have my $2K Lemons to help with all of the header problems that I've had with my 2" Headman's. Burning plug wires, blowing gaskets, and smashing tubes to get them to even fit. Oh well. I digress...
Well I don't remember any head manufacture actually claiming that their heads are "custom" and frankly, I don't view them as such. There are just too many variables and too many possible combinations for a head company to relocate the rocker stud holes for every single customer. That would be impossible.

Now in the case of pushrod guides, I don't blame you for having sour grapes about that. That sounds like it's merely poor overseas manufacturing processes. And the header thing is a whole other ball of wax all together. Especially with the steering shaft of GM A-body cars like ours being right smack in the way of the #3 and #5 cylinder primary tubes. Having a Chevelle with a tall deck block and raised exhaust ports on the heads, I know that whole scenario all too well.

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post #38 of 55 (permalink) Old Mar 25th, 20, 9:35 PM
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Re: Rocker geometry...my turn

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Originally Posted by BillyGman View Post
I didn't even consider the head manufacture changing the rocker stud angle. Like SteelComp said, they need to converge with the valve angles. I thought the question by Roadknee was more along the lines of changing the location of the rocker studs rather than changing the angle of them.

But do you really think that any head manufacture is going to use either a different angle or a different rocker stud location for every single customer and for every possible combination of rocker arm and lift range used? You used an example of .600" lift, but who's to say what's average, or even what lift the majority of customers are using in light of the multitude of camshaft choices there are out there? I mean assuming a .600" lift at the valve for most customers, (which is relatively very mild by today's standards in BBC builds even for pump gas street cars) would be like assuming that most guys who are willing to spend $3K on cylinder heads for their street/strip pump gas cars, aren't also willing to reach for some big power and bigger lift from a roller cam to take full advantage of that $3K that they just dropped on the new heads.
Yes, I was referring to moving the whole rocker toward the intake and leaving the angle the same. I understand the available rockers would probably all leave a pattern in a slightly different place, but at least it would be closer to center. I wonder if AFR overlooked this or simply wasn’t concerned with a pattern 0.030 or 0.040” from the edge of the valve.
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post #39 of 55 (permalink) Old Mar 25th, 20, 10:39 PM
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Re: Rocker geometry...my turn

This is a BIG trial and error on what works and don't work, I'm just glad this isn't holding up a daily driver, I'm very happy with what I have now, THANKS Scott & Chris for working with me on the swap, IMO for a street maybe some strip car .600 lift with decent duration should be plenty


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post #40 of 55 (permalink) Old Mar 25th, 20, 11:59 PM
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Re: Rocker geometry...my turn

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Originally Posted by Roadknee View Post
Yes, I was referring to moving the whole rocker toward the intake and leaving the angle the same. I understand the available rockers would probably all leave a pattern in a slightly different place, but at least it would be closer to center. I wonder if AFR overlooked this or simply wasn’t concerned with a pattern 0.030 or 0.040” from the edge of the valve.
There's more than one way to look at it. For instance, maybe it's the rocker arm companies dropping the ball. But in general, this is how it is with aftermarket parts. As far as I know, the cylinder head companies put the rocker stud holes in the BBC stock locations. Like I said, it's the higher lift cams, longer valves, and taller valve springs that are required with the bigger lift that begin to change things.
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post #41 of 55 (permalink) Old Mar 26th, 20, 8:03 AM
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Re: Rocker geometry...my turn

My earlier post I should have said it's more trial and error for a person like myself that's just learning this Billy I think that's exactly what it is, when you raise two parts that aren't parallel to each other the distance is going to change the further you go if that makes any sense, I had that problem with PRs on a stroked shovelhead 20yrs. ago and bent a bunch of PRs until I found Crane adj. PRs made for my stroker (taller and made the V twin farther apart) engine


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post #42 of 55 (permalink) Old Mar 26th, 20, 10:34 AM
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Re: Rocker geometry...my turn

Quote:
Originally Posted by Roadknee View Post
Yes, I was referring to moving the whole rocker toward the intake and leaving the angle the same. I understand the available rockers would probably all leave a pattern in a slightly different place, but at least it would be closer to center. I wonder if AFR overlooked this or simply wasn’t concerned with a pattern 0.030 or 0.040” from the edge of the valve.
AFR has moved their rocker studs and valves several times. This is why we're on V2 of their heads. AFR is not going to make their heads based on available rocker arms. That's just silly. There are a lot of factors that go into where a rocker stud goes, especially with canted valves. It's not just arbitrary. One major problem is the pushrod side of the rocker and it's proximity to the valve cover. Not very much wiggle room there at all so you can't just decide to move the rocker away from the valve without causing other problems. The easiest solution is what I did and that's to come up with a rocker that fits the application. When you're trying to do things with a cylinder head that it was never designed to do, you run into these things.
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post #43 of 55 (permalink) Old Mar 26th, 20, 10:37 AM
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Re: Rocker geometry...my turn

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Originally Posted by BillyGman View Post
There's more than one way to look at it. For instance, maybe it's the rocker arm companies dropping the ball. But in general, this is how it is with aftermarket parts. As far as I know, the cylinder head companies put the rocker stud holes in the BBC stock locations. Like I said, it's the higher lift cams, longer valves, and taller valve springs that are required with the bigger lift that begin to change things.
AFR's valves and rocker studs aren't in the stock location. You can not use a factory BB Chev stud girdle on AFR's and you can't use an early "S" version AFR stud girdle on a V2.
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post #44 of 55 (permalink) Old Mar 26th, 20, 1:29 PM
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Re: Rocker geometry...my turn

Just a bit off topic.
A trick that I have been using for long time in regards to adjusting valves that use poly locks.
Once you have concluded that your valves are adjusted correctly and your rocker arm poly locks have been cinched down with the locking Allen - you take a depth mic or a vernier caliper. Measure from the top of the poly lock down to the inside of the locking nut and record this measurement for that valve. Continue this way until all your depths have been measured. You shouldn’t be surprised how very close they are. The engines I’ve done are usually all within .005” and some are within your own variable in measure. .001” or .002”.
Now... if you ever have to take the rocker off for any reason you can quickly get back to how it was set originally by just going back to that same measurement. Doesn’t matter where the cam is. Works every time!
This has saved me from cycling thru valve events many times - track included.
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post #45 of 55 (permalink) Old Mar 26th, 20, 1:37 PM
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Bradley 67. Yep good tip I do same thing with my shaft rocker adjusters

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