Aluminum Rocker Arm Material Specification?

Posted By: YO7_A66

Aluminum Rocker Arm Material Specification? - 06/17/13 07:07 PM

What series aluminum do the major rocker arm manufacturers use on the Mopar rocker arms?
I read that Dove specifies "7000" series aluminum (on their web sight) for their rockers.

EDIT:
* Harland Sharp / Hughes = 2024-T3511 extrusions (REF: tensile = 68ksi, yield = 41ksi)
* Dove = 7000 (REF: tensile = 58ksi, yield = 52ksi)
The HS/Hughes and the Dove average out (T/Y)to be right at the same ratings.

What material are the others using that you know of? (Comp, Crane, HS, etc.)

What series of aluminum do I stay away from when purchasing?

This coming Fall I will be in the market to buy a set of the aluminum rockers and I am just doing my homework.

Thanks

Posted By: dogdays

Re: Aluminum Rocker Arm Material Specification? - 06/17/13 07:50 PM

Most aluminum rocker arm manufacturers do not publicize their alloys.

IMHO, it's not the alloy you should look out for, it's the designer/manufacturer. There are good and bad, and too often the bad ones are the inexpensive ones.

R.

Posted By: YO7_A66

Re: Aluminum Rocker Arm Material Specification? - 06/18/13 05:03 PM

Thanks for the info Dog.

While I was searching for more material specs, I came across this link to a Hot Rod rocker arm comparison. This has allot of great info.!!

http://www.hotrod.com/techarticles/engine/hrdp_1305_rocker_arm_comparo/viewall.html

Posted By: dogdays

Re: Aluminum Rocker Arm Material Specification? - 06/18/13 05:54 PM

Yes, I have that issue at home.

As a mechanical designer, I have to say a few things:
1. Everything depends on the design. The designer makes the design, figures out the material needs, and specifies a material that meets the needs. Better designers make better design choices.
2. As someone is likely to point out, EVERY aluminum alloy has a fatigue life and at SOME number of cycles, the strength will fall below the requirement of the part and it will fail. Now, there is still a lot of discussion about what constitutes a cycle. Facts are, aluminum pistons seem to last indefinitely. Aluminum rocker arms (the good ones) rarely fail, and when they do, it's usually a failure precipitated by another cause than fatigue.
3. It is possible to use a really good material and with a bad design, have failures.
4. It is possible to have a good design and good material, but because of bad manufacturing processes, have failures.
5. It is possible to have good design, material, AND manufacturing processes and have the failure because of a wrong application.

Conclusion: While, on the surface, material seems to play a big role, the sum total of design, material, manufacturing process and application determines whether the part will work and survive, or not.

R.

Posted By: 5spdcuda

Re: Aluminum Rocker Arm Material Specification? - 06/18/13 07:42 PM

Dogdays points are well taken. As to your specific question regarding material, I had an interesting [ to me anyway ] conversation this morning with a representative of Dove manufacturing. He was unable to confirm outright that Indy rockers are made by Dove but he did say that he was very familiar with Indy's rockers and that they were definitely made of 7100 series aluminum alloy. I am not a metallurgist, but I do know that the primary alloying element in 7000 series is zinc and that it has the highest tensil stength of all aluminum alloys [ in excess of 70,000 psi when heat treated ] and is used extensively in the aircraft industry for structrual components. It is also used by Smith & Wesson for aluminum framed handguns. 2024 As used by Harlan Sharp is also a very strong alloy [ copper being the primary alloying element ] and is also used by the aircraft industry. In short keeping in mind Dog's admonition regarding design, heat treated 7000 series is as good a material as we are likely to find in an aluminum rocker.

Posted By: JohnRR

Re: Aluminum Rocker Arm Material Specification? - 06/18/13 09:45 PM

Quote:

What series aluminum do the major rocker arm manufacturers use on the Mopar rocker arms?
I read that Dove specifies "7000" series aluminum (on their web sight) for their rockers.

