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The high tech stainless are sweet, although you really cannot go wrong with any Comp Cams full roller rocker. Ratio depends on cam, clearance, valve springs, etc.
 

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copasspupil said:
I just got off the phone with AFR crane gold or comp cam 1.6 aluminum or stainless. FYI, Comp cam pro magnum still seem to float per AFR.
Dan - please expand on this. I've had the pro magnums on there since I put the AFR's on and aside from finding them a bit chatty haven't had any issues with them through 6500. Just curious what AFR has to say (since they originally recommended the Pro Magnums!).
 

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Discussion Starter · #7 ·
They said that they have had issues with the weight of the pro magnums. Apparently, the mag's still causing floating even with the upgraded/stiffer springs. My guess is that customers had issues so they have made different suggestions.

Initially, they said only Crane's gold. I ask about comp cams line of roller rockers. They then said to only go with aluminum or stainless and not the pro mag's.
 

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i used scorpion 1.6 rollers on my afr 165's. also upgraded the springs to beehives...
 

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I don't have any definitive answers to the questions raised in this thread. I did not get the same answers that Copass is getting, when I installed a set of AFR's.

First off, don't forget that your cam profile and rpm range are huge variables that contribute to valve float. You might be okay with the valves, retainers, and springs that come with the AFR heads, depending on your cam and rpm range.

When I purchased my AFR 205's and custom cam, I knew what I was building the engine for, and that affected my choices for several parts. I verified my choices with two folks that I trust: My cam builder, and a guy named Alex (aka, MoneyMaker).

Here is one exchange I had with the cam builder, who was also assembling my AFR heads:
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randy: Can you be more specific about "Lightweight valvetrain components are mandatory?" Is that above and beyond the titaniam retainers you suggest for the heads?

cam builder: Ti retainers are perfect. The valves I use in the bigger AFR heads are also fine for this usage.

randy: Do you consider Comp/Crane solid roller lifters heavy weight?

cam builder: Weight at that end of the valvetrain is not as important as at the valve side. Use the strongest lifers available.

randy: Am I looking at an additional $600-$700 for super-light lifters, rockers, etc?

cam builder: A better rocker is a good investment but going nutty on lifters and rockers is not practical for this application.
---------------------------------------------

Another thing you need to consider is the clearance between the rocker and the valve spring retainer. I don't know if there is a difference in the spring diameter between the AFR 185's and the 205's, but clearance was a factor in my choice of rockers.

My target was max Torque in the 2500-6600 rpm range. In the end, I had this setup on my heads and valve train:
Comp Magnum rockers
Comp Cams Endura-X Solid Roller Lifters
Titanium Spring Retainers
Cam builder's choice of valves and springs

Just another opinion,
randy
 

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From what I've read, stainless is stronger and smaller. One reason why aluminum ones are bigger in comparison to stainless is that they must be built a little bigger for strength. If I had the money I would've bought stainless.

In my choice, I had read endless accounts of Crane Gold and Scorpions. I used the scorpion 1.72 aluminum to get just a little extra lift and because I had the clearance for them. They're a smidge cheaper than Crane Gold's too.

Chaz
 

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planomustang said:
randy: Do you consider Comp/Crane solid roller lifters heavy weight?

cam builder: Weight at that end of the valvetrain is not as important as at the valve side. Use the strongest lifers available.
It's a puzzling statement to say that the mass of the lifter is not important but the masses of the valve and the retainer are. All the valve train mass is put in motion by the same force: the rotation of the cam lobe. All that mass is controlled by the same resistance to force: the spring(s).

I guess one difference is the effect of leverage about the rocker fulcrum. For example, a 1.6:1 rocker will give a 1.6 force multiplier to the mass of the valve-spring-retainer-keeper assembly, compared to a 1.0 multiplier for the lifter-pushrod assembly. So a gram saved on the valve side has 1.6 times the benefit of a gram saved on the lifter side. But that doesn't mean that weight loss on the lifter side produces no benefit, just that weight loss on the valve side produces more. And because a lifter, particularly a roller lifter, is the most massive component of the valve train, there is more room for improvement there than at the retainer or the valve.

