aluminum vs stainless adjustable rockers

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lil red

lil red

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so whats the concensus

are aluminum adjustable roller tip rocker arms better than the stainless roller tip arms?

ive heard stories of needle bearings falling out due to failure on aluminum arms, but i've also heard of steel arms siezing/welding to the shafts. One set I looked at had brass bushings which seemed like a good improvement over steel to steel.

Is this more of being application specific?

just wondering what you guru's thought:prayer:
 
well, a very good aluminum rocker arm with out those needle bearings would be from hughes engines...i have a set on my 408 and they worked great while the engine was on the dyno. no street miles yet as the car isnt finished. i also have a set of the same rockers on my 318, but again, no street miles yet, maybe in a month when i can get my car back on the road. lol
sorry, not much help.

http://www.hughesengines.com/Index/...a2VyIEFybXMgJiBBY2Nlc3Nvcmllcw==&partid=24528
 
There's some question over the longevity of aluminium roller rockers for street duty - but I for one have not read of too many well designed alloy rockers snapping or cracking.

That said, the pic below features "alleged" quality rockers (no longer on the market), that clearly DID have a life cycle.

Bustedrocker.jpg
 
PRW makes nice and inexpensive stainless rockers. Broken a few aluminium ones with big valve springs
 
thanks guys

yes hemi - I actually had the stainless PRW rockers in mind - they have cup adjusters - can they be used with stock la pushrods?
 
Ive run the aluminum rocker for a while without any bearing/body failures.

Ive only run them with 375 open psi so far, but Im using some with a mild solid roller '430 open psi' and will let you know if they fail...
 
oh....the bodies would have to crack open in order for the needle bearing to fall out.

The real deal is most people dont routinely check their stuff.
The races in the needle bearing rockers are what wears out 1st, then they ride on the shaft at the edges of the race that hold the bearing in...they make noise just with having the races a lil worn, so to not notice the noise they make when the race edges are scraping and wobbling away at the shafts is ridiculous to me.
 
1wild&crazyguy said:
oh....the bodies would have to crack open in order for the needle bearing to fall out.

The real deal is most people dont routinely check their stuff.
The races in the needle bearing rockers are what wears out 1st, then they ride on the shaft at the edges of the race that hold the bearing in...they make noise just with having the races a lil worn, so to not notice the noise they make when the race edges are scraping and wobbling away at the shafts is ridiculous to me.
Click to expand...
Wild, are you talking like Harland Sharp rockers?? I have those and am getting a little noise on the passenger side, I was just thinking that they might be a little loose, haven't checked it yet, car is on jack stands while redoing the interior, so I have not run it lately, but I guess I should look closer, can you see the problem your describing with out taking the shafts off??
 
Aluminum does not have a fatigue limit, or endurance limit. In other words, the strength will go to "0" over stress and time. This is why Aluminum rods are thrown away after so many runs and why I would never run Aluminum valve spring retainers. Steel and Titanium will degrade then stop at a certain strength. On a drag engine that sees relatively short run time and gets torn down and checked regularly, this should not be a problem for a good Aluminum rocker.
 
For me time seems to move too fast, I rather have something that will last a very long time. I can't believe next month it be 20 years since I first brought my car home !
 
66fs said:
Aluminum does not have a fatigue limit, or endurance limit. In other words, the strength will go to "0" over stress and time. This is why Aluminum rods are thrown away after so many runs and why I would never run Aluminum valve spring retainers. Steel and Titanium will degrade then stop at a certain strength. On a drag engine that sees relatively short run time and gets torn down and checked regularly, this should not be a problem for a good Aluminum rocker.
Click to expand...
For what it is worth one company http://www.bmeltd.com/rods.htm claims there aluminum rods are streetable. Spoke with some one a while back that had a buddy running these rods in his street car with no failure in 10k miles. Seems like a very high $$ gamble to me.......
 
I know I want my engine to last way longer than 10,000 miles.

My rods are 40 year old stock 340's with god knows how many miles. Just has newer rod bolts and been resized....why do I think aluminum would not have last as long?
 
412 Stroker said:
Wild, are you talking like Harland Sharp rockers?? I have those and am getting a little noise on the passenger side, I was just thinking that they might be a little loose, haven't checked it yet, car is on jack stands while redoing the interior, so I have not run it lately, but I guess I should look closer, can you see the problem your describing with out taking the shafts off??
Click to expand...

