[pastry_chef]

Originally Posted by gtofreek

most stud mount aluminum rockers are iffy when using spring pressures over 350 lbs. Especially cast aluminum rockers. They are only good for bone stock applications as far as I'm concerned.

Harland Sharp's will handle anything until you NEED T&D or Jesel shafts.

http://www.rehermorrison.com/superSeries/540Start.htm

http://www.shafiroff.com/pro/565_1000.asp

http://www.harlandsharp.com/

Ask Jim Hand or countless others how their Harland's have served them.

[Geoff]

Murf,
I think the 17-4, 15-5, is the percentage of Chromium & Nickel, respectively, in the steel alloy. Probably find one is better in one area than the othert, but both are well inside their safe operating limits of strength.

Steve C [ post #11], Crane would say that wouldn't they!!
The type or method of manufacture of aluminium makes no difference. It is a fundamental propery of alum that it will fail from repeated stress cycles, but there is no known method of measuring or predicting how many cycles are needed before failure occurs.

[Rugratman]

I was not aware that Crower made 1.65's ?

Only 1.5's and 1.6's.
Do they now?

[Steve C.]

Stated- "Steve C [ post #11], Crane would say that wouldn't they!!"

Yea, just a bunch of liers like all the rest of them Including Lunati who states their aluminum roller rocker arms are proven to endure more than 100,000 miles !


fwiw, I'm not pushing for aluminium and I'm aware that it can have a tendency to fatigue. And the last set of heads I had assembled that did not use a T&D shaft system used Crower stainless steel rollerized rockers. Point is, depending on the application don't discount their use all together.

[PONTIAC DUDE]

I have run HS for over 20 years. I ran HS on the wides car for over 25,000 miles after taking them off my 2 yr old roller combo. Still on her car. My current CV-1 uses HS as did the same engine with E-heads before it. Use them with 400 plus open (beehive springs)and 6600/6800 rpms constantly. Never had ONE issue.

My deal. If it taint broke don't fix it.

BTW: they started the roller rocker industry.

[Steve C.]

If you look at the featured engines within the Torque Power section of Bill Boyles Pontiac Street Performance web site about 40 percent of them use Harland Sharp rocker arms.

[Skip Fix]

Correct me if I'm wrong but aren't most shaft rockers aluminum?

[440GP69]

yes most shaft rockers are alum, jessel, td, crower, yella no terra, tomahawks, all are strong as hell and are designed for max effort springs, i still like the crower ss shaft rockers but unless you are running monster springs and huge roller cams you don't need em, FWIW if you want a shaft rocker that fits under a stock valve cover the tomahawks may be the deal as they are the only off the shelf D-port shaft rocker i know of and at 795 a set they are priced well compared to a top of the line stud mount setup.

[NO67GTO]

I have JBP alu 1.5 roller rockers on my street strip 455 w/ 96 heads for 5 years and have seen no sign of fatgue or stress. Pivots still roll free and smooth. I just have a hyd cam no roller or crazy spring pressures. Good luck.

[Old Man Taylor]

Originally Posted by Rugratman

I was not aware that Crower made 1.65's ?

Only 1.5's and 1.6's.
Do they now?

I have Crower 1.65's on my GTO. They started as small block Ford parts and they changed the trunion to match a Pontiac. I've had them on since somewhere in the mid-80's.

[440GP69]

yes crower has 1.65's ace at ppr carries them but normally most vendors only show 1.5 and 1.6 for some reason

[Rugratman]

Yep, they sure do have them.....Gonna order them today.
Thanks.

[tobstealth]

Geoff,
Just info.
17-4pH Stainless is made by precipitation-hardening stainless steel. Offers a good balance between corrosion resistance and strength. Magnetic. Hardenable to various strength levels and hardness by varying the aging heat treat temperature. Typically provides better corrosion resistance than the 400 series stainless steels, and better strength than the 300 series stainless steels. Often used for aircraft, dental, marine, medical, surgical, and applications where high levels of strength and hardness, and good corrosion resistance is required.

15-5 stainless is a 15.0% chromium stainless steel that provides the corrosion resistance of 440 C with the added benefit of improved carbide size and distribution for noiseless miniature precision bearing operation. The alloy can be through-hardened to achieve a minimum hardness of Rockwell C 60. The optimized alloy additions of C, N, Cr, and Mo provide a combination of the best carbide structure, corrosion resistance and heat treat response. The high hardness and corrosion resistance make it a suitable candidate for use in miniature bearing, cutlery, medical implement, and other special applications.
Tensile properties are for Austenitized at 1975°F, warm oil quenched, subzero treated to -120°F, and tempered at 350°F

Both are well suited for the applicaiton.

Aluminum displays very different properties depending upon how it is processed. Billet or forged aluminum is not processed quite the same as steel but is still considerably stronger than cast aluminum. Casting does not provide as dense a material and does not align the grain structure of the material - when it fails, it has a rough gritty looking surface where it failed. Forged or billet aluminum will srtetch as it fails and has a smoother torn look. A well made aluminum rocker is adequate for 90% of the applications out there. It will take repeated stress cycles almost indefinitely as long as the load is equal to or below 70% of it's yeild.

Sure some say that aluminum is not a suitable material for rockers but they also used to say that it was not suitable for connecting rods, blocks, etc.

If you have an aversion to Al that is fine, stick with what you are comfortable with by all means. Just wanted to let you know that all the Al rocker manufacturers out there are not selling junk.

[Old Man Taylor]

Originally Posted by Rugratman

Yep, they sure do have them.....Gonna order them today.
Thanks.

The only thing to watch out for if they are the ones originally designed for the SBF is that the pushrod ball heighth is higher. That means you will need a slightly longer pushrod for the correct geometry.

[Geoff]

tobstealth,
Quite agree with your statement that the ".... alum rocker is adequate for 90% of the applications out there". What we all want to know is: will the 10% that fail be in my engine when they fail!
For a few bucks more, & peace of mind, I'd rather use steel or s/steel & be covered 100%.

Alum conrods? Know plenty of people with 100,000+ miles on steel rods, don't know of any with alum rods.

[Rugratman]

Originally Posted by Old Man Taylor

The only thing to watch out for if they are the ones originally designed for the SBF is that the pushrod ball heighth is higher. That means you will need a slightly longer pushrod for the correct geometry.

Son of a b*tch....alway's something.
Thanks for the heads up.

[tobstealth]

You can get 100K miles if you treat them right. I personally have not gone past 70K - had BME and sold the engine. The only real tricks are 1-set clearances for the rod of choice and 2-don't thump it until after the engine has gotten to operating temperature.
They last alot better than I had expected.