About choice of rockers: I'm putting Crane High Energy rockers in the 302 I'm putting together. David Vizard of Popular Hot Rodding wrote that their configuration provides a quicker opening than any other design. They're diecast aluminum, so they're not the strongest, but at $180 (Summit) they're not the most expensive either. They also have a Ford logo and a Ford part number on them, which I interpret as an indicator of durability. They're also a simple bolt on for a pedestal mount head, and I've checked the geometry with stock 6.25" roller cam pushrods and a sub 0.500" lift cam and there are no worries.
 

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180 Out said:
It's a puzzling statement to say that the mass of the lifter is not important but the masses of the valve and the retainer are. All the valve train mass is put in motion by the same force: the rotation of the cam lobe. All that mass is controlled by the same resistance to force: the spring(s).
180 Out - I never thought about the affect different rocker ratios would have on valve float. Now take that thought to the next step. With a 1.7 ratio rocker, the spring has a mechanical advantage when it pushes the lifter down, right? So removing a gram from the lifter does not have nearly the positive affect as removing a gram from the valve assembly.

My un-professional take on valve-float was that the springs are not able to close the valve, and a gap actually forms between the rocker and the valve tip. In other words, the spring is effectively decoupled from the rocker and lifter assembly. So my conclusion is that valve side wieght is more important to reduce valve float

Another unprofessional opinion ;)
randy
 

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planomustang said:
180 Out said:
It's a puzzling statement to say that the mass of the lifter is not important but the masses of the valve and the retainer are. All the valve train mass is put in motion by the same force: the rotation of the cam lobe. All that mass is controlled by the same resistance to force: the spring(s).
180 Out - I never thought about the affect different rocker ratios would have on valve float. Now take that thought to the next step. With a 1.7 ratio rocker, the spring has a mechanical advantage when it pushes the lifter down, right? So removing a gram from the lifter does not have nearly the positive affect as removing a gram from the valve assembly.

My un-professional take on valve-float was that the springs are not able to close the valve, and a gap actually forms between the rocker and the valve tip. In other words, the spring is effectively decoupled from the rocker and lifter assembly. So my conclusion is that valve side wieght is more important to reduce valve float

Another unprofessional opinion ;)
randy
I think that rocker mass would be fairly inconsequential to valve train stability, because all that mass is so close to the pivot point. It's similar to how an imbalance near the hub of a road wheel is unimportant, but the same imbalance at the rim will be a bad thing.

I think that valve bounce is more of a problem, and more of an rpm limiter, than valve float. I agree, my understanding of valve float is that the mass of the valve train overcomes the ability of the spring to control all the clearances -- cam to lifter, lifter to pushrod, pushrod to rocker, and rocker to valve -- and gaps open up. However, this is not that much of a problem; in fact Super Stockers deliberately set up their engines to launch the lifter off the cam lobe, to get more lift than the rules allow with respect to the cam lobe itself. But valve bounce is always bad. By definition, valve bounce happens after the intake closing, which generally occurs about 15-25 crank degrees into the compression stroke. With the valve bouncing off the seat, the fuel air mixture is pushed out the intake and dynamic compression is lost. Both of these events reduce cylinder pressure on the power stroke, and this is why most valve trains hit the wall of peak rpm.

Anyway, valve bounce is also caused by valve train mass, specifically the inability of the spring to control the valve.

Come to think of it, this probably answers my first question, of why valve and retainer mass is more important than lifter and pushrod mass, when you're looking for bang for the buck -- that valve bounce is such a bad thing, and it is minimized mostly with weight loss at the valve side, not the lifter side.
 

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copasspupil said:
They said that they have had issues with the weight of the pro magnums. Apparently, the mag's still causing floating even with the upgraded/stiffer springs. My guess is that customers had issues so they have made different suggestions.

Initially, they said only Crane's gold. I ask about comp cams line of roller rockers. They then said to only go with aluminum or stainless and not the pro mag's.

Me thinks AFR is covering their collective butts on this one. I fail to see how the mass of the rocker has anything to do at all with valve float.

The weight of the rocker, even dynamically at high RPM is trivial in comparison to the reaction force of the compressed spring.
 

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Discussion Starter · #19 ·
I just got off the phone with comp cams and they said that if anything the pro mag's are lighter than aluminum but will last longer since they can be rebuilt. No significant hp gain with one over the other. They had never heard what AFR had said about their products before with.

I'm going with pro mag's and they too recommended their stud girdle.
 
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