Weight of Small Block Chevy Valvetrain Components

[Chris Hill]

Hello,

With the current discussions of what causes small block Chevy rockerarms to fail, I would like to perform some basic calculations but I don't have the data in front of me.

Could someone share the weight of each component in a stock eliminator small block Chevy valvetrain, specifically:

1. Lifter
2. Pushrod
3. Rocker arm (do not include lock-nut, washer, or pivot ball)
4. Intake valve
5. Exhaust valve
6. Valvespring
7. Retainer
8. Keepers

Thank you,

[Jeff Lee]

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!

[Chris Hill]

Anything will work, just need something to do some rough calculations. Going to calculate how much of a safety factor exists for the stamped steel rocker arms.

[Chris Hill]

These are weights from a Big Block Chrysler with the infamous Isky ductile iron rockerams. They are much easier to find around the shop than Chevy stuff.

1. Lifter 111 grams
2. Pushrod 73 grams
3. Rockerarm 184 grams
4. Valvespring w/ retainer and damper 144 grams
5. Intake valve, 2.08" I think (didn't measure), 136 grams
6. Keepers 10 grams

[Bill Edgeworth]

This is not a simple task. You will also have to figure out the mass/inertia properties of the rocker arm. This will vary widely with design and ratio.
You will also have to know the approximate cylinder pressure at the time of valve opening to figure out the additional pressure required to overcome the force exerted on the face of the valve by the combustion gases. Some of the higher end CAD systems are capable of doing most of the work but you will still have to draw a solid model of the rocker arm

[Chris Hill]

Bill, you are 100% correct. However, for a pushrod type valvetrain, the general rule of thumb is 1/3 of rocker arm mass should be applied to valvetrain effective mass measured at the valve.

The combustion pressure can be ignored as once the valve is cracked, the pressures psudo equalize on both sides of the valve and the net force is realtively low compared to inertia force and valvespring force. You have to watch valve spring load on the seat with boosted applications. The boost wants to push the valve off the seat.

I'm estimating the safety factor for the rocker arm. If I'm off a little bit, does not matter much, as the safety factor will come in around 3~4:1. If the safety factor is 1:1, then things are more critical.