DucaT

As I have read, the stock cam is rifle bored, and is hollow.
A lot fo motorcycles have gone to hollow camshafts in order to lose weight and make for a lighter valvetrain in OHC applications.
From the things I have read about the LS1, it was done to lower NVH.
So....

All you guys who are running aftermarket cams, are they hollow as well?

Or are they lopey enough so that the NVH aspect of a more aggressive cam is cancelled out?

The One

:confused:

I thought it was the valves (then only on an 02 Z06) that were hollow?

JC

99 Corvette

The stock cams are hollow (don't remember why) and the Z06 valves are sodium filled (not hollow) :cheers:

Jerry

C5Noir

Yup and don't cut those valves open, Na and K with lots of O2 = BANG!

The One

Sort of... ;) This is from an article on the Z06 cam:

"With the higher lift, we needed to reduce the mass of the valvetrain or start getting into a float condition," John Juriga commented. "We went to hollow stem intake and exhaust valves, very similar to what we used in the ’96 LT4. We pushed the edge with a state-of-the-art, 0.8-mm. (valve stem) wall thickness–very thin stuff. The exhaust stems are sodium-potassium filled."

They would have to be hollow to fill them with something, eh? :D

vanroth

Not O2 but H20!!!

vanroth

Walt Donovan

My guess for the hollow cam is that it's hollow because it can be. GM finally started making cams with bigger journals (the LS1 is 55mm). This allows a lot of advantages. Base cirle is bigger. That means lower presure angles and quicker accelerations without negative radius flanks. The cam is stiffer so natural frequencies are raised a bunch. Whole valvetrain is more controllable. Which brings me to the hollow core. There's so much camshaft now, they don't need the middle any more.

AP

Wow ! Wouldnt that make them pretty fragile...

pkmoose

great reply Walt, thanks :cheers:

nevrenuf

I've installed numerous aftermarket cams in LS1's and LS6's... from Lunati, Comp Cams, and Crane.. all were rifle bored..

AP

C:cool::cool:L

DucaT

Great, Thanks neverenuf
That was exactly the answer I was looking for.

I am not really sure if I understand why they are hollow beyond the weight advantage. Yeah, OK, the cam is larger and so now it is strong enough so that it can be hollow.

Like I originally posted, I can't figure what the hollow part has to do with the Noise/Vibration/Harshness aspect.
Whatever the advantage is, I'm glad that the aftermarket cams have included that in their construction.

Thanks fellas...........

nevrenuf

I'm told that the hollow bore is a stress relieving process and that it allows the heat treatment to be more effective..