EDIT:
* Harland Sharp / Hughes = 2024-T3511 extrusions (REF: tensile = 68ksi, yield = 41ksi)
* Dove = 7000 (REF: tensile = 58ksi, yield = 52ksi)
The HS/Hughes and the Dove average out (T/Y)to be right at the same ratings.

What material are the others using that you know of? (Comp, Crane, HS, etc.)

What series of aluminum do I stay away from when purchasing?

This coming Fall I will be in the market to buy a set of the aluminum rockers and I am just doing my homework.

Thanks

I would stay away from alum all together, if you must buy an alum rocker make sure it has these 2 properties ..

It is has a bronze bushing where it rides on the shaft

AND

Itt's not an offshore piece of crap .

I'd buy Comp pro magnums ...

Posted By: nomore65BelvJim

Re: Aluminum Rocker Arm Material Specification? - 06/26/13 06:20 AM

Quote:

I would stay away from alum all together

Unless there isnt another option available I'd never use aluminum rockers on a street car, again.

Posted By: goldmember

Re: Aluminum Rocker Arm Material Specification? - 06/26/13 06:38 AM

Quote:

Quote:

What series aluminum do the major rocker arm manufacturers use on the Mopar rocker arms?
I read that Dove specifies "7000" series aluminum (on their web sight) for their rockers.

EDIT:
* Harland Sharp / Hughes = 2024-T3511 extrusions (REF: tensile = 68ksi, yield = 41ksi)
* Dove = 7000 (REF: tensile = 58ksi, yield = 52ksi)
The HS/Hughes and the Dove average out (T/Y)to be right at the same ratings.

What material are the others using that you know of? (Comp, Crane, HS, etc.)

What series of aluminum do I stay away from when purchasing?

This coming Fall I will be in the market to buy a set of the aluminum rockers and I am just doing my homework.

Thanks

I would stay away from alum all together, if you must buy an alum rocker make sure it has these 2 properties ..

It is has a bronze bushing where it rides on the shaft

AND

Itt's not an offshore piece of crap .

I'd buy Comp pro magnums ...

I kinda agree. For the mild combo you list the only benefit is weight loss( a few ounces?Not likely)) and nothing more,no slight rocker ratio change will net a hp increase that is measurable. Lot's of $$$$ spent to likely have less reliability in the long run for such a mild street build. I do agree that if you must put any aftermarket rocker on it don't waste time with any cheap units.

Posted By: YO7_A66

Re: Aluminum Rocker Arm Material Specification? - 06/26/13 12:33 PM

I want a steel roller rocker arm, but I am having trouble finding one with a 1.6 ratio. I think that I found a set from Crane, but the price seemed to be too good to be true. So I have been looking at the aluminum kits.
I am mainly looking to upgrade now in the case that I have engine work done in the future. If I can budget the rocker arms now, then that would already be taken care of down the road if I have any head work done.
Does anyone know of a "good" steel set (kit) of 1.6's for a sb? Comp only had the 1.5's that I could find.

Thanks

Posted By: jcc

Re: Aluminum Rocker Arm Material Specification? - 06/26/13 02:07 PM

Quote:

Dogdays points are well taken. As to your specific question regarding material, I had an interesting [ to me anyway ] conversation this morning with a representative of Dove manufacturing. He was unable to confirm outright that Indy rockers are made by Dove but he did say that he was very familiar with Indy's rockers and that they were definitely made of 7100 series aluminum alloy. I am not a metallurgist, but I do know that the primary alloying element in 7000 series is zinc and that it has the highest tensil stength of all aluminum alloys [ in excess of 70,000 psi when heat treated ] and is used extensively in the aircraft industry for structrual components. It is also used by Smith & Wesson for aluminum framed handguns. 2024 As used by Harlan Sharp is also a very strong alloy [ copper being the primary alloying element ] and is also used by the aircraft industry. In short keeping in mind Dog's admonition regarding design, heat treated 7000 series is as good a material as we are likely to find in an aluminum rocker.

However one factor left out of this discussion is operating temp, and we all know that around 400F, alum has lost a lot of strength, but each alloy has a different heat curve, and that is tougher to decipher for each application. For any street/endurance application, alum rockers offer few advantages compared to the tradeoffs, IMO