opinions on roller rockers

[John Dol]

There are many different roller rockers; aluminum, steel and stainless. What would you recommend for a street car.
I'm going to need 1.6 3/8 studded mount.

Thanks,

John

[michael everson]

Ford racing uses Crane aluminum rockers on there Mustang Cobra engines. I have never had any issues with them.
Mike

[edwardb]

Lots of good brands. Just stick with one of the established ones. I used COMP Cam 1.6 Ultra Gold roller rockers in my 306. All good. The engine had Proform rockers in it when I bought it. The geometry was messed up (they were the wrong size) but found out this was a brand to stay away from anyway, so went to COMP Cam's. For street, aluminum rockers are arguably the best.

[riptide motorsport]

May I ask why 1.6? you could bump it up to 1.7 for a little more radical profile on the cam, you should have no clearence issues.

[tirod]

It may - or may not. Depends.

http://www.mustang50magazine.com/techarticles/138_0408_high_lift_rocker_arms/viewall.html

Aside from the mechanical issues of spring crashing or running the tip off the edge of the valve, there's the dynamic issues - does your specific motor actually need extra lift on the intake or exhaust? There's no hard and fast rule. You do what these guys did - run all the possible combinations and find out exactly what's going to happen. Only then do you really know.

Here's the other side of it, too - for the expense of 1.7's, this time, it only worked if they used half of them, and they only got 4hp gain. That's all. Hundreds of dollars spent on parts, hours of dyno time, 4hp.

Keep the focus on what makes the big horsepower, and the little stuff won't slow you down. Good heads, good manifold, good cam, that all work together. That's more important than finessing a low percentage item that costs more than it delivers.

[John Dol]

1.6 because I have a top end kit from Edelbrock and that is the recommended roller rocker.

Thanks,

John

[AJ Roadster NJ]

I'm not a fan of aluminum roller rockers for the street. Those are really a race item, where each rocker will be traded out during routine maintenance and have a fairly short service life. For a long-term street machine, Comp makes an excellent steel roller rocker (here's a link (http://www.summitracing.com/parts/CCA-1442-16/)) that provides excellent performance and low friction.

I've just always thought that the incredibly tiny performance advantage of aluminum (if there actually is one...) simply does not outweigh the risk of a fatigued rocker giving out at some point. Go with steel.

AJ

Incidentally, the link is for 3/8" stud, you may have 7/16".

[CraigS]

No engine expert here at all but judging by the amount of blown up alum. rockers, I'd go w/ some steel ones w/ a roller tip.

[skullandbones]

I have Crane that are made for Ford products. You can see the Ford logo also stamped on it. I trust both names. I think they are 1.7 ratio but that should not be a problem with clearance. Mine are pedistal mounted but if I had bought them new I would have gone with stud mounts. The reason I favor alum roller rockers is the sound you get (reduced mass on valve train). I first heard it with a big block buick engine with roller cam, alum rockers, and alum flywheel. It did't even sound like a hot rod engine maybe a little more like a formula one or some exotic. Well, I like the sound so that's what I have in components. Just check for tightness on a regular basis and do a wear check at the same time on surfaces like the tips. Unless you are a seriously dedicated racer, you shouldn't have a failure. WEK.

[tirod]

If anything, aluminum rockers are actually preferred for the other features they have - the easily controlled positioning of the pivot height, the increased leverage, the larger amount of motion they can perform, the roller tip that reduces scuffing of the valve. The one disadvantage is that they are still individually mounted on their own stud and will bend in all directions. They aren't completely controlled in a to and fro motion, they can and do bend sideways under some loads.

Overall, they can be an improvement over the old rocker ball scuffers, but if the cam lift and rpms are high, then the builders go to rocker shaft kits, not individual rollers. Right now they are a commodity for the interested owner, not necessarily a mandatory item for a performance build. You could pretty much choose by what color you prefer and get a good set - and installing them, clean up some poor relationships and make things work better. That's not about aluminum, that's about attention to detail.

[AJ Roadster NJ]

If anything, aluminum rockers are actually preferred for the other features they have - the easily controlled positioning of the pivot height, the increased leverage, the larger amount of motion they can perform, the roller tip that reduces scuffing of the valve.

I don't think that comparing aluminum rollers to old-school stock steel rockers is a reasonable comparison. If John's original question was whether to use aftermarket aluminum rollers or original stock stamped steel, the answer would be obvious and he wouldn't have needed to ask. His request, as I read it, was to help him sort through the plethora of choices in aftermarket premium rockers.

Many companies (I personally like Comp Cams) make steel roller rockers complete with roller tips and needle bearing fulcrums. The reason they continue to sell a ton of these, even though many aluminum roller rockers are cheaper, is that guys use them for reliable street performance without worrying about aluminum fatigue and failure.

With all due respect, I disagree with almost everything you said about aluminum rockers.

The pivot height adjustment effort is identical between quality aluminum and quality steel rockers.
The leverage is identical between ANY comparable rockers -- 1.6 is 1.6, and 1.7 is 1.7. (Incidentally, I don't endorse 1.7s at all, never have. If more lift is needed, get the correct camshaft and valve springs to achieve it. 1.7s, at least for the street, are almost always an engineering shortcut.)
I agree that there is a difference in range of motion, but steel has the advantage, not aluminum as you stated. Because aluminum rockers need to be slightly larger in every dimension to achieve structural strength equal to a slighly smaller steel rocker, steel almost always has the larger range of motion necessary for high-lift cams. An aluminum rocker will almost always encounter interference before steel. When interference is found with an aluminum rocker during a high-performance engine build process, one solution is usually to switch them out for steel.
A properly engineered roller tip is a roller tip. There is no difference in valve tip scuff from a roller tip on a rocker made of aluminum vs. the roller tip on a rocker made of steel. Again, I think you were comparing high quality aluminum rockers to stock steel, which is not a reasonable comparison.


AJ

Edit to add a link to Comp's premium roller rockers at Summit. Read the blurb at the bottom of this webpage. Good luck John! :cool: http://www.summitracing.com/parts/CCA-1632-16/

[Bob Cowan]

I would agree with AJ.

Alum roller rockers on a street car are mostly a feel good option. I have never yet seen any proof of a performance advantage over non-roller steel rocker arms.

As noted in the article, there's very little advantage to using a bigger ratio than 1.6 on a SBF. Ford did it for the Cobra engine, but I think that was a cost saving measure more than anything else.

- roller tips provide an advantage with valve lifts over about .500"ish. At lifts greater than than, side loading can cause increased wear on the valve guides.
--- But at even a 50% increase in wear means they'll wear out in 50K miles instead of 100K. Only a very few people drive their cars >50K miles.

- roller trunions are bound to decrease friction over the stock sliders. But, it's such a small change that it really doesn't matter.
--- Again, stock parts easily last 100K miles. How much more do you need?

- After market rocker arms are usually higher quality, with more accurate measurements and less variability. You're much more likely to get a 1.6 ratio on 16 aftermarket rocker arms that 16 stock ones.
-- and (IMO) that's a real good reason to get after market parts from a quality company - like Comp Cams.

-- I would muse these rocker arms for a mostly stock or mild engine build: http://www.summitracing.com/parts/CCA-1231-1/

-- And I would use these if the valve lift is approaching the magic 0.500": http://www.summitracing.com/parts/CCA-1231-1/


- Except for the lifters, my entire valve train is Comp Cams. My lifters are stock Ford modified by Keith Kraft.

- I use Comp Cams steel magnum rocker arms, 7/16" stud, 1.6 ratio. Maybe a smidgen more mass, but at <6,500 rpm's, who cares?