Quote:
Originally Posted by Chris Hill
Sorry I've taken a long time to reply, but here's what the engineering calc say:
1. If you take all the worst case conditions for a valvetrain force WITHOUT IMPACT occuring and current Stock Eliminator valve spring forces, the peak load is approximatly 1,000 lbs at the valve.
2. Per a test by David Vizard in his book, Small block Chevy Valvetrains, a stock Small block Chevy rocker arm breaks at 3,000 lbs.
3. The safety factor on the rocker is 3:1. In lay terms, the the rocker arm is 3 times as strong as it needs to be and will last a VERY long time if impact does not occur.
You can try to beat around the bush all you want, but a rocker with that much safety factor will not fail if the camshaft is designed correctly for engine speed.
Why am I very confident in my statements? Because I have run or supervised valvetrain performance testing and durability testing for 1000+ hours of spintron time.
A higher quality rocker will help the situation some, but it's like putting a band aid on something that needs stitches.
Better materials and heat treatment DO NOT replace correct design and engineering of the camshaft events.
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Well Chris a blind man could see you were going to end up with these conclusions! And that's why I made the first post
And not trying to get personal, but it's obvious you have failed to understand the parts offered today are inferior to yesterday. Done, end of subject.
When you asked for all the weights of the SBC valve-train, I immediately asked a few questions because as I stated, The devil's in the details". To refresh:
How does the "modern" cold stamping process, inferior metalurgy, and subsequent poor quality product figure into your calculations?
Which rocker? OEM non-rail, OEM rail type, PVS (Precesion valve systems), Crane Nitro?
What size valvespring are you looking for? 1.250"? Larger is possible and still comply with the rules. Behive should be considerably different in weight.
What size retainer are you looking for? Behive should be considerably different in weight.
Stock steel retainers (what valve spring size?) or chromoly or maybe the new machined tool steel (lighter than chromeoly, almost as light as titanium)?
Solid lifter, hydraulic or hydraulic roller? What lifter, standard replacement, Schubeck with puck or Schubeck with all composite body? Tool steel lifter body?
What pushrod? 5/16" 3/8" 7/16", maybe 1/2" per the new rules? Chromoly or standard?
I haven't seen the new rule so maybe by now composite pushrods are legal (just like composite body Schubecks are legal).
What valves? Hollow stem or standard? Hollow stem of course would not be legal. At least Inot that I'm aware of.
The devils in the details!
I note you did not address these concerns. If your discussing the science of the issue, I would think it would be imperative these issues are addressed.
On your last post you stated:
A higher quality rocker will help the situation some, but it's like putting a band aid on something that needs stitches.
Great observation. A higher quality rocker will help the situation. Absolutely. But is it a band-aide when you substitute a "yester year" SBC stamped rocker for "today's" inferior product? If "yester Year" parts are long gone, then what? A suitable substitute is needed.
And I'm sure with over a 1000 hours on your spin-tron you recorded the rockwell hardness of all the stamped rocker arms you used. Right? What other methods were used to insure the quality of the parts you tested? What percentage of time is a spin-tron in use with stamped rocker arms and no aftermarket support systems (stud girdle)?
Chris, I admire you for taking the initiative and if proper testing was noted I might be swayed. But your own evidence seems to support the fact that higher quality rockers are needed. The issue is where do we get the higher quality rockers?
I might be even more swayed if your family took the non-OEM rockers made of ductile iron instead of stamped steel of the 440-6 'Cuda and replaced them with what the factory placed on the engine as it rolled down the assmbly line. I think then you might be crying a different tune. Or is this a method of protecting an unfair advantage???
