The Spinning Top Test

Imagine spinning a top on a table. If it is perfect, it spins smoothly in one spot—it almost looks like it is standing still. Now, imagine that top is slightly bent. It wobbles. It wanders around the table. It vibrates.

Your engine valves are just like that spinning top. They spin thousands of times every minute. If they "wobble" even a tiny hair's width, they won't seal the engine.

In the engine building world, we have a fancy word for "perfectly centered." We call it Concentricity.

What is Concentricity?

Concentricity simply means two circles share the exact same center point.

1. Circle A is the Valve Stem (the stick part).
2. Circle B is the Valve Face (the part you grind).

If the Face is perfectly centered on the Stem, the valve is concentric. If the Face is slightly off-center, we say it has "Runout." Runout is bad. Runout means leaks.

The Hidden Trap: Valve Stem Wear

Here is the problem that trips up most beginners (and even some pros). When you take an old valve out of an engine, the stem isn't perfect anymore. It has been sliding up and down millions of times. It isn't a perfect circle anymore; it might be slightly oval-shaped, or narrower in the middle than at the ends.

This is where your tools make or break the job.

If you put a worn valve into a cheap, standard clamp (called a "collet"), the clamp squeezes tight against the outside of the stem. If the stem is oval, the clamp holds it crooked.

• Result: You grind the valve face based on that crooked hold. You might make the face shiny, but it is now off-center. When you put it back in the engine, it won't seal.

The Solution: The 6-Ball Principle

To fix a valve right, you can't just squeeze it. You need to find the true center of the valve, ignoring the wear and tear on the surface.

This is why the Kwik-Way 6-Ball Chuck (used on the SVSII Deluxe) is famous in the industry. It works differently than a standard clamp.

Instead of three flat jaws squeezing the valve, it uses six hardened steel balls.

• There are two rows of balls.
• These balls act like a tripod. They touch the valve stem at specific points and "float" to find the exact center of the valve, even if the stem has some wear or taper.

Why "Centerline" Grinding Wins

We call this Centerline Grinding.

Think of it like this: A standard machine grinds the valve based on the outside (which might be worn). The 6-Ball chuck grinds the valve based on the invisible center line (which is always true).

When you use a 6-ball chuck:

1. Zero Runout: The wobble is gone.
2. Better Seal: The valve lands perfectly in the seat every time.
3. Longer Life: Because it doesn't wobble, it doesn't wear out the valve guides.

The Final Check

How do you know if you did it right? You use a runout gauge. You place the valve in a tester and spin it while a dial measures the movement. If you used a standard collet on an old valve, you might see the needle jump. If you used the 6-Ball Centerline system, that needle should stay dead still.

That stillness is the sign of a perfect valve job.