Bonneville America Forums Forums Technical Forums Performance Mods Advanced exhaust cam

Well, finally got around to advancing my exhaust cam a tooth. Wasn't really blown away with difference. Lost quite a bit on top end, didn't realize the massive torque gains I've heard about at low end. Posted over at Delphi, there was a long thread about it. Seems to only work on the 790cc 360 degree engines, not the 270 degree. Guess I'll be changing it back. Glad I didn't bend any valves.

Bending valve's should not be a concern as your actually opening the exhaust valve sooner rather than later when advancing the exhaust cam. Also, you are correct about this mod being for the 360* motors. The 270* motors typically make more torque than the 360's due to the existing cam timing..( lack of overlap )

How about for the 865 engines? Has anyone tried this?

The 865 have much less valve overlap than the 790 motors. In fact, it's only something like only 9 degrees of overlap(or was it underlap?) while the 790 motors have 24. That's why the torque specs are better for the 865, while there's more horsepower on the top end for the 790s.

Did anyone ever determine if the 865 motors could retard the exhaust cam for benefit?