Just bought a set of bbm pro comp rockers. They have bushings in them. Does anyone know what these bushings are made of, why bushings. Why not the aluminum body.

They are sleeved....with coated copper I believe. They work great! Haven't had any issues with them or the valve covers off all season so far. I did size a lot of the spacers to fit though during the build process. I have a lathe so it was no big deal.

Why not just run the aluminum body directly on the steel shaft?

1. Anywhere whatsoever basically totals the rocker, unless you have the facilities to board the hole oversized (without altering its location), and then put a bushing in. for something made with a replaceable bushing, you press the old one out, press the new one in, ream or hone to size. Your component is now far more easily kept serviceable, with just an arbor press and a drill press.

2. Aluminum is not a really great bearing material against Steel. If there is ever a problem with it running dry, it's fairly prone to galling. Brass and bronze have much better inherent lubricity, and are more forgiving of occasional insufficient lube.

Because they are not aluminum...

Good one captain obvious

Gus

Check the rollers over the valve tips for wear.
Not pro-comp, but CAT rocker I had the rollers really starting wearing.
Really my cheap CAT stainless rockers, the rocker bodies are nicely made with good geometry, but everything else like was sub-par.
I still have them, and though of rebuilding them with quality adjusters and roller tips, but that is more cost than I paid for the entire setup.