What the difference between Aluminum Roller rockers
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Joined: Jan 2001
Posts: 691
From: Jacksonville, FL
What the difference between Aluminum Roller rockers
What’s the big difference between the aluminum roller rockers?
I understand the difference between the cast & billet ones (I understand that the billet will take more spring abuses/full out racing etc) self and non ailing but after flipping through the Summit catalog I see a vast price difference between a summit cast rocker and a crane etc
For example is there a real big difference between a GM hot cam roller rockers then the crane cam gold racer rockers?
is there a big difference between the cheaper rollers (quality/ friction etc.)
Also what's the best way to convert to non-ailing rockers
thanks
I understand the difference between the cast & billet ones (I understand that the billet will take more spring abuses/full out racing etc) self and non ailing but after flipping through the Summit catalog I see a vast price difference between a summit cast rocker and a crane etc
For example is there a real big difference between a GM hot cam roller rockers then the crane cam gold racer rockers?
is there a big difference between the cheaper rollers (quality/ friction etc.)
Also what's the best way to convert to non-ailing rockers
thanks
Last edited by Maldo; Mar 12, 2004 at 03:33 PM.
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Joined: Oct 2002
Posts: 2,931
From: Upstate NY
Re: What the difference between Aluminum Roller rockers
Originally posted by Maldo
What’s the big difference between the aluminum roller rockers?
Grade of aluminum and heat treatment mostly.
7000 series Aluminum (7075 for example) heat treated to T6 condition is about the strongest aluminum. 6000 series is less strong, but not often used for rocker arms. The 8560 alloy steel investment cast ones are about 3 times as strong as 7075.
15-5 PH stainless steel, also investment cast, is the next step up.
I understand the difference between the cast & billet ones (I understand that the billet will take more spring abuses/full out racing etc) self and non ailing but after flipping through the Summit catalog I see a vast price difference between a summit cast rocker and a crane etc
For example is there a real big difference between a GM hot cam roller rockers then the crane cam gold racer rockers?
is there a big difference between the cheaper rollers (quality/ friction etc.)
Most aluminum rockers are machined from an extrusion which has the basic sideview shape of the rocker. Imagine slicing off 1 inwide slugs then machining the holes, slots, etc. That's as close to "billet" (made from bar of stock) as aluminum rocker arms get. I don't recall any aftermarket diecast arms. High density pressure casting can be used on OEM, but the tooling is too expensive for aftermarket.
Other things that make rockers cheaper or more expensive are the steel pieces. The rollers and shafts in high quality (high $) ones are 8620 (Nickel-Chrome-Moly) bearing steel. Heat treating it is not cheap, but it's tough with a hard outer surface. Cheaper steels/processes could be used.
You pretty much get what you pay for in rockers. You should match the rockers to the demands of the valvetrain: high rpm, aggressive cam lobes, and the resulting stiff springs demand very stiff rocker arms, along with pushrods. Lightweight valves and retainers help keep the loads down. (F=Ma) That's why titanium is so popular in spite of its expense.
Also what's the best way to convert to non-ailing rockers
thanks
Use non-aliging rockers and the correct pushrod guide plates with your hardened pushrods.
What’s the big difference between the aluminum roller rockers?
Grade of aluminum and heat treatment mostly.
7000 series Aluminum (7075 for example) heat treated to T6 condition is about the strongest aluminum. 6000 series is less strong, but not often used for rocker arms. The 8560 alloy steel investment cast ones are about 3 times as strong as 7075.
15-5 PH stainless steel, also investment cast, is the next step up.
I understand the difference between the cast & billet ones (I understand that the billet will take more spring abuses/full out racing etc) self and non ailing but after flipping through the Summit catalog I see a vast price difference between a summit cast rocker and a crane etc
For example is there a real big difference between a GM hot cam roller rockers then the crane cam gold racer rockers?
is there a big difference between the cheaper rollers (quality/ friction etc.)
Most aluminum rockers are machined from an extrusion which has the basic sideview shape of the rocker. Imagine slicing off 1 inwide slugs then machining the holes, slots, etc. That's as close to "billet" (made from bar of stock) as aluminum rocker arms get. I don't recall any aftermarket diecast arms. High density pressure casting can be used on OEM, but the tooling is too expensive for aftermarket.
Other things that make rockers cheaper or more expensive are the steel pieces. The rollers and shafts in high quality (high $) ones are 8620 (Nickel-Chrome-Moly) bearing steel. Heat treating it is not cheap, but it's tough with a hard outer surface. Cheaper steels/processes could be used.
You pretty much get what you pay for in rockers. You should match the rockers to the demands of the valvetrain: high rpm, aggressive cam lobes, and the resulting stiff springs demand very stiff rocker arms, along with pushrods. Lightweight valves and retainers help keep the loads down. (F=Ma) That's why titanium is so popular in spite of its expense.
Also what's the best way to convert to non-ailing rockers
thanks
Use non-aliging rockers and the correct pushrod guide plates with your hardened pushrods.
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Joined: Mar 2000
Posts: 2,037
From: 51°N 114°W, 3500' elevation
I broke a trunion in a Crane Gold a few years ago when I blew up an engine. I had some spare Crane Energizers which look identical except they are a silver color. I pressed out the trunion in each and even though the rockers looked the same, the trunion in the Gold was thicker. The external dimension was the same and the hole for the rocker stud was the same but you could physically see that the gold's trunion was stronger. Fully assembled you couldn't see any difference between the 2 different rockers.
I now use Comp Pro Magnum stainless rockers and have put them through a lot of abuse.
If you're going to buy an aluminum rocker, stay away from the cast ones. The billet ones are not much more expensive and much stronger.
I now use Comp Pro Magnum stainless rockers and have put them through a lot of abuse.
If you're going to buy an aluminum rocker, stay away from the cast ones. The billet ones are not much more expensive and much stronger.
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Joined: Dec 1999
Posts: 1,697
From: Petersham, MA
I've gotta agree with the Comp Pro Magnum 8650 chromemoly steel roller rockers. I have a set, and they are way beefier than my buddys Crane Golds. Plus they are rebuildable. No way I ever buy aluminum rockers as long as the Comp is making the Pro Magnums.
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