Pull the rocker, and with a light, look into the side gap and see if the race has been dug into.
The shafts will show shinny lines where the races rub.

tight side play of .010 will extend the life of the needle bearing race, thats the only part that 'wears' out. Rocker specialties will replace bearings for $120 or change to bronze bushings, same price.

I dont buy harland sharps, I buy the cheaper 'same bearing/spec requirements' $130 rockers, then if I have to fork 120 for a rebuild...im still under 600+ that the brand name gets.
 
Aluminum seems to flow faster than stainless (neither are very strong) Case in point, the Aluminum power cables they used to wire up buildings with had a tendency to lose the torque on their compression fittings, the metal would "ooze" out over time. You could crank down a lug to 25 ft/lbs and in a month you could get another 1/8 turn out of it. month after month. Imagine a race car with solid lifters and 700 lb springs parked for a month with 1/4 of the valves held open. Do you think that AL rocker will give a little? I know they are forged and not recommended for mega springs, but the cast iron ones are bullet proof. Stainless ones are nice looking but are not that strong either, ever see a stainless head bolt that gets 85 ft/lbs torque? With all that said...I actually have a set of MP aluminum rockers waiting to go on my motor but my springs are only slightly over stock, and I was going to buy the stainless ones too but the vendors price almost doubled since I last looked at them. I heard BME rods were streetable too, something about the shock absorption factor that made them last...I got a used set for a RB but never ran them becasue my motor was already balanced. I polished them up (looked fantastic) and gave them to my gearhead friend for tap handles at his custom bar.
 
I run the Comp Cams Pro Magnum steel rockers on my car with 591 lift cam and open spring pressure around 350 if my memory serves me right. These rockers are not bushed but I am not running enough open pressure to cause any problems. They have to be shimmed right and don't over torque the hold downs or failures can happen. Also people tend to put the shafts on backwards so oil hole is not in the right place and that will cause problems. If you run non bushed steel rockers with over 400 pounds open pressure that won't work too well.

Nice thing about the Comp steel rockers is they are low profile allowing stock valve covers to be run without hitting them.
 
im also running the comp stainless rockers on my 416 with a lift of 585 so far no problems on the dyno cars not finished yet do to leg amputation
 
Harland sharp and all the pro comp/off brand e bay 'aluminum rocker arms' fit under stock valve covers.fwiw

There is some work needed in the making of spacers and hold down widths in order to obtain perfect roller to valve tip alignment, and of corse... 'correct side play'
Most don't do the work and so they basically set themselves up for catastrophic failure.

Someone else said this too, and they're right....
These are racing parts, like on a race car...you need to periodically check them and know you're noises to diagnose.

As for the comps.. I like the $589 ones with the bushing, just wish they had a 1.6 in that version.
 
The rockers I pictured were a Bronze bushed item. The way they snapped, there appeared to be a "thinness" in the manufacture around the spring relief.

That said - they ran on full season on an 11 sec flat tappet car , but I got them and ran them on the street, and both broke in almost identical places over a 6 month period.

No funny noises - just "crack" . Shafts were perfect.
 
"Aluminum seems to flow faster than stainless (neither are very strong) Case in point, the Aluminum power cables they used to wire up buildings with had a tendency to lose the torque on their compression fittings, the metal would "ooze" out over time. You could crank down a lug to 25 ft/lbs and in a month you could get another 1/8 turn out of it. month after month."

I apologize for hacking this thread but the above statement is not exactly true. The metal doesn't "ooze" out. Current flowing thru the conductor creates heat, AL expands and contracts much more than CU during these heat cycles, which in turn loosens the connection creating more heat from a bad connection and the cycle will perpetuate until failure (usually fire). That is why some connectors are rated AL or AL/CU and some are not. AL is still used widely for service feeders, just not for branch circuits

Again, sorry for hacking the thread, carry on
 
Comp stainless with bronze bushings. The bronze bushings have more contact area than needle bearings so more support. No needles to get scattered around and cause a greater failure. I had them in a 360 13 years ago and they are in that same small block in its 3rd incarnation right now. No failures.
 
I have a set of Indy roller rockers on my 340. It's got a hydraulic flat tappet with .510 lift. The rockers are the 1.6 ratio. It's been together for 4 years now, about 4000 miles with no problems so far. Just my 2 cents.
